UberEats could be underpaying delivery drivers on 21% of trips - <AUTHOR> https://www.businessinsider.com/uber-eats-driver-who-scraped-data-alleges-wage-theft-report-2020-8 <comment><USER3> Uber is making it harder and harder to get on board with the idea that it's not an employer. Leveling out people's pay over multiple trips or retroactively adjusting the reward per job sure sounds like an employer having very strong control over the work conditions and compensation. And this almost brings back echoes of Doordash (?) when it was caught taking drivers' tips so that their pay was reduced to the minimum hourly promised "wage".

It's like Uber are trying to shoot themselves in the foot with all the cost squeezing and profit seeking at the same time they're in a fundamental legal fight defining what they are.

You would think they would go in the opposite direction and pay people such good rates during this controversy, you could hold that up and say, "see? People are clearly much better under this system". But I guess not.

On a separate note, I will say that this is pretty expected in terms of how software errors go. Of course programmers at a company will be checking quite diligently that they're not _over_ paying through their algorithms. But underpaying? Only those who can't easily check your code are harmed by that one. It is a rare company that spends money and resources on verifying from their users' point of view that they're being delivered what was promised -- unless that company actively cares about the user.

<comment><USER4> > It's like Uber are trying to shoot themselves in the foot with all the cost > squeezing and profit seeking at the same time they're in a fundamental fight > defining what they are.

I don't think they have a choice. UberEats is fundamentally unprofitable. If it was run profitably, the high(er) prices would drive a large portion of their customers away and into the arms of other "startups" willing to run at a loss or towards picking up the food themselves. Plus Uber can't pretend to be an early-stage startup anymore and their constant quarterly losses are starting to add up.

I'm still not convinced this new food delivery industry is viable without constant cash injections.

<comment><USER5> I wouldn't go so far as saying they're "fundamentally unprofitable". They have a couple long-term options: the often-discussed one is autonomous driving (though it's becoming increasingly obvious this is many years out), but the less discussed one is vertical integration.

It's not hard to imagine them choosing to pursue Amazon-style vertical integration where they own the "restaurants" themselves. I put "restaurants" in quotes, because it'll almost certainly just be warehouse-style kitchens, where drivers skid up out front and grab food from heated tables, and you won't be able to dine-in at all. It would fill the same role for aspiring restaurateurs as food trucks do today: a startup cost, low-barrier to entry way to build out a brand, rapidly iterate menu-items, and begin building revenue to eventually secure a business loan to open a proper restaurant.

If UberEats can really squeeze both the drivers AND the restaurants, there's no fundamental reason that food delivery can't be done profitably - <USER2> companies have been doing it in almost all markets for decades.

Brick and mortar retail stores got eaten by Amazon warehouses, and it seems inevitable that many brick and mortar restaurants will eventually get eaten by a massive tech company as well.

<comment><USER6> > _It 's not hard to imagine them choosing to pursue Amazon-style vertical > integration where they own the "restaurants" themselves._

I always wondered something about those meals that are available on airplanes:

in the past I liked quite a lot most of them (e.g. a small piece of meat/fish/other, some vegetables and/or rice, a slice of bread, a small dessert) => wouldn't it be quite profitable to have a similar delivery service for "kits/menus" like those ones (just e.g. ~4 different "kits" available to be ordered daily), cold (but pre-cooked if needed) that only need to be warmed up at home? (if 3 stewards/esses, on a moving tube, managed to warm that up for 300 people then I guess that I'll manage to do the same for myself at home)?

I admit that on one hand the "delivery"-part of the service would be related only to getting fresh (uncooked or "freshly pre-cooked") stuff (not ready for consumption), but on the other hand that way the delivery could be spread over a longer timespan (multiple deliveries per trip, better delivery organization, therefore less costs) and could be left in the mailbox (assuming at least a mediocre insulation of the package).

Here in Switzerland/Zurich I am aware of some similar services, but they deliver only the ingredients (then I would still have to actively cook). Supermarkets do have some similar pre-cooked stuff, but most (not all, but most) is quite terrible (probably because there the stuff has to be able to lie there for days/weeks - definitely not similar to what I used to eat on airplanes) and especially it never changes.

(I used to fly only in Europe using "Swiss", "Air Berlin", "Lufthansa", maybe as well "KLM"/"Air France", always to/from Zurich - your experience with other airlines / in other location might be different)

Woudln't it be nice to get back home and find in the mailbox a ready-to-be- warmed-up (maybe actually "cooked", but in an extremely simple way) menu?

The delivery, being all sourced from the same place and being spread over many hours would not be as expensive as it is currently done for hot stuff coming from multiple restaurants, and the small amount of different menus (4 as mentioned above or slightly more) would allow to buy more source material for less $.

EDIT: I admit of not having any clue how the companies that prepare meals/menus for airlines operate => there might therefore be some important details that make the whole concept crumble... :)

<comment><USER5> Switzerland is strange because restaurant food is so tremendously expensive there compared to the rest of the world. In most cities in America, for $5 you can get a half-decent meal that's quite a bit more palatable than airline food, and for $10 you can get something from (mostly immigrant-run) restaurants that's somewhat nutritious as well.

There are meal-delivery services here that are basically what you describe, but they usually deliver food weekly and they're kind of pricey. They're mainly targeting time-strapped single people who are trying to eat healthier and don't want to do all the mental work that goes into grocery shopping, meal prepping, cooking, etc.

<comment><USER6> Thanks for the reply - I agree & disagree with you.

On one hand you are absolutely correct stating that swiss restaurants are in general more expensive than anywhere (subjective - e.g. a 30$ small menu might be ok here, but we do have as well a higher income and going to the restaurant is not something that people do often), but on the other hand I did like airline food (which you basically describe as being "the worst" while for me was on par with one offered by restaurants), therefore we have a mismatch of our experiences.

(talking about restaurants, I must mention that Stockholm was for me a lot more expensive than Zurich)

Personally, I would have all kind of doubts about a $5 meal (in most parts of the world, if it's not something extremely simple).

> _There are meal-delivery services here that are basically what you describe, > but they usually deliver food weekly and they 're kind of pricey. They're > mainly targeting time-strapped single people who are trying to eat healthier > and don't want to do all the mental work that goes into grocery shopping, > meal prepping, cooking, etc. _

I'm not currently aware of something like that in my area , but my profile is very similar (and I did try to cook different stuff, but the failure rate is quite high and the overall quality quite low). Still, I think that the concept that I described was a bit different than that?

<comment><USER5> I can expand upon the $5 - $10 meal by example.

I'm from southern California. I worked in Wellington, New Zealand for a stint, and I found that restaurants were priced about the same as back home. That is to say, an average sit-down restaurant meal of equivalent quality was roughly the same price in USD.

However, in America, there's an entirely different class of _much_ cheaper food (takeout food), and younger people in metropolitan areas eat this food very often. These were usually powered by cheap immigrant labor, often paid under the table to skirt taxes and mandatory benefits.

Labor protections in New Zealand are much higher, of course, and without an easily exploitable underclass, this food simply can't exist there. There weren't really regular kiwis who ate out 1 - 2x per day - virtually all of them cooked most of their meals at home themselves.

This is the environment in which these food delivery companies are operating. These restaurants already have extremely thin margins, consumers are price- sensitive, and as long as the delivery company is just a middle-man, they'll struggle to do this thing profitably. If they lose access to their cheap labor by having to re-classify drivers as actual employees, it might be impossible.

<comment><USER6> Interesting! Thank you :)

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER7> What matters is the aggregate amount over multiple trips. If you underpay on some trips and overpay on others and it is a net wash, then it doesn't really matter for the couriers if the payment algorithm is on the low side on some trips so long as it is on the high side on other trips.

Under or overpaying on trips is more of an interest to those engineers trying to optimize marketplace efficiency. Meal delivery businesses have as much of an interest in not underpaying as doing so reduces supply availability and therefore reliability and they have also an interest in not overpaying as that reduces profitability. The ultimate goal is optimal pricing in a three sided market to maximize liquidity as the business model does best when you optimize for volume of transactions. Maximizing liquidity amortizes fixed costs over more transactions. This applies as much to the meal delivery companies as to the restaurants involved.

At the end of the day, distance driven is very imperfect as you have issues like poor GPS signal and in cities you have the dilemma of urban canyons and tunnels. Also, drivers don't always take the suggested route. At vehicle speeds, it's hard problem to solve due to time between GPS pings. Another issue besides GPS inaccuracy is clock inaccuracy, especially with round-trip times between server and client and client and server aren't always symmetrical, especially on cellular networks, and this messes up all sorts of clock synchronization strategies. The peanut gallery on HN is seriously underestimating the complexity of measuring distance using GPS. It's pretty darn good when conditions are ideal, but when they aren't, good luck.

Another question is the magnitude of the underpayment in the 21% of trips. Are we talking about 1-2%, 5-10%, some other deviation? If it was something like 1-2%, we should all be amazed. Gage repeatability and reproducibility matters.

<comment><USER8> Yeah, and also if Uber was doing this intentionally, they could've just as well lowered their $/mile rate if that's what maximizes profit.

<comment><USER9> Lowering the "front page" $/mile rate could make the service immediately less attractive to workers, who can select between multiple services based on the apps on their phone. Lowering mileage paid is much harder for workers to detect, since it requires carefully checking each trip and measuring what's actually paid.

This could also be an "unintentional-intentional" bug, meaning its presence was just an accident -- but that the company has chosen to prioritize its engineering resources addressing issues that improve its revenue, rather than decreasing it.

<comment><USER7> In a business that is trying to optimize a marketplace, accurate measurability of everything matters as the performance of every marketplace optimization is degraded by having poor gage repeatability and reproducibility in its measurements. It's like trying to play darts when you're nearsighted and have 20/400 vision. This is process engineering 101 stuff.

There's way more money to be made in having accurate measurements than having inaccurate measurements that optimization engineers can't rely on. The more accurate the measurements, the more confidence you have that your marketplace optimization algorithms are producing the desired marketplace dynamics.

</comment></comment></comment></comment><comment><USER10> On a related note, I don't understand the point of tips on UberEats.

(a) I thought the whole point of these apps was to simplify things for the user. I just want to know how much I pay in total, upfront, as I'm selecting food. Include taxes and delivery fees in a big fat "this is what you will pay" display on the screen and I'll be a 10X happier user. Delivery apps were a great opportunity to axe the complexities of tipping culture and they screwed it up IMO.

(b) They ask you for tips _before_ they even dispatch your food, which makes zero sense to me. Tips are supposed to be "extra" based on the quality of service, so how are you supposed to blindly give 10% or 15% without even having received service? (I always put 0% when ordering and up it to 10-15% on delivery OR give cash tips, which is how things have always worked before the age of apps, but it's cumbersome to do that.)

<comment><AUTHOR> (b) you can change your tip afterward if your service was not as expected.

Just like in a restaurant: maybe your default tip is 25%, but great service bumps that up, and bad service bumps it down. You go in expecting to pay 25%.

<comment><USER11> We bought a second car at the weekend, I phoned up my insurance company and asked them to put it on. They did so, and it was cheaper than the quote I'd got online - £180 for 9 months vs £290 for 12 months.

So I immediately tipped the person on the phone £45

How ridiculous does that seem?

<comment><USER12> I've even started asking my friends and family for tips anytime I do anything for them.

US culture of tipping is so ridiculous that I think people actually derive enjoyment from tipping by giving themselves an ego boost when they do, as some sort of charity or having role played as an extremely rich person being benevolent with their wealth.

<comment><USER11> That's the point. There's a friend episode where Rachel and Ross go out for dinner with her Dad. He pays the bill ($200 or so - fancy resturant) and goes to the bathroom. Ross comments he'd 'only' tipped 4%, and leaves some cash.

Great putdown when the father comes back, sees the tip, rips up the credit card receipt and tells Ross to pay the whole bill if he wants to be the 'big man'

</comment></comment></comment></comment></comment><comment><USER13> The salon source linked in the article has a bit more (and slightly different?) detailed information, including a link to the tool developed to track mileage

[https://www.salon.com/2020/08/20/programmers-say-uber- eats-i...](https://www.salon.com/2020/08/20/programmers-say-uber-eats-is- systematically-underpaying-their-workers/)

[https://chrome.google.com/webstore/detail/ubercheats/pkdblhe...](https://chrome.google.com/webstore/detail/ubercheats/pkdblheaeakedkbkfhoeepgmfiajjdgn)

<comment><USER13> also, the extension author is on twitter if you have questions

[https://nitter.net/ArminSamii/status/1295857106080456706](https://nitter.net/ArminSamii/status/1295857106080456706)

</comment></comment><comment><USER14> Hard to know what to make of this without seeing the full data. On 21% of trips, Uber undercounts the miles. What about the other 79%? Spot on, or is there over counting?

<comment><AUTHOR> Most spot on (within 0.5 mi), some overpayments.

Overpayments are much less frequent than underpayments, and regardless: when someone accepts a trip, who knows if they did it because they thought "that amount sounds fair" or thought "that amount given the distance shown sounds fair." The only fair thing for Uber to do here is to rectify all underpayments, and let the overpayments stand.

Further: just because Uber couldn't find a route as efficiently as the extension could doesn't mean it was an overpayment. The extension uses Google Maps. If the driver used Uber Navigation to navigate, and Uber navigation was twice as long as Google's - is that really an overpayment?

<comment><USER15> Can you share one route uber underpaid by big margin?

For the second part I agree, but without seeing outlier, maybe in some cases google couldn't find the best route, compared to the app.

PS: all this stats used Google Maps shortest path or best path?

<comment><AUTHOR> [https://imgur.com/v4bSD5S](https://imgur.com/v4bSD5S)

I was paid 1 mile, actual distance 3.5-4.0 miles.

Previous versions of the app would use the first result returned by Google Directions API, which could have been best not shortest (I'm not sure, anyone know?). Newer version (pending app store review) does shortest always.

<comment><USER16> The problem is you used Uber Car, instead of Uber Airplane (please don't)

<comment><AUTHOR> I just got a lease on an UberCopter. Runways are too far from restaurants. Hope it works out for me!

</comment></comment></comment></comment></comment></comment><comment><USER17> Always deplatform your tips.

<comment><USER18> Agreed, but keep in mind that the platforms have started making design changes to discourage this. Some of them now surface the tip to the driver which can lead to $0 in-app tips lowering the displayed value of your request so you end up being passed over for other people. If you don't tip in the app you risk waiting a lot longer for service.

</comment></comment><comment><USER19> Why would there be a buy in the Eats tracking but not in Rideshare? I'd imagine it's the same underlying GPS tracking/routing software used in both cases. Is it just that the rides are paid differently than Eats deliveries are so they're noticing it differently?

<comment><AUTHOR> There are some anecdotes that it also happens on Rideshare, but I don't have a car so I can't verify until Uber allows me to pick up passengers on the handlebars of my bike

</comment></comment><comment><USER20> Middlemen are _always_ going to try to increase their take on both sides. It is the only way they can grow the profitability of their business because they can't add more value, they can only subtract.

<comment><USER21> Agree with the part about profitability, but middlemen can definitely add value.

I'd say that Uber's wide reach is valuable, the fact that they likely exist in the city you're visiting, the fact that they likely have enough cars to pick you up in under 5 minutes. These are valuable things that don't come from individual drivers or small taxi companies, but rather from big aggregators.

<comment><USER20> Small taxi companies could still have general dispatchers.

<comment><USER21> Sure, but that dispatch is a "middleman" for the service provider. The bigger that middleman becomes the more they may be able to offer. The dispatcher will take a cut of the taxi fares.

</comment></comment></comment></comment><comment><USER22> Not sure about UberEats but just two days ago a I took an Uber ride that was paying the driver about 5.50-6 euros instead of the usual 9-9.50 euros that the ride was usually worth, I felt bad about the driver and so I helped make up the difference in cash, directly to him. I know the sums and the difference itself don't seem that big in nominal terms but I live in Eastern Europe where the difference between 6 euros and 9 euros still counts for lots of people.

Anyway, interesting to see that that wasn't an isolated incident when it comes to Uber the company.

</comment><comment><USER23> Makes sense. Charging 30% off the top on orders wasn't enough, time to skim a little off the drivers too.

</comment><comment><USER24> Shouldn't the drivers be able to make a profit, without the tips?

</comment><comment><USER25> not sure why every driver isn't already using another mileage tracker app, at least for occasional trips to keep Uber accountable. theres dozens of those in the app store...

<comment><USER7> The question I would ask is how accurate all those other mileage trackers are? If they are based on GPS, then they have all the same issues with fewer engineering resources trying to correct defects.

The only mileage tracker that matters is the vehicle odometer on a stock vehicle with stock diameter tires with most of its tread. You'd need a device connected to the vehicle via ODB2 where you can press a bunch at the start and end of each trip.

</comment></comment><comment><USER26> This is good news, I thought the business model was to underpay drivers on 100% of trips.

</comment><comment><USER27> Why do these articles always reach the front page? Does hackernews hate Uber that badly? Or perhaps its profitable for news articles to always rag on them? Why is it profitable? Does everyone _want_ to see them fail?

They're no worse than your run of the mill tech company, so I suspect something odd is going on. I dislike corporations in general and want to see them play fair, but Uber changed the way I live life, and I'm constantly worried bureaucrats and angry business/tech nerds are going to regress us back to the taxi stone ages. We're just one law away from having to go back to hailing a cab with our thumbs and trusting their internal GPS.

<comment><USER28> Uber has changed your life for the better, by taking advantage of thousands of other people. Worrying about going back to the taxi Stone Age is actually worry about making things fair for those people.

<comment><USER29> Taxi drivers weren't treated fairly[1]. They were just abused by others instead of by Big Tech, so nobody cared. The appearance of Uber has actually allowed some progress in their labour rights[2].

[1] [https://www.nytimes.com/1995/04/09/nyregion/driving-a- taxi-d...](https://www.nytimes.com/1995/04/09/nyregion/driving-a-taxi- difficult-in-best-of-times-gets-tougher.html)

[2] [https://www.washingtonpost.com/news/wonk/wp/2015/10/29/labor...](https://www.washingtonpost.com/news/wonk/wp/2015/10/29/labor- boards-shift-in-legal-interpretation-could-allow-thousands-of-taxi-drivers-to- unionize/)</comment></comment></comment>


Show HN: Montage – 8 hand-picked playlists. 200 of YouTube's funniest videos - <AUTHOR> https://montage.watch/ <comment><AUTHOR> Hey everyone! This is a prototype I threw together with a friend. We've hand crafted 8 playlists with 200 of YouTube's funniest videos.

Some playlists people have really liked are Trump Bashing and Memes. We also have sketch comedy, memes, skits, shorts and more though.

We thought everyone could use a laugh right now.

Would really appreciate any feedback. Thanks so much!</comment>


RoboSat: feature extraction from aerial and satellite imagery - <AUTHOR> https://github.com/mapbox/robosat <comment><AUTHOR> Daniel from Mapbox here. Happy to answer questions or talk through design decisions. Interested to hear your feedback.

We are mostly focusing on making the process accessible to a broader audience in the geo space, building a solid production-ready end-to-end project.

There are more resources and a step-by-step guide for running on openly available drone imagery in Tanzania:

[https://www.openstreetmap.org/user/daniel- j-h/diary/44145](https://www.openstreetmap.org/user/daniel-j-h/diary/44145) [https://www.openstreetmap.org/user/daniel- j-h/diary/44321](https://www.openstreetmap.org/user/daniel-j-h/diary/44321)

<comment><USER2> Congratulation to you and the team. I have just one question in the world of tensorflowjs how do I run this project on a browser I was hoping to use this project to introduce high students to data science ?

<comment><AUTHOR> I haven no experience with TensorFlow.js. That said, using the RoboSat ONNX model exporter (rs export) you should be able to go from a trained PyTorch model to a portable ONNX protobuf, then from there to a TensorFlow model, and eventually to TensorFlow.js. At least that's how I would approach it. Keep me posted if you look into it and get it working, interesting use-case for sure.

<comment><USER2> Interesting, shoot me a email email@example.com

</comment></comment></comment></comment><comment><USER3> Have you released pre-trained models?

It would be pretty useful if you did, even as a just basis for transfer learning.

Also a description of the model that is used? I assume this is the code[1], which references [https://arxiv.org/abs/1806.00844](https://arxiv.org/abs/1806.00844), but the code doesn't seem to use WideResnet (although I really know Keras much better than PyTorch so I'm probably missing something.

[1] [https://github.com/mapbox/robosat/blob/master/robosat/unet.p...](https://github.com/mapbox/robosat/blob/master/robosat/unet.py)

<comment><AUTHOR> We haven't released pre-trained models yet. Mostly for two reasons: 1/ The PyTorch checkpoints depend on the specific Python model class. Even if you refactor only e.g. a MaxPool layer into a direct functional.max_pool function call, loading old checkpoints will no longer work. We have an ONNX model exporter now (rs export) which allows for self-contained and portable protobuf model and weight files. This workflow needs some more time and careful evaluation, though. 2/ The models for Tanzania I was working on in my spare time I can open up for sure. If there is community interest maybe we can come up with a publicly available model catalogue hosting ONNX models and metadata where folks can easily upload and download models. For our internal models and the data we extract we are thinking through a broader strategy since a lot of time and resources are going into creating and cleaning datasets, doing hard- negative mining, running multiple training iterations and so on. They're also bound to the Mapbox aerial imagery on specific zoom levels.

The model architecture is kept simple on purpose. It used to be an encoder- decoder U-Net'ish architecture which we trained from scratch. Recently ([https://github.com/mapbox/robosat/pull/46](https://github.com/mapbox/robosat/pull/46)) I switched out the encoder to a pre-trained ResNet, as proposed by Alexander Buslaev. It's a mix of the papers listed in the docstring at the top with a focus on simplicity and maintainability:

[https://github.com/mapbox/robosat/blob/1e687552fe9b254a14d55...](https://github.com/mapbox/robosat/blob/1e687552fe9b254a14d55d2825e8911bb812c63e/robosat/unet.py#L1-L10)

Internally we were also exploring a multi-class PSPNet but decided not to move forward with it right now: the RoboSat model is currently a binary model (feature vs. background) which makes a few things easier in practice, such as efficiently storing results which is needed when scaling it up e.g. to all of North America.

<comment><USER3> Personally I always try pre-trained models very very useful.

If I'm working in a new domain (which this is to me) then I prefer to get the workflow right (files in the right directories etc) before changing the NN architecture. It's a pretty big time investment to train a NN just to try it.

</comment></comment></comment><comment><USER4> Interestingly, we've taken the same approach to process historical document (like 18th Venetian manuscripts).

We even use a Unet architecture with a pretrained resnet50 encoder, and some postprocessing to go from prob maps to polygons, like this project does. Of course, we are much more limited than what you propose, but it is reassuring our side project took the same course as what bugger entities do.

[https://dhlab-epfl.github.io/dhSegment/](https://dhlab- epfl.github.io/dhSegment/)

</comment><comment><USER5> Hi Daniel, in your experience, what features is this model most suited for and with what granularity of imagery? For example, buildings/roads with landsat(30m)? Cars with 30cm resolution imagery?

<comment><AUTHOR> We are running it internally on our aerial imagery from the Mapbox Maps API. The zoom level even there depends on the feature you want to extract, for example z18 seems to work well for parking lots.

There is not a single feature this model is most suited for: you can add arbitrary features (e.g. tennis courts, swimming pools) in pre-processing and train your model. Then the imagery quality depends on your feature, for example it will be hard to impossible to spot swimming pools in Landsat imagery.

</comment></comment><comment><USER6> Very cool! Does anyone know any good global free satellite imagery datasets?

<comment><AUTHOR> Sentinel 2 data could be interesting for you. With its high refresh rate it can be used for change detection. The multi-band data is especially useful for adding more input channels to the model e.g. for water detection based on NDWI: [https://apps.sentinel-hub.com/eo- browser/#lat=52.51747&lng=1...](https://apps.sentinel-hub.com/eo- browser/#lat=52.51747&lng=13.31208&zoom=13)

I can also recommend [http://openaerialmap.org](http://openaerialmap.org) for playing around with openly available drone imagery. I did this last week as a side-project on my evenings for drone imagery provided by [http://www.zanzibarmapping.com](http://www.zanzibarmapping.com). Here is a step-by-step guide for giving it a try on the Tanzania drone imagery: [https://www.openstreetmap.org/user/daniel- j-h/diary/44321](https://www.openstreetmap.org/user/daniel-j-h/diary/44321)</comment></comment>


Retired USAF General Makes Eyebrow Raising Claims About Advanced Space Tech - <AUTHOR> https://www.thedrive.com/the-war-zone/31445/recently-retired-usaf-general-makes-eyebrow-raising-claims-about-advanced-space-technology <comment><USER2> "Technology to get an individual from anyplace on Earth to any other place in less than an hour" ... so, a mobile-platform-launched ICBM that you can climb into. I'd believe that the military would have developed that for that sake of some capability or other. It's not relevant to any plausible civilian application, however.

(The speculative SpaceX suborbital rocket thing, IMHO, is not credible evidence against my point. :) )

<comment><USER3> The problem is that you can't just launch a ICBM without risking Russia or China lobbing a few (hundred) back, regardless of the destination.

It is less a tech problem than a political one.

A stealth ICBM on the other hand... now that is a scary. If any other nations got wind of that we would have another nuclear arms race.

<comment><USER4> ICBM launches are detected via satellite primarily based on the extraordinary infrared output of a powerful rocket motor. A "stealth" ICBM would not really get you much, would it?

<comment><USER5> > A "stealth" ICBM would not really get you much, would it?

Stealth may help avoid interception during the midcourse phase, though:

[https://media.nti.org/pdfs/10_5.pdf](https://media.nti.org/pdfs/10_5.pdf):

> Midcourse Phase – "Largest Intercept Window"

> The midcourse phase allows the largest opportunity to intercept an incoming > missile. At this point the missile is no longer under power, so it follows a > more predictable path. Depending on the interceptor launch location, > multiple interceptors could be launched, with a delay between them to see if > the first ones were successful. Since the interceptor has a longer time to > engage, fewer interceptor sites are needed to defend larger areas.

> Unfortunately, a longer period in space provides an attacking missile the > opportunity to deploy countermeasures against a defensive system. However > the defensive system also has more time to observe and discriminate > countermeasures from the warhead.

But I think you're right that it a stealth ICBM wouldn't achieve as much as one would naively assume, and boost-phase detection would still invite retaliation.

<comment><USER4> When it comes to clever hypothetical changes to ICBMs, I remember one of the options floated late in the cold war was using a highly reflective coating that would hopefully ameliorate the effects of lasers (since we were taking interdiction with high-powered lasers more seriously then). I bring it up because I'm pretty sure it would be at cross purposes with a stealth coating.

I bet that given sufficient satellite coverage and image processing, ICBMs might remain _visible_ throughout most of their flight, making radar stealth a moot point. I hope the world will not go too far down the road of building out measures and countermeasures to update our nuclear weapons systems, but I think you'd have to add that possibility to the long list of possible countermeasures when doing your planning.

</comment></comment></comment></comment></comment><comment><USER6> With SpaceX doing booster landings now in full view and ICBMs and their ilk being well known for 50 years, is the claim that the tech to transport a person from any terrestrial A to B in under an hour being non-developmental (i.e practically feasible) really eyebrow-raising? I personally would be surprised if several ICBM-having militaries have not quietly developed something along these lines in the 70s, 80s, or 90s.

There is even tech flying today to make it relatively practical/economical now that the boosters are being reused, as we always speculated was technically feasible.

What's the big news here? Am I missing something?

I also assume that with the SR71 being as old as it is, the USAF has to have a couple of secret hypersonics by now that can get from any A to any B in the upper atmosphere in a few hours even non-ballistically.

<comment><USER7> Modern military ICBMs are solid fueled and thus can't really be used for human launches. They cause too much oscillation and vibration, and would effectively shake the crew to death. Some human rated spacecraft use solid fuel rockets as boosters only; the majority of thrust is delivered by liquid fuel engineers. So just having ICBMs doesn't really get you anywhere for delivering people.

</comment></comment><comment><USER8> What a horribly written breathless article. Does anyone know if a simple summary of the lecture available?

</comment><comment><USER9> Wow.... this reads as an amateur trying to clone Buzzfeed, and marry it with the enquirer...while only hiring writers from fiverr.

No organization, jumps all over the place. Very hard to get through, and my god the hype...it's everywhere.

</comment><comment><USER10> "...United States military and its industry partners may have already developed next-generation technologies that have the potential to drastically change the aerospace field, and human civilization, forever..."

I believe it. I remember how the Bin Laden raid was executed with stealth helicopters- low noise and radar profiles. Came out of nowhere. And wasn't there a report on how the Navy hinted at all the UFO sightings were from tech they had to make ghost jets?

<comment><USER11> They didn't came out of nowhere.

The US used "stealth" helicopters in Vietnam nicknamed the quiet one

[https://en.m.wikipedia.org/wiki/Stealth_helicopter](https://en.m.wikipedia.org/wiki/Stealth_helicopter)

It allowed them to send covert missions into north Vietnam, ironically it was initially developed for commercial civilian purposes as a quiet helicopter can be used for helicopter taxis and inner city travel more easily.

The US having stealth versions of the Blackhawk has been rumored since the 90's it was less about if they can make them but if there's an actual budgetary justification for them.

For the bin laden raid they used what essentially was scrapped prototypes and one of them crashed on landing during the raid.

RAM, low signature composites and acoustic improvements are hardly technologies that can described as which will drastically change the aerospace field.

<comment><USER12> I don't believe the helicopter crashed due to its stealth features. It was too close to a wall and had problems with lift.

<comment><USER11> It crashed because it was a prototype with stability issues, quite likely tied to some of its stealth characteristics including the muffling of the blade and it's weight distribution due to the use of composites.

The scene in the movie where one of the SEALs breaks through the fuselage when walking on top of the downed helicopter to plant the demo charge was taken from the redacted after action report and interviews with the team members so it's quite possible that a normal Blackhawk might have managed to perform a hard landing instead of a crash.</comment></comment></comment></comment>


Google Aims To Wrest Display Ads From Yahoo - <AUTHOR> http://www.nytimes.com/2009/09/18/technology/internet/18exchange.html <comment><USER2> EXCERPTS:

DoubleClick Ad Exchange, will greatly simplify the process of buying and selling display advertising, allowing many more publishers and advertisers to benefit from it.

But both in display advertising and in advertising exchanges, Google finds itself in the unfamiliar role of underdog. As one of the Web's biggest publishers, and a seller of ads on a network of top sites like eBay and hundreds of newspapers, Yahoo is the king of the display advertising business.

The new system will automatically allow hundreds of thousands of advertisers and publishers who now use Google's AdWords and AdSense systems to run their ads and ad space through the exchange.</comment>


The Dying Art of Mental Math Tricks - <AUTHOR> http://blog.tanyakhovanova.com/2015/06/the-dying-art-of-mental-math-tricks/ <comment><USER2> Is this still a relevant skill-set to be good at these days? I feel like it's a bit like writing cursive or being able to have good handwriting in general. It's just not that useful anymore unless you're in very specialized fields that require you to be good at mental math and even then how many situations are you in where you're put on the spot that you have to mentally solve something? There's probably more useful things to keep in your brain than these types of tricks.

I don't mean to be so negative though. I certainly think it's very fascinating and interesting just from a pure mathematical perspective. However we also have to consider the utilitarian perspective when asking "why" many people aren't good at something like this anymore.

<comment><USER3> My maths teachers at school, like probably everyone else's, loved to tell us that we wouldn't be able to carry calculators around with us all the time when we're adults.

The joke's on them. I carry a supercomputer with wireless access to the collective knowledge of humanity in my pocket.

More seriously, if we assume we only have limited time and capacity to learn things, these tools surely free us from learning mundane "tricks" and allow us to further explore more interesting subjects. Sure, an understanding of arithmetic is important, so that we can verify our tools are working. But once that's obtained, let's move on.

<comment><USER4> Yeah, except you look like a prick taking out your smartphone just to do some basic arithmetic.

It's weird to me that a class of people who like to puff about how intelligent they are are so proud of refusing to function at an incredibly basic human skill.

<comment><USER5> Showing your intelligence at full usually requires that you are not distracted. That is hard to come by these days.

I can calculate 16x180 in my head, but I would still pull out my smartphone to do it if the result is in any way important. Not because I'm lazy, but I know that the device won't make some silly mistake while doing it.

<comment><USER6> That's a trivial calculation to do, so I think it would be hard to make a mistake. I think you could have provided a better example.

Edit:

To the poster below, you only need the multiplication tables and basic addition. I don't see the big deal.

18 * 10 = 180

10 * 6 = 60

8 * 6 = 48

= 288

<comment><USER7> 12x12 is the max for most memorized multiplication tables (at least in the US). 16x18 is going to require some actual mental work that is prone to errors.

<comment><USER8> For computer people, 16×18 is easily split into 16×20 - 16×2, which in turn is 320 - 32. If you don't know instinctively that 16×2 is 32 it might be a bit harder though.

<comment><USER6> Or a better way for us programmers:

16 * 16 = 256

16 * 2 = 32

256+32 = 288

<comment><USER9> Even better:

16 * 18 = (17-1)*(17+1) = 17^2-1 = 289-1 = 288.

Provided of course you know your squares.

<comment><USER6> Ah that's a good one. I had powers of 2 in mind.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER10> If you want to practice skills like these, try:

Street-Fighting Mathematics [1] and The Art of Insight in Science and Engineering by Sanjoy Mahajan (MIT) [2].

Free downloads via: [1] [https://mitpress.mit.edu/books/street-fighting- mathematics](https://mitpress.mit.edu/books/street-fighting-mathematics) [2] [https://mitpress.mit.edu/books/art-insight-science-and- engin...](https://mitpress.mit.edu/books/art-insight-science-and-engineering)

<comment><USER11> Thanks!

</comment></comment><comment><USER12> This Android alarm clock has dramatically increased my speed and ability to do simple arithmetic: [https://play.google.com/store/apps/details?id=com.alarmclock...](https://play.google.com/store/apps/details?id=com.alarmclock.xtreme.free)

It allows the user to set an alarm that can only be turned off by solving math problems. You can imagine how quickly one's brain improves at this task when the reward is a snooze or a removal of a blaring alarm at 5 in the morning.

<comment><USER13> Has it decreased the median delay between the first alarm and you getting out of bed?

<comment><USER12> I'd say so. The only way it ever seemed to really work was when I set more than four math problems on the hardest level.

</comment></comment></comment><comment><USER14> Cool article and I love the writing style with subtle historic comments like the last sentence here:

"""I was good at mental arithmetic and saved myself a lot of money back in the Soviet Union. Every time I shopped I calculated all the charges as I stood at the cash register. I knew exactly how much to pay, which saved me from cheating cashiers. To simplify my practice, the shelves were empty, so I was never buying too many items."""

</comment><comment><USER15> Reminds me of yet another cool story from Richard Feynman about beating an abacus salesman with mental arithmetic: [http://www.ee.ryerson.ca/~elf/abacus/feynman.html](http://www.ee.ryerson.ca/~elf/abacus/feynman.html)

<comment><USER16> That is a very cool story. Feynman tells through his books a lot of this tricks to do arithmetic.

</comment></comment><comment><USER17> Mental math is extremely useful when making financial decisions, especially because often you have to think on your feet to decide against an impulse buy and salesmen are actively trying to confuse you. That said schools have never done a good job of teaching finance basics, such as rules of thumb for calculating compound interest, or even what a reasonable interest rate is (hint: inflation is usually 2-3%, while the stock market usually grows at 6-7%).

<comment><USER18> If you ever need more time "to think and decide" (and feel that you are being rushed) simply ask a question (almost any question will do but one that isn't a simple yes or no is better obviously) or make a statement and use that time to give more thought to what you are trying to make your mind up on.

</comment></comment><comment><USER6> My favorite trick is one my father taught me after I first learned multiplication in school. The result of any two digit number mutiplied by 11 can be found by taking the sum of the two digits and inserting it between the original digits.

Example:

54 * 11 = 5(5+4)4 = 594

In case the sum is greater than 9, carry the tens digit to the first digit of the result.

Example:

56 * 11 = 5(5+6)6 = (5+1)(1)(6) = 616

I used to challenge my fellow students to see if they could find the result faster using a calculator. They thought I was some genius.

</comment><comment><USER19> I was wondering why last digit of 5th power is the same as original number and the answer [1] is to look at x^5-x which is x(x²+1)(x+1)(x-1) and prove that it is divisible by 5 and 2 (by going through the possibilities) so it must be divisible by 10. Or [2] use euler theorem. There is a comment that (spoiler) the most general form is "The last digit of, any integer and its nth power, are the same, where n=4k+1."

[1] [https://answers.yahoo.com/question/index?qid=20071020225048A...](https://answers.yahoo.com/question/index?qid=20071020225048AAfcZr6)

[2] [http://www.johndcook.com/blog/2015/07/04/when-the-last- digit...](http://www.johndcook.com/blog/2015/07/04/when-the-last-digits-of- powers-dont-change/)

</comment><comment><USER20> I bet this art is not dying, but actually flourishing like never before.

The sheer amount of information in the form of websites, books, videos and so on should be a pointer. I mean just google "mental math tricks"..

It's true that we can offload complicated brain tasks like number crunching to computers, but people do a lot of hard things also because the process gives them satisfaction. They climb mountains and walk thousands of miles not because they want to get somewhere, but because it's exciting and hard.

For this reason, I think people will continue to study and invent new mental math tricks...

More people, more free time, almost infinite info available... No, this art isn't going anywhere ;)

</comment><comment><USER21> My favorite is still the multiples of 9 by putting down one finger. It amazes me.

Of course it only works with a full set of fingers, but still.

<comment><USER22> Multiply by x by ten, substract x?

<comment><USER23> I was wondering why no one was suggesting this, isn't this the most obvious one?

</comment></comment></comment><comment><USER24> Two excellent books on the subject are _Secrets of Mental Math_ by Arthur Benjamin (for beginners) and _Dead Reckoning: Calculating Without Instruments_ by Ronald Doerfler (more advanced).

The _Mind Your Decisions_ blog ([http://mindyourdecisions.com/blog/tag/mental- math/](http://mindyourdecisions.com/blog/tag/mental-math/)) has a lot of neat mental math tricks, but they're not really organized into a unified presentation there as in the books above.

</comment><comment><USER25> I memorized a bunch of these for high school math competitions. You got very familiar with squares up to 100, prime numbers up to 100, converting fractions and repeating decimals. A sample test from back in the day: [http://www.texasmath.org/DL/NS/NS9394.pdf](http://www.texasmath.org/DL/NS/NS9394.pdf) Of course, I've forgotten most of the tricks because they were so specific to the test.

</comment><comment><USER26> > John H. Conway is a master of mental calculations. He even invented an > algorithm to calculate the day of the week for any day. He taught it to me, > and I too can easily calculate that July 29 of 1926 was Thursday. This is > not useful any more. If I google "what day of the week is July 29, 1926," > the first line in big letters says Thursday.

It takes me under 10 seconds to do that one, which is as fast or faster than opening a new window and Googling, especially on mobile, so I think this is still useful.

For the contribution from the year I use my own algorithm that I find faster than Conway's algorithm. Here's mine. In the following, assume a/b means floor(a/b), and odd(k) is true iff k is odd. In a C-like notation, my expression for the year contribution is

       -(y/2 - (odd(y) ? 1 : 0) - (odd(y/2) ? 3 : 0) mod 7

For example, for 26, that gives -(13 - 0 - 3) = 4. The way I would do this mentally is to note that 26 is even so I'm not going to have a subtract 1 step later, divide it by 2 to get 13, note that is odd so subtract 3 giving 10. I then do the negation mod 7 by simply noting how much I have to add to reach a multiple of 7, which in the case is 4 (10 + 4 is a multiple of 7). That gives the final result, 4.

My inner dialog would be "26...13...10...4".

If we were doing year xx27, it would go like this "27...13...10...9...5".

xx28 would go "28...14...0".

xx29 would go "29...14...13...1".

That illustrates all four cases.

I find this simpler than Conway's method, which is (y/12 + y%12 + (y%12)/4) mod 7, although I might find Conway's faster if I would get off my lazy ass and memorize the multiples of 12 up to 100.

I also find it simpler than the odd + 11 method, which is:

      T := y + (odd(y) ? 11 : 0)
      T := T/2
      T := T + (odd(T) ? 11 : 0)
      T := -T mod 7

Odd + 11 has the nice property that you only carry one number of state, whereas mine requires carrying whether the initial year was odd or even. However, it can start out increasing the number you are working with, which slows me down a little with years near the end of a century. Mine always starts out dividing by 2, and then might subtract, so is always going toward lower numbers.

One could remedy this in odd + 11 by changing the first step to the equivalent

      T := y - (odd(y) ? 17 : 0)

when dealing large y values, at the cost of having to do a -17 instead of a +11. (These are equivalent because of the 28 year cycle in the pattern of days of the week within a century. You can start off any of these Doomsday methods by adding 28 to or subtracting 28 from the year. So, if you have an odd year and subtract 28 before starting, and then add 11 under odd + 11, that is the same as subtracting 17 from the original year).

While I'm here, there is one other place that can use improvement. The Wikipedia article on the Doomsday rule gives the rule for calculating the century contribution when using the Julian calendar as:

      6 x (c mod 7) mod 7 + 1

That's fine, but if you just blindly follow it you'll be doing more work than you need to. It can be simplified to this simple expression:

      -c + 1 mod 7

For example, let's do June 15, 1215 (date of the Magna Carta) on the Julian calendar.

Century component: -12 + 1 mod 7. I'd do this by noting that I have to add 2 to 12 to get a multiple of 14 (that's the -12 part), and adding the 1, so I'd mentally just go "12...2...3". The century component is 3.

Year component: "15...7...4...3...4". Year component is 4.

Month component for June is 1, and day is 15 = 1, so we have 1 + 1 + 4 + 3 = 2 = Monday. For the month component, I just memorize it using Conway's suggested mnemonics, which gives 6, but since the month component is subtracted I want the negative of that, and I use the same trick I use everywhere of simply noting what I have to add to reach a multiple of 7. 6 + 1 = 7, so that's where the one comes from.

Trivia: that date is also a Monday on the Gregorian calendar.

A couple other things that might be useful to those wanting to play around with doing calendar calculations in your head.

If you want to go backwards on the year component, and find a year with year contribution M, the first year of the form 4N with year contribution M is (3M % 7)x4.

For example, suppose I want to know a year this century (century factor is 3 for 20xx) where Christmas falls on a Tuesday. The month contribution for December is -12 = -5 = 2. So I want 3 + M + 2 + 25 = 3 mod 7. Thus, I want M = 1. Plugging that into (3M % 7)x4 I get 12, so 2012 has Christmas on Tuesday.

That's already past. I want to know upcoming years with Christmas on Tuesday. We can make use of another pattern to deal with that. The next year after Y within the same century that has the same year contribution is:

       Y + 6  if Y is of the form 4N or 4N + 1
       Y + 11 if Y is of the form 4N + 2
       Y + 5  if Y is of the form 4N + 3

So, starting with a year Y of the form 4N, we have these years all have the same year contribution:

       Y, Y+6, Y+6+11, Y+6+11+6

and then it starts over again at Y+28, which is Y+6+11+6+5.

Using this, and starting from 2012 (a 4N year), we get that Christmas will also be on Tuesday on 2018 (a 4N+2 year = 2012+6), 2029 (a 4N+1 year = 2018+11), and 2035 (a 4N+3 year = 2029+6), and then the 28 year cycle repeats starting at 2040 (a 4N year = 2035 + 5 = 2012 + 28).

An alternative to the (3M%7)x4 approach for going from M to Y is to just memorize this:

      M   First Y for M
      0   0
      1   1
      2   2
      3   3
      4   9
      5   4
      6   5

and use the 28 year cycle to jump up by multiples of 28 if you are interest in a Y for your M that is farther into the century, and use the 6,11,6,5 pattern to move around in shorter ranges.

<comment><USER27> I also have my own algorithm for computing the day of the week, and I think that you're doing it the hard way. Of course, if it works for you, no problem.

My technique:

      day_of_week = (year_day(Y) + month_day[M] + D - leapyear(Y,M)) mod 7

      year_day(Y) = let Y' = Y-1900 (or Y-1984) in Y' + trunc(Y' / 4)

      month_day[] = { 0, 3, 3, 6, 1, 4, 6, 2, 5, 0, 3, 5 }

      leapyear(Y,M) = 1 if M is Jan or Feb in a leap year, else 0

The year_day() is a constant for any year; in 2016, it's 5. The month_day[] table is easy to memorize in an inverted form that groups all the months that start on the same of the week in non-leap years:

      0: Oct, Jan

      1: May

      2: Aug

      3: Feb, Mar, Nov

      4: Jun

      5: Sep, Dec

      6: Jul, Apr

And that's it. Today (13 Jan 2016) is 5 + 0 + 13 - 1, or 17 which is 3 mod 7, or Wed.

(EDITED to fix line spacing issues.)

<comment><USER28> For year_day(2016), I get 145 (using the 1900 option). Can you check your formula?

<comment><USER27> 145 = 5 mod 7, and I'll often reduce terms mod 7 when doing the math mentally.

EDIT: I mean of course that 145 is equivalent to 5 (mod 7).

<comment><USER28> Thanks! I can use this now.

</comment></comment></comment></comment></comment><comment><USER29> Here's a cool site for practicing mental math (only 4 operations involving numbers up to 12 though): [http://www.speedsums.com](http://www.speedsums.com)

</comment><comment><USER30> Naturally there is a Dover book that covers this topic too:

[http://store.doverpublications.com/048620295x.html](http://store.doverpublications.com/048620295x.html)

</comment><comment><USER31> "I was good at mental arithmetic and saved myself a lot of money back in the Soviet Union."

This reveals a weakness in western education. People in the former Soviet Union learned a lot of mathematics in the traditional way (a mixture of clever mental calculating skills and a good grounding in theory) simply because they had no alternative and there were many problems to be solved requiring higher math skills.

Americans, on the other hand, (as well as being famously lazy about math) now rely almost completely on calculators and computers and are gradually abandoning both mental calculation and deep theory in mathematics. An EMP will someday zap all our electronics and we'll get our comeuppance, and we'll have to try to remember exactly why the integral of x^2 is x^3/3 + constant.

As I sailed solo around the world 25 years ago I spent a lot of my free time practicing mental math. One day in Israel I read my receipt at a restaurant and realized the waitress had inflated the cost by performing a creative kind of addition. I corrected her figures, lectured her, and paid the difference as a tip. It occurs to me that she could get away with creative addition with 99% of people, even well-educated people, because nearly no one checks the addition on a receipt.

Hans Bethe and Richard P. Feynman were both formidable mental calculators, at a time when that skill was valuable. There are stories about how (when they were both at Los Alamos) they would have contests to see which could produce the quickest result using somewhat different methods. This was at a time when a matrix calculation required a roomful of "calculators" sitting at mechanical adding machines all day long, sometimes for weeks, estimating the yield of a nuclear explosion.

<comment><USER32> >and we'll have to try to remember exactly why the integral of x^2 is x^3/3 + constant. //

I could never remember such things when I was younger (it's worse now), which was why I loved maths so much because when I couldn't remember - provided I could remember basic principles - I could work it out.

So as long as we know the basic principles of integration we won't need to remember that particular sum.

<comment><USER8> I am terrible with remembering a bunch of facts, but I'm pretty good at working things out from basic principles. It's funny because many of my friends look at me figuring something out from basic principles and they think it looks like so much work – then they go back to taking a few hours to memorise things they could just as well work out from basic principles! Who's doing the work now?

I guess we both are, only I postpone it to when I really need it.

</comment></comment></comment><comment><USER33> Let's play Numberwang! [http://youtu.be/qjOZtWZ56lc](http://youtu.be/qjOZtWZ56lc)

</comment><comment><USER34> If you find Speed Maths interesting, you'll probably want to check out Trachtenberg's "Speed System of Basic Mathematics" book:

[http://www.amazon.com/Trachtenberg-Speed-System-Basic- Mathem...](http://www.amazon.com/Trachtenberg-Speed-System-Basic- Mathematics/dp/4871877094)

</comment><comment><USER35> I didn't read all the comments, so this might have been said already. But I think there are some professions where quick mental arithmetic provides an edge. At one point I was learning how to play professional poker and while I had the common situations memorized, I'd calculate the less common situations. There are more use cases than just poker, chance estimation in general, or in a casual discussion where the other might not have a lot of patience.

Compared to the old days however it has been in decline, but just like writing -- even cursive writing -- it still has its uses (cursive writing: exposing yourself to multiple ways of writing allows for a more fluent writing style in my experience).

</comment><comment><USER24> The First Sunday Doomsday Algorithm is the simplest way to calculate the day of the week for any date in your head.

[http://firstsundaydoomsday.blogspot.com](http://firstsundaydoomsday.blogspot.com)

It brings together a bunch of great mnemonics, like the new "odd+11" rule for calculating the 2-digit year code, as well as Conway's classic "I work 9-5 at the 7-11" for the month code.

</comment><comment><USER36> like any science, math is more about problem solving skills versus the rote action, and mental math nowadays is nothing more than a 'fun' game. However some insight can be gained from mental math tricks that help solve deeper problems (log addition versus product computation for bayesian nets to avoid overflow), but the cost of teaching these tricks conveys to students that the trick is the goal, missing the point of mathematics as a science. At worse teaching such tricks results in us losing otherwise amazingly talented future mathematicians because they weren't particularly good at the 'tricks' part.

</comment><comment><USER37> Anyone who has undergone a gauntlet of "cargo cult" style technical interviews knows full well that these "tricks" arent a dying art - they sometimes determine eligibility for a job.

</comment><comment><USER38> Looking at this thread there is clearly a community (overlapping significant portions of the HN community) where this is not a dying art.

</comment><comment><USER39> Are there any known resources for learning math tricks like the ones mentioned in the blog post? Perhaps a book...

<comment><USER40> Secrets of mental maths is one book that I heard of a long time ago.

Note: didn't read it myself.

</comment></comment><comment><USER41> Indeed. In my UK primary school in the 1960s, 'Mental Arithmetic' was a distinct curriculum subject.

</comment><comment><USER42> It took me a couple seconds, but I did this mentally:

75^2 = (70 + 5)^2 = 4900 + 2 * 70 * 5 + 25 = 5600 + 25 = 5625

<comment><USER43> You can also do this by (ab)using the "square of a number close to 50" trick. Take 57^2 for example: this is the square of 50 plus 100 times the difference of the number from 50 plus the square of the difference of the number from 50, which is 2500 + 100x7 + 7^2, or 3249. For 43^2 it would be 2500 + 100x-7 + (-7)^2, which is 2500 - 100x7 + 49, or 1849.

With 75, that's 2500 + 100x25 + 25^2. Hopefully you've memorized that 25^2 is 625, which makes this an easy 2500 + 2500 + 625, or 5625.

<comment><USER42> You're saying that

      x^2 = (50 + (x-50))^2
          = 2500 + 2 * 50 * (x-50) + (x-50)^2
          = 2500 + 100 * (x-50) + (x-50)^2.

I'd be a little worried about the number of double-digit squares in this method. I can't do them as easily as single-digit squares, which using the multiple of 10 closest to the number ensures.

For example, I'd have to use another trick to calculate

      13^2 = 100 + 2 * 10 * 3 + 9 = 169

in the middle of the calculation for

      63^2 = 2500 + 100*13 + 13^2.

But

      63^2 = 3600 + 2 * 60 * 3 + 9 = 3969

is almost immediate.

<comment><USER43> That's why it's an abuse of the "number close to 50" trick. It really is meant for single digit differences from 50. The only reason it works for 75 is because hopefully 25^2 comes up often enough that people have it memorized. I know I memorized it long ago after seeing it a number of times: "twenty-five times twenty-five? six twenty-five" is easy for me to remember. If people don't have 25^2 memorized, the trick kind of falls down.

Otherwise, you're right. You can break down the square of _any_ number into (x+y)(x+y) = x^2 + 2xy + y^2. For 50, the "2x" term equals 100, and multiplying by 100 and adding to 2500 is dirt simple for anybody to do.

<comment><USER44> 96 81 676761</comment></comment></comment></comment></comment>


Ask HN: Best CRM/BD-mgmt product for 4-person startup? - <AUTHOR> HN:
We are three engineers and one sales. We are new and small - and need to start capturing our market, leads, vendors, etc - in something more complex than excel.
What tool would you recommend (freemium at this point preferred) - or should we just continue to use excel?
What tools are you using to track your market, contacts, leads, prospects etc that isn't a tool that is trying to service only Big Co.?
Any advice apreciated. <comment><USER2> Google Sheets (I like Excel, but Sheets is better for collaboration).

No reason to get caught up on tools right now.

</comment><comment><USER3> Airtable? Your needs will change as you grow so you want something flexible.</comment>


IPhone satisfaction at 75%; closest competitors Samsung, HTC at 47% - <AUTHOR> http://www.changewaveresearch.com/articles/2012/smart_phones_20120109.html

<comment><AUTHOR> If you compared the iPhone with Samsung and HTC premium devices at similar prices as the iPhone, I believe the results would be slightly different. Detailed statistics might be in the full report, but it's $499.</comment>


Voting Rings: How Insiders Game User Generated News - <AUTHOR> http://www.bothsidesofthetable.com/2010/09/01/mafia-sourcing-the-insiders-game-of-user-powered-news/

<comment><USER2> How many people here ever click on "new"? How many stories just disappear without hitting the front page? How many accounts need to be involved to make a particular story get to the front page?

I'm sure that the answers respectively are, "rather few", "the vast majority" and "not many". And there you have the raw ingredients for a voting ring to form. As a matter of principle I would never be involved with such, and I have a natural dislike for anyone that I think is. But the ingredients are there.

More than that, you still have a popularity effect. People who vote on new articles have to prioritize what they read in some fashion. Speaking personally, it is natural to choose to look at articles with interesting titles, or which are submitted by someone you recognize as being a consistent source of good content. Therefore if someone like patio11 submits an article, it has a significant advantage. As does anything involving YC. (Of course promoting YC is the whole point of this site, so I don't mind that at all. And I'm guilty at looking at content from people I trust before content from people I've never heard of.)

Memory says that jacquesm mentioned once that he had turned down an offer of money to post certain articles from companies that were looking for good pr. (I don't swear that I correctly remember who it was.) He may have turned them down, but I'm sure they asked again, and if they asked around enough I'm sure that they found a taker. And if so, then you have the dark side here on HN.

<comment><USER3> Why not simply mix some 'new' randomly into the front page at some ratio? If one or two of the stories in the front page were (different) new stories for each visitor, you'd solve the "front page or bust" problem.

You'd sacrifice a bit of "quality" from the front page, at the gain of a more variety and more exposure for new stories - entirely tunable by the ratio.

<comment><USER4> Or display both in two columns. Frontpage on the left. New on the right.

<comment><USER3> Well, the idea would be that the casual viewer couldn't distinguish the 'new' from the front page and so would treat them the same.

Otherwise people will ignore new as they do now.

(Point score could be left off of the front page to help this).

<comment><USER4> I think the problem is not that people are wilfully ignoring it, rather it's just not prominent enough.

When I open HN, I am immediately seduced by an interesting headline (or point score) of a frontpage story. I don't have time to make a conscious decision to visit /newest. There's no way it's getting precedence over _"12 ways to speed up your Erlang programs with NoSQL"_.

If new and the frontpage got equal treatment, then I'd be seduced by interesting headlines of frontpage and new stories equally. Meaning the good new stories would have a better chance of being upvoted.

I wouldn't like to see frontpage and new stories merged into the same list, since a great deal of new stories are spam or otherwise devoid of interest.

</comment></comment></comment></comment></comment><comment><USER5> It's interesting to me that Kuro5hin in its heydey had relatively few problems with voting rings, despite having a purely voting-driven front page. There are probably some reasons involving community size and dynamics, but my guess is that the biggest one is the fact that the site was organized around submission of original articles to Kuro5hin, as opposed to submission of links. That raises the buy-in stakes beyond what people only interested in promotion are willing to spend time on, as well as lowering the potential gains from promotion (you got your article read, but directly on k5, not via traffic to any monetizable endeavor of yours). The fact that all votes were public may have had an effect as well, making any sort of collusion easier to spot.

<comment><USER6> It's also what made K5 in to a huge echo chamber.

<comment><USER5> I guess I didn't find that to be the case, any more than any other forum, at least. In what ways was K5 more of an echo chamber than, say, HN is?

<comment><USER6> If you write stuff for your 'own' audience of the K5 members, which will then write stuff as well for you to comment on and so on it's different than if 90% or more of the submitted articles is about stuff from the outside.

It brings in fresh blood, outside perspective and avoid inbreeding.

<comment><USER5> Ah, I guess that's the part I actually find much better. There's a certain community aspect where people are actually talking to each other, addressing an audience, that leads to much deeper engagement and discussions imo. That's also the feature of good mailing lists, BBSs, and Usenet groups I like best (though there are plenty of bad ones). The link-site thing seems too disjointed, and imo actually leads to _more_ of an echo-chamber effect, because people end up having to pattern-match based on superficial things like headlines. So we get lots of random submissions that seem superficially about hackerdom or startups, but less sustained engagement. I mean, I personally find HN _much_ more echo-chambery than K5 at its peak was. Perhaps personal preference.

<comment><USER6> Interesting. You've convinced me to re-visit K5 to see what it's like there now.

<comment><USER5> Haha, I wouldn't suggest it. I still post there, but it's basically a dive bar of old regulars and some old trolls (who are now a bigger proportion, but have been around long enough that they're sort of endearing, like the local drunk). Very little technical content, and nobody ever writes/submits stories any more, although there is occasionally technical stuff in the diaries (Luke from prgmr.com still posts some stuff there). I think early 2000s was its peak, it was on life support by around 2006, and from 2008-present it's been the walking dead.

An interesting question (to me) is what killed it. One might be that Rusty Foster increasingly lost interest in too much active sysadminning, and eventually added a $5 registration fee, which he thought would raise the quality of the userbase, but actually ended up completely killing any new registration. Another might be the rise of blogs. Although I like the submit- to-K5 model, blogs _do_ make it a lot easier to just post on your personal blog and link somewhere if you prefer. I think there are especially economic incentives to write good content on your own blog rather than on a community site these days (you can make a little money from even a personal blog, get pagerank/prestige from it if it's attached to other projects, etc.).

Of course, that's exactly the part I'm ambivalent about, even though I do it too. I think something's lost when you go from 100 people discussing in a community (whether it's a site or a mailing list) to 100 people each trying to build their personal brands.

<comment><USER6> So, I did take a look. It's mostly dead. Pity!

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER7> HN may have voting rings, but it still works because it's a niche site, and hackers have strong Internet BS detectors that counter spam/phishing/linkjacking/other mischief relatively effectively. People on HN may be killing time, but the majority still have some quality standards for what they want to read. Gaming HN isn't worth as much because A) there's fewer people, and B) you have to work harder to game it. Other niche sites can easily share this quality.

But for a site like Digg that wants to be the biggest social news site, it's just a race to the bottom. Gaming Digg just requires a tabloid-editor mentality where you figure out the quickest thing that will grab peoples attention and then boost it to the front page.

</comment><comment><USER8> YC is already one giant mafia, if you'd like to think of it that way. I'm sure YC classes vote each others' stuff up.

I'm wondering what the recently implemented voting ring detection reveals. Are they all clustered by YC class? Are there overlaps? Or is there an outside group moving the articles up?

</comment><comment><USER9> When you build a site with user submitted content and voting, you have two immediate problems you need to solve before you can even get started:

      - How are you going to deal with spam
      - How are you going to deal with gaming

They're actually related problems, since the aim of both is to drive people to a given website. Since that's demonstrably valuable in terms of cash money, it's an absolute certainty that people will try to take advantage of it.

You really need to bake something in to handle it from the word go.

<comment><USER10> What you need to truly defeat this sort of spam is personalization, AKA recommendation,

If the top news stories are personalized to your interests, it is more difficult to game the system.

In particular, consider this scenario: I get a news result from a voting ring, and it ranks high because they all voted. But then I downvote the article because it is not interesting to me, Afterwards, the voting ring's weight is diminished in my personalized news feed. Hence, they cannot artificially rank articles for you,

I would argue that without some personalization, it is impossible to 100% avoid spam. Because if you treat there as being one objective lense, it is hard to discriminate between legitimate overlapping interests and colluders who share their authority.

<comment><USER9> Indeed, though that would only fix it for the small percentage of users who are (a.) logged in, and (b.) vote things down.

It wouldn't work on me, for example, because I hardly ever vote on anything here. In the 3 years I've been around I can't imagine I've actually voted _down_ more than a half dozen times.

<comment><USER11> You don't have to be logged in - just give them a long-term cookie when they show up on your site and it still works. And if you aren't voting anything down, you wouldn't be the kind of person who would need such a website in the first place.

<comment><USER9> _And if you aren't voting anything down, you wouldn't be the kind of person who would need such a website in the first place._

You lost me there. You're talking about this on a site that doesn't even _allow_ its users to downvote stories. And you're talking to a power user of that site, who just told you he doesn't ever downvote things. HN is a culture of voting _up_ things that are good, and, rarely, downvoting things that are distracting from the conversation. That's one of the reasons it's so good.

As to cookies for non-logged in users, they don't really help anything. Sure, you could consider every clickthru as a 'vote' for personalization purposes, but it would likely just fill a user's feed with poorly titled things and clickbait. Probably more than half the articles I click through on get closed immediately without reading. I wouldn't want to optimize my view to include more of that.

<comment><USER12> >And you're talking to a power user of that site, who just told you he doesn't ever downvote things.

As an aside, what makes you a "power user"?

<comment><USER9> Same thing that makes you one, brother. 1000 reputation points and the equivalent of $10k in otherwise billable hours squandered on this site.

<comment><USER12> I'm going to be lording it over the hoi-poloi now, "I'm a power user".

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER13> I'd bet there are voting rings on HN. Perhaps not as bad as was on Digg. But I'm sure it's here. PG made a comment about it the other day, offhand, in something about getting some code/idea help about fighting it.

<comment><USER14> Since many people have dynamic IPs, I think tracking geolocation patterns of the first 10-ish votes would be enough to distinguish suspect cases and eventually put them 'on-hold' (HN dosen't really need to get stories on the front page as soon as possible, it's not exactly a breaking news site).

<comment><USER15> Since people have to be logged in to vote, there is a much easier solution:

Count votes from new users lower.

And count early votes from users often voting on articles posted by a particular person lower.

It can be refined quite a bit...

<comment><USER14> True, but the problem with voting rings is that links may be submitted by different participants to the ring each time, and if they all have genuine high karma, that is difficult to track down.

</comment></comment></comment></comment><comment><USER16> There's a fine line between a couple dozen guys on IRC with similar interests and an actual voting ring. I'm not sure where one concept stops and another starts. I guess if you demanded money for voting, that'd obviously be bad. But if you IM'ed a couple dozen friends about a cool new link you saw? It gets fuzzier.

I have noticed voting trends by time of day on HN. I've also noticed what appears to be auto upvoting and downvoting based on the submitter. But I'm just an outsider, so what do I know? Up until recently, I have always assumed such activity to be more demographically-based. I am slowly beginning to have my doubts, though.

The interesting point about HN is, at the end of the day, this is PGs site. Maybe he decides he wants articles about squirrels. So we get articles about squirrels. Maybe he decides site X is trollish. So we get no stuff from site X.

It's been called a "benign dictatorship". Meh. Sounds a bit like "jumbo shrimp" to me. Even though HN isn't what it used to be, I still visit.

</comment><comment><USER17> oooooh, i'm so scared... but excuse me, I've got to make a few 1000 electric sheep so I can get some traffic to my blog...</comment>


Give HN: Take over my Apple video site? - <AUTHOR>

My hobby is http://6colors.net
HTML5 video all about Apple and Apple related stuff. Vintage footage, current footage plus hundreds of gb of footage I dont even have encoded yet.
I cant host it any longer as I am planning to move  out in the yonder where there wont be sufficient Internet.
Anyone interested in taking it over? E-Mail in profile.
Currently the site is about 312GB + 97GB of videos encoded ready for the site + 180GB of raw footage.
The site uses HTML4, CSS, JS, MySQL. I wrote a BASH script that takes the raw footage and encodes it into the various supported browser formats (mp4, ogv, webm).
Why is the site so big? I'm a big backup crazy. I store the original footage + mp4 + ogv + webm versions for each. <comment><USER2> I apologize – I'm on mobile, so I can't really look carefully right now, but if you don't have time to run the site, perhaps you could convert it to something with lower maintenance, like YouTube channel?

<comment><AUTHOR> Yeah that is an option, but I enjoyed doing all of this myself.

<comment><USER3> On that same note: Vimeo does allow download links to the source files (assuming its a distribution format like MPEG4 and not intermediate codecs designed to be used by Final Cut, Avid etc). In the interest of preservation, it'd allow users to download the sources as well, would be more easily viewed (and embeddable).

I do see value in hosting outside of Vimeo/Youtube as the likelihood of having content DMCA'ed is a looming threat.

<comment><AUTHOR> Folks from Apple IP's visit the site everyday (and have for years!) I even get some e-mails saying Thank You for making this available.

Right now I host this on a simple desktop computer running CentOS (an AMD Athlon X2 with 32gb of RAM, Mirrored 1TB hd)

I tried hosting it on a VPS and well, performance was so bad.

</comment></comment></comment></comment><comment><USER4> Would love you to put the footage up on YouTube. Could actually pay for your hosting with Adwords depending on the license and copyright issues with all your videos. Or sent them to an archive.

</comment><comment><USER5> We would happily host your footage at Viddme - [http://vidd.me](http://vidd.me)

</comment><comment><USER6> Consider giving this material to an interested archive. This is what archives are for.

</comment><comment><AUTHOR> For some reason I cannot edit this anymore. It is HTML5.</comment>


Cambridge, MA City Council adopts resolution to commemorate thirty years of GNU  - <AUTHOR> https://www.fsf.org/blogs/community/cambridge-ma-city-council-adopts-resolution-to-commemorate-thirty-years-of-gnu

<comment><USER2> There's really no city like Cambridge. The other day I saw a subway ad for genetic research that was geared toward everyday commuters: "Everyone deserves a chance to break through...Take your research to the next level..."

</comment><comment><USER3> If the Cambridge City Council were even remotely serious about promoting innovation, they could at least stop locking out ISP competition. Might go a lot further than empty commemoration.

<comment><USER4> Can you link to some kind of evidence of that? My understanding is that RCN, Verizon, etc. are just not interested in expanding in to Cambridge.

edit: Here's what the city has to say, from[http://www.cambridgema.gov/consumercouncil/cambridgecableinf...](http://www.cambridgema.gov/consumercouncil/cambridgecableinformation.aspx):

"Comcast is currently the only cable operator that has sought a license with Cambridge. The City of Cambridge has approached other operators, more than once, about seeking a license to operate a cable TV system in Cambridge, but they have informed us that Cambridge is not currently part of their business plan; however, City officials stand ready to negotiate with any willing operator."

<comment><USER3> Right, so the relevant point is what "seeking a license" actually entails. RCN works in neighboring Somerville and FIOS is all over greater Boston. Cambridge is a bit less dense than Somerville but generally more affluent, so there's no good reason that RCN wouldn't expand into it. It simply doesn't make sense to say that all these companies aren't interested; otherwise why would they have approached the council in the first place? What would it even mean for them to have sought a license and then decide it's "not currently part of their business plan"? There's nothing particularly special about Cambridge, but for a city its size and with its access to the backbone, there's a very odd lack of choice.

I think a key to the issue is:

> City officials stand ready to negotiate with any willing operator

What are we negotiating over, and what does the CCC require these operators to do to get a license? What does "willing" actually mean? It's not clear, because if they want to set up a network and Cambridge wants them to set up a network, there's nothing to negotiate over. Yes, there are some costs involved in digging up the street, but if they work in other cities, they should work in Cambridge. AFAIK, the details of the Comcast plan are shamefully non-public (at least, I've never seen them), but I think the obvious conclusion is that the council is making unreasonable demands on the ISPs, counter to their citizen's best interests.

This they're-just-not-interested line the CCC is selling simply makes no sense. And until the council is willing to share what their actual demands are and the details of their deal with Comcast, I'll continue to assume the worst.

<comment><USER5> > otherwise why would they have approached the council in the first place?

I know nothing about Cambridge whatsoever, but the quote says council approached operators, not the other way around.

<comment><USER3> You're right, I misread that. Nevertheless, the idea that ISPs are just not interested in Cambridge is prima facie absurd.

</comment></comment></comment></comment></comment><comment><USER6> Well, happy birthday!</comment>


Ask HN: Your Opinion on Labor Unions for Software Developers - <AUTHOR> I'm curious why there isn't any notable amount of interest, discussion, etc, around a labor union for software developers.
I suspect it's somewhat driven by the general approval of a meritocracy...and a similar dislike for tenure driving compensation.
However, if I compare to other highly skilled workforces, like airline pilots...it seems we're missing out on some opportunity.  It's fairly easy to find examples where their unions clearly improved working conditions, treatment during layoffs, salaries, work rules, retirement, and so forth. <comment><USER2> I think if you look into the airline pilots union you will see that the results are _sub optimal_.

Pros: The pilots have managed to capture most of the airline profit.

Cons:

(a) The arrangement accrues most of the value captured to a relatively few pilots. Incoming pilots are payed horrible wages.

(b) An experienced captain must start all over at the bottom of a new airline with intern level pay. I think the famous pilot "Scully" worked on the east coast but lived in California instead of taking a job on the west coast. If he had switched jobs he would have had to start all over at the bottom.

(c) Software development may not be a true meritocracy but it does offer the ability to (due to demand) of moving to a new job whenever you want - we just aren't _that_ exploited that it would be worth putting up with a union.

<comment><AUTHOR> >(b) An experienced captain must start all over at the bottom of a new airline with intern level pay.

It's true that you lose seniority, but I wouldn't call it intern level pay. As an example, at one specific airline, a captain at the bottom of the seniority list is $221/block hour, the top out is at 12 years at $251/block hour.

And, that's applicable if you move jobs yourself. Seniority lists are negotiated in cases like airline mergers.

</comment></comment><comment><USER3> Professionalization of software development could also result in better quality:

[https://www.amazon.com/After-Gold-Rush- Profession-](https://www.amazon.com/After-Gold-Rush-Profession-) Engineering/dp/0735608776

Often the most serious greivances I've had about work are not how I am treated, but dangerous decisions made when creating products.</comment>


Your best web 2.0 site design and why? - <AUTHOR>

<comment><USER2> MySpace.com...because it "works."

/goes back to throwing up.

</comment><comment><USER3> Does Google count as Web 2.0?

</comment><comment><USER4> flickr and netvibes... clean and simple makes it fun

</comment><comment><USER5> LinkedIn</comment>


Betalist Review: Is It Worth Paying $129 to List Your Startup? - <AUTHOR> https://www.netcrumb.com/betalist-review/ <comment><USER2> What I don't understand about some of these sites is who is the target consumer? I mean I get that the customers are startups, but who is going to the site looking for random startups? What do they get out of it?

<comment><AUTHOR> I guess it's entrepreneurs of tech startups that want to check what's new or their competition. Appsumo it's making a lot of money by posting life time deals for different software services. What would be their target customer? Same example with Product Hunt, people go there to discover new tech startups.</comment></comment>


Ask HN: Review my Mac App - WindowFlow - <AUTHOR>

http://windowflow.com
It's kind of a keyboard driven application window multi-tool..
It lets you move, resize & tile groups of windows from the keyboard. It also works as an alternative window switcher.
There's a screencast on the site giving a demo. I'd really appreciate any feedback on if it: does it make sense to you and what new features would be most useful? <comment><USER2> This is pretty cool, I've been working on a similar MacRuby app that I use myself. I used to use some AppleScripts for moving windows to a specific position.

The tiling is great, but I would also like to be able to instantly move a single window to a desired position instead of only being able to tile... I'm sure this could be done with a similar interface that tiling has, only available with one selection though. I also really like the dual monitor support.

One thing I think would help would be able to show the keyboard shortcut panel when WindowFlow is activated but hide it when it's gone. Right now it seems that you can either have it showing all the time or not at all, so you have to manually toggle it on and off when WindowFlow is active to see your options.

Also, I believe that "option" should be used instead of "alt" on Macs. I know the key says alt as well, but option is more prominent and it's the standard in the Apple world.

<http://en.wikipedia.org/wiki/Option_key>

Hope this helps, I'll use it for a while and see if I can get used to it. The selection interface does seem a bit awkward at first for me.

I was thinking you could do something with selection of the first 9 applications with number keys, similar to how TextMate does it, but that conflicts with the shortcuts for tiling. It's an idea anyway, I don't know if you could figure out a way to make that kind of thing work...

<comment><AUTHOR> Great feedback, thank you!

Yes being able to get one window to jump to a particular position would be really handy. There's a shortcut to center a window on screen, I'll add ones for the edges.

</comment></comment><comment><AUTHOR> A direct link: <http://windowflow.com></comment>


A Software Developer's Guide to Dealing with Coworkers (2017) - <AUTHOR> https://simpleprogrammer.com/dealing-with-coworkers/ <comment><USER2> I got accosted by a full page modal to sign up for emails.

No thanks.

Then I realised as I was reading that every paragraph was on average two sentences long.

It seems like this is done on purpose to drive a more conversational style of writing. Too bad it interrupts my flow of reading.

In the end I couldn't finish the article.

It read like a sales pitch.</comment>


New surveillance tech means you'll never be anonymous again - <AUTHOR> https://www.wired.co.uk/article/surveillance-technology-biometrics <comment><AUTHOR> The focus of the article is (as the title states) heavily on the surveillance implications, but most of what they discuss also represents additional forms of potential biometric authentication and are interesting in that respect too (and worth thinking about for people who deride biometrics as a authentication factor, the technology is still in its infancy). Most parts of a person contain significant individual randomness vs the general population when measured at sufficient resolution. The article discusses identifying butts for example, which no doubt provoked some jokes but could be genuinely pretty darn useful in a lot of vehicle anti-theft/security setups. After all, the natural design for these is most commonly for the driver to, well, sit down and then go. So they've got ass-in-seat naturally by definition anyway. Having a butt scanner embedded in the driver seat would be transparent, hard to avoid, and represent a new challenge for an attacker to take.

</comment><comment><USER2> > we need to ask ourselves whether the future society we want to live in is > one which constantly watches its citizens – or, more likely, one in which > citizens are never totally sure when, how and by whom they're being watched.

First, digital behavior is already being 24/7 surveiled. Authorities and corporations only need to extend this to when there is no digital device available with the subject.

But the real danger is that if nobody knows for sure when, how and by whom, then everyone will be forced to assume that it's every time, by every means and by everyone.

And in top of that there is the problem of never being able to truly be forgotten (soft delete). So you lose the motivation to commit mistakes, engage in theoric or philosophical conversations, criticise ahd inovate unless you're going the same direction of status quo. Which only accelerates the process.</comment>


Red Cabbage as pH Indicator - <AUTHOR> https://en.wikipedia.org/wiki/Red_cabbage#pH_indicator <comment><USER2> Science kits for kids sometimes use cabbage powder for pH tests, yes.</comment>


The Future of RethinkDB - <AUTHOR> https://changelog.com/podcast/266 <comment><USER2> I'm interested in the backchannel and business that happens when a company that raises multiple millions of dollars shuts down. Do the investors take over? Do the founders have to pay back investors? Is there any liability personally by the founders to investors? This is something that is never really discussed, probably because it gets messy with lawyers.

EDIT: Just heard Mike say that CNCF acquired the ip and assets of RethinkDB for $20k? That's can't be right? Tiny startups that generate $1k a month in recurring revenue sell for more than $20K. RethinkDB raised over $12M right? What am I missing?

<comment><USER3> The transaction was more of a donation. Companies that get bought are because the technology is strategically important or it is profitable (either business model scales up, or business functions overlap and you can reduce expenses). I'd guess that no companies with enough money to pay sufficiently more than $20K though thought either of those were the case?

<comment><USER2> > I'd guess that no companies with enough money to pay sufficiently more than > $20K though thought either of those were the case?

It seems like an official hosted RethinkDB that included enterprise support could generate pretty nice MRR revenue and take business from Compose.io (IBM). Shoot, wish I'd known, $20K for the ip and assets was a steal. Probably would have been exponentially more to a buyer who wanted to turn it commercial though.

<comment><USER3> I don't know. Databases are a hard business (see Riak, FoundationDB). Costs money to add features and fix bugs (and really hard to find qualified folks that can do that) as well as hosting costs if you offer a service. We'll see what happens with some other entrants. I would read [http://www.defmacro.org/2017/01/18/why-rethinkdb- failed.html](http://www.defmacro.org/2017/01/18/why-rethinkdb-failed.html) regarding DBaaS, too.

<comment><USER2> I've read it. Completely agree about RethinkDB specifically, who raised VC capital on the order of $12M. A cloud hosted solution is a very tough business, with thin margins when you have dozens of employees, $15-$25k a month bay area rent, and very high overhead. The numbers don't add up and not the return investors are looking for.

Though, if you're bootstrapping with your own capital and grow it to something like $10K or $20K a month in MRR, that's a win. I'm all about bootstrapping SaaS companies and growing recurring revenue.

</comment></comment></comment></comment></comment><comment><USER4> I really enjoy RethinkDB. Partly, that's cause it's the first time I've really dug into a nosql database, and I'm loving the freedom of it... Being able to dump stuff straight from a websockets feed straight into the database is awesome! Also, I like the web interface. It's simple and shows me what I want to see with regard to performance and storage.

I haven't really gotten much into doing fancy queries or transforms or streams.

If someone could make a tool that let you use RethinkDB as a (more or less) direct back end for pandas... That would be killer

<comment><USER5> I do a lot of work with RethinkDB + Pandas. We should talk.

<comment><USER6> I use RDB heavily with some Pandas hanging off the side because we haven't integrated them well but looking to improve that. You can get in touch with me if you'd like - I use this handle pretty much everywhere (except reddit ;) ).

</comment></comment></comment><comment><USER7> Is there any update on horizon.io?

it's github hasn't received any update in a very long while

<comment><USER8> I'm not sure if the pun was intended, but if not, it would've made an excellent joke.

<comment><USER9> It's almost hard not to make that joke, horizon.io just lends itself to that so readily.

</comment></comment></comment><comment><USER10> What is the primary use case for rethinkdb (vs other databases) ?

<comment><USER11> We use it here (ZeroTier).

Pros:

\- Very easy and robust clustering (Raft-based, automatic fail-over). This is huge for us.

\- Streaming change feeds. This one is also huge. Makes any kind of real-time, reactive, or event driven programming very easy and IMHO is something that should exist in every database.

\- It's kind of half SQL. It's a NoSQL document store but encourages a relational design and supports many relational queries.

\- Rational and pretty easy to understand query language. It's much cleaner than Mongo.

\- Easy to deploy and configure.

\- It passed the Jepsen tests before Mongo did and overall has a solid history of not losing data.

Cons:

\- It's a CPU hog, at least when compared with PostgreSQL.

\- It's also an I/O hog, though we sponsored some improvements that are getting merged in the next version that will reduce this and also make table commit a configurable parameter. You'll be able to have fully and partially (long flush delay) in-memory tables for highly ephemeral data.

<comment><USER12> How do you handle the lack of transactions / atomic updates affecting more than one document?

<comment><USER11> Our data model generally doesn't require this. We're actually okay with less guarantees than RethinkDB provides. AFIAK NoSQL stores in general are a bad choice if you need this. You should use a SQL database.

<comment><USER13> To be clear, nosql vs sql doesnt mean much - use the right type of database for the scenario: relational, document, graph, key/value, etc.

They all have various support for transactions with relational usually the most comprehensive.

</comment></comment></comment></comment></comment><comment><USER14> Could someone with the time to listen please provide a summary?

<comment><USER15> Listened to it last week -- The gist is that they've found a new home with the CNCF & The Linux Foundation, which bought the IP so that they could continue working on it publicly. Besides the database (which was always open source) this is especially important for parts of RethinkDB that were meant for "enterprise-only", which the company was working on internally before they shutdown. All and all the community support sounds strong, and after listening I decided to take another look at Rethink for my next project :)

<comment><USER16> Small edit: CNCF funded the transaction (to free the IP by relicensing under Apache-2.0) but the project is hosted by CNCF's parent, The Linux Foundation.

Disclosure: I'm executive director of CNCF and did the transaction. And, in case you're wondering, I'm thrilled that the community of people able to take advantage of the code is growing.

<comment><USER17> Dude, really thank you for your hard work on this. Out of curiosity, how did you pull it off?

</comment></comment></comment></comment><comment><USER18> From the transcript, in case anyone was confused:

s/bizzare/bazzar/g

<comment><USER19> Thanks for pointing that out! Our transcriber usually does a great job, but he doesn't get 'em all right.

The awesome thing is that our transcripts are open source and somebody must've read your comment, because I just merged a PR fixing this.

[https://github.com/thechangelog/transcripts/pull/13](https://github.com/thechangelog/transcripts/pull/13)

Our site auto-updates the transcripts after a merge, so your comment is now outdated. :)

<comment><USER20> That was me, and I've read the transcript. :)

</comment></comment></comment><comment><USER21> Thats a lot of text...

Also [https://xkcd.com/927/](https://xkcd.com/927/)

<comment><USER22> I don't think RethinkDB ever intended to unify and replace all existing databases.</comment></comment>