The Blockchain Application Stack - <AUTHOR> http://joel.mn/post/103546215249/the-blockchain-application-stack <comment><USER2> There is tremendous value in distributed ledger, but also tremendous empty hype at the moment. As a rule of thumb, people who tout distributed ledger based solutions ought to ask themselves the following questions:

\- Can this be replaced by a centralized database?

\- If not why?

\- If security / trust is a factor, what is the exact threat model?

<comment><USER3> I think at least on the first on you are asking the wrong question.

The point is not whether it can be replaced by a centralized server the point is whether it's more powerful open than closed.

Personally i find that any system where everyone can become the the validator will always be better in the bigger picture than if they can't.

<comment><USER2> That depends on your threat model, that depends on what you're trying to achieve. There are very large engineering costs to using this type of solution, and in many cases, the benefits are much lesser.

<comment><USER3> Sure but there are many many cases where the cost is much less.

<comment><USER2> There are, but I contend that most of what is being hyped makes no sense. What are the applications that can truly benefit from this model according to you?

<comment><USER3> See [https://news.ycombinator.com/item?id=8659549](https://news.ycombinator.com/item?id=8659549)

Also I think too many are focusing too much on the current state of Bitcoin instead of thinking about the potential.

The crypto-protocol is a product of 20years of research just the last 2 years alone we have seen a host of really intersting ways to improve it and make it less power-consuming.

Sidechains, Stellar and so on we have only just begun to scratch the surface and so I see no reason to be so negative around people trying to think about it conceptually.

But each to their own.

<comment><USER2> > Digital Pokemón Cards. Basically the ability to create digital collectors > items.

Benefits from being distributed, but can use a simple, trusted timestamping service given the low stakes.

> E-books that could gain value. You could sell ebooks at a premium and allow > people to re-sell them. Because the history of their ownership is recorded > you could even see them gaining value if they had been owned by a celebrity.

Celebrities are, by definition, not anonymous, double signing is not a problem. Doesn't need a public ledger.

> Private but public healthcare records for research and usage. Store the > health-records publicly as personas but allow individuals people to link it > with their identity. This would help with research in completely new ways.

That's a distributed database with signed edits. Since it doesn't require to maintain a mutable singleton, it doesn't need a ledger at all.

> Voting made public but anonymous Make it impossible to fake voting results > by making the results available for everyone.

Potentially a good use of a decentralized ledger.

> Artificial Intelligence Using the protocol to create automated consensus > models.

Also potentially a good idea. Those two ideas seem to be related to this proposal, [http://tezos.com](http://tezos.com)

> Companies without owners Build a company with a political purpose without > any owner.

Potentially a good idea.

<comment><USER3> Don't you think it's fair to say that there are enough potential ideas there that are ledger based?

We can always discuss the specifics all of these can be centralized but they benefit from being decentralized.

<comment><USER2> Centralized vs decentralized is not a box to check, there are major costs associated with it.

Imagine for instance someone suggesting that a supermarket offers coupons on a distributed ledger. Sounds like a good idea? No, it's dumb. It's dumb because you trust the supermarket to honor the coupon anyway... there's no credible threat model here.

OK so we've figured our supermarket coupon system can be run on a centralized database. Well, you suggest, sure we can, but why not just have it decentralized if we can?

Because it's expensive. It's expensive in terms of engineering to interface with the blockchain, it's expensive to wait for blockchain confirmations, it's expensive to rely on the non-malevolence of a few mining pools. And did I mention there is about no benefit?

However, this is not the most offending use of blockchain technology. You know what, maybe that supermarket gets to federate their coupons to other stores and you can start to see an engineering case. And maybe you're running this in Argentina and there is a credible threat that the government might want to meddle in you coupon scheme, maybe for price control. OK, then maybe you have a case. No, the worse use of blockchain technology is when there is no need for a global mutable singleton.

The whole idea of a cryptocurrency is that you need to have an irreversible consensus. This is the crux of the double spending problem, you need to dissipate heat to be irreversible (yes actual heat). This heat could come from "overwriting" your key, but that's hard to prove, so instead Bitcoin uses the heat from the ASIC. I'm simplifying a bit, but this can be made rigorous.

However, I've heard many proposals where there is zero need to maintain such a consensus. You mentioned medical records, that's one. People have been talking about running webforums or websites on top of a distributed ledger. Most of those proposals are braindead.

<comment><USER3> That really depends on what you see the technology solving.

For instance it can solve the problem of very slow moving governments and allow people to build solutions that might be necessary for the survival of that society then thats actually quite useful to be able to build your own rules that even if they try can' be shut down by a central unit.

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER3> For those asking about what kind of applications could be created on top of this here are a couple of ideas.

 _Digital Pokemón Cards._ Basically the ability to create digital collectors items.

 _E-books that could gain value._ You could sell ebooks at a premium and allow people to re-sell them. Because the history of their ownership is recorded you could even see them gaining value if they had been owned by a celebrity.

 _Private but public healthcare records for research and usage._ Store the health-records publicly as personas but allow individuals people to link it with their identity. This would help with research in completely new ways.

 _Voting made public but anonymous_ Make it impossible to fake voting results by making the results available for everyone.

 _Artificial Intelligence_ Using the protocol to create automated consensus models.

 _Companies without owners_ Build a company with a political purpose without any owner.

<comment><USER4> You should check out deckbound.com

<comment><USER3> thanks looks interesting.

</comment></comment></comment><comment><USER5> I'm curious to hear more concrete examples of where companies can actually sit (and be profitable) in these new layers. I understand the basics of the blockchain, and always find myself nodding my head in agreement while reading these types of articles, but by the end of the article it seems like it just washed over me and I don't have anything concrete to hold onto.

<comment><USER4> I'll try to drill down to specifics in the series of posts that will follow this, but I wanted to set the general stage first.

To answer your question what's unsettling about this (and not in a bad way) that since so much of this stack is commoditized it becomes very hard to extract value where traditional software business do (20-50% cut rates, etc.) so it is much harder to be profitable, but at the same time it's much easier to bootstrap an application when you have access to an open pool of data.

I think it's an interesting dynamic that, if this turns out to be true, will really change the way software businesses work at the application layer. But I'm 2-3 posts away from doing a deep dive into that part of the stack – there's some things I'd like to go over first.

<comment><AUTHOR> Given that value won't be created in the same way as traditional business do now, what plausible business models do you foresee for software companies operating in this landscape?

</comment></comment></comment><comment><USER6> All you get from the Bitcoin blockchain is the ability to store some public data that's hard for anybody to alter once the data has settled. That's useful for a few special problems, but not widely useful.

The cost of maintaining that blockchain is insanely high - all those giant "mining" operations. Large numbers of machines have to have a copy of the blockchain and track all updates to keep everybody honest. It takes about half an hour before a data item can be considered solidly committed. Even for Bitcoin itself, this is is an operational headache.

If all you need is a certified timestamp on something, several European certificate authorities run free trusted timestamping services. You send in a secure hash of something, they add a timestamp, sign that, and send back a reply.

<comment><USER7> "All you get" is a distributed & anonymous consensus algorithm that's resilient to malicious actors.

 _That_ is the value. If you don't need these properties, sure, you don't need blockchain.

As for the maintenance cost: Proof-of-Stake is making interesting progress. There are initial ideas around not having an entire copy of the blockchain.

I'm not aware of commit-time reduction work, but would welcome pointers. (Either way, you'll always have a commit-time issue in a distributed system. You might reduce it somewhat, but it won't go away.)

<comment><USER8> Tendermint has the strongest guarantees against double-spend attacks.

[http://tendermint.com/docs/tendermint.pdf](http://tendermint.com/docs/tendermint.pdf)

</comment></comment></comment><comment><USER8> This inspired a post here, [http://tendermint.com/posts/sidechains-without- pegging/](http://tendermint.com/posts/sidechains-without-pegging/)

> Sidechains is more than one-way or two-way pegging, and beyond Bitcoin > Maximalism.

</comment><comment><USER9> " _The_ Blockchain"? Let me guess, this guy holds bitcoins.

<comment><USER4> Just a few for coding experiments, only a few dollars' worth.

<comment><USER9> Sorry, just used to the Bitcoin community, who tend to act like the blockchain they have speculated on is the only one that has ever existed. What are your reasons for bitcoin maximalism?

<comment><USER4> I don't like that term but I'll bite.

Bitcoin's liquidity and network effects, in a nutshell. I don't think a competitor will be able to match Bitcoin on those fronts. And it's not just about the developer and technology community, it's about the media, governments, companies, investors, regulators, financial institutions and even regular people who are getting used to the name Bitcoin.

But, honestly, it doesn't matter. This stack is blockchain-independent. Whatever blockchain or currency ends up succeeding in the long run doesn't take away from the fundamentals of this stack: decentralization of data and processes, cost reduction, and consumer power.

I focus on the Bitcoin blockchain because that's what the market has chosen to build on top of because there are no better alternatives yet. We'll see what happens if and when they come (e.g. ethereum), but I worry that it'll be too late by then and the market won't take it.

</comment></comment></comment></comment><comment><USER10>
        unfortunately time coinstraints prevented us from doing a deep dive

Was the typo intentional?</comment>


Ask HN: How to disagree politely and point out errors? - <AUTHOR> I have realised that I tend to disagree with people a lot and it doesn't go down well with them. I start it off as a discussion, but many take offence. Learning is something I immensely enjoy and assume many do too, but this isn't always true. Many outrightly ignorant claims make me furious, and I get into heated arguments. Sometimes I learn something, but many times people don't want to discuss and I end up being a jerk in their eyes. Am I wasting time doing this or is it realistic to hope to learn something this way? I just want to know what HN does. <comment><USER2> It depends. Are you dealing with a "rational" actor? Are you dealing in the objective or the subjective?

If you are dealing with someone nominally rational on a subject of some objectivity, the question is really how do you interpret the science and how it that enforced or detracted from by your lived experience. That doesn't invalidate the science, but it helps with perspective.

If you are dealing with an irrational actor but an objective issue, you can throw the science in their face but that is generally not a good way to approach it. Humans respond defensively as a reflex. If someone knew the "one truth" to the world, I would reflexively and cynically respond that they probably don't, and counter-argue. I might investigate the alternatives though. I think the goal here is just convince them to do more seeking. And if they are unwilling to do that _and_ to change to the objective side of things, they aren't worth the time (period).

If you are dealing in the subjective, the same things tend to apply but be more careful. You are dealing in the realm of lived experience, espoused values and old wisdom. Old wisdom tends to be better than new wisdom, unless the nature of the problem is new, and lived experience tends to always be more compelling to you than to others around you.

Mostly, you are wasting time trying to change minds. Try to point people in the direction where they can learn for themselves, no one wants to be taught, they want to be shown, and sometimes they are more open if you validate their perspective first (not sarcastically, truly validate it, and then proceed to attack the central argument).</comment>


Recursion in a Few Lines - <AUTHOR> http://lambdaway.free.fr/lambdaspeech/?view=BOOK_ONE <comment><AUTHOR> I need your (kind) appreciations to improve my work. Thanks.</comment>


Ask HN: Any subscription-based service is easy to join and easy to quit? - <AUTHOR> Seems most subscription based service adds all kinds of friction to prevent you from canceling the subscription...<p>This applies to both online and offline (e.g. Gym) businesses ... <comment><USER2> Reddit Gold is as easy as can be. Twitch.tv subscriptions are 1-click to subscribe and unsubscribe. My svbtle site is super easy to stop paying on if I wanted too. Even my PO Box is super easy to stop recurring payment on.

Don't know what services you use, but in my experience respectable companies make it pretty easy.</comment>


Steering Behaviors for Autonomous Characters (1999) - <AUTHOR> http://www.red3d.com/cwr/steer/gdc99/ <comment><USER2> Oh, "boids", repelled by obstacle force fields. That works great in some situations, like crowd simulations. We discovered when we tried to use it for the 2005 DARPA Grand Challenge that it won't work when you have a turning radius limitation and narrow roads.</comment>


The Ultimate Twitter Search Tool? - <AUTHOR> http://www.twitterrati.com/2008/12/25/the-ultimate-twitter-search-tool/ <comment><USER2> <http://tweetgrid.com/> is the search engine. It's pretty cool. Chad is doing a bunch of other things with Twitter. Check out his homepage <http://jazzychad.net/>

He's really active on the Twitter API Google group, I'm glad to see his Twitter projects are getting some love.

</comment><comment><USER3> Summize/Twitter Search supports boolean operations, which I prefer:

        something OR "another thing" OR "something else"</comment>


Report: Dell layoffs this week – 15,000 to be hit - <AUTHOR> http://www.zdnet.com/dell-layoffs-this-week-15000-to-be-hit-report-7000025879/? <comment><USER2> This is not surprising. Michael Dell spent billions to take the company private because he believed the company was undervalued and under- performing[0], and that he knew how to save it, not because he was content with leaving it the way it was.

That process necessarily involves personnel changes - if anything, I'm surprised we didn't see these sooner.

The real question will be _who_ they're cutting (and more importantly, who they'll be replaced with, or if those positions will be replaced at all).

[0] The other reason public companies go private is to liquidate, but that's clearly not his goal.

<comment><USER3> It'll be interesting to see how development is affected. Dell has had a reputation of being the place to work if you wanted a high salary with minimal responsibilities here in Austin. I've heard the politics are brutal, though.

<comment><USER4> That sounds so different from their office in Porto Alegre, Brazil. It's a sweatshop there. I know a number of people who work/have worked there and they all say it's awful.

</comment></comment></comment><comment><USER5> They have 108.8k employees [1], so this represents 13.8% of the company.

[1] [http://en.wikipedia.org/wiki/Dell](http://en.wikipedia.org/wiki/Dell)

<comment><USER6> Interesting. That's roughly a computer a day per year per employee. Assuming $40k / year per employee, that's $111 bucks per computer of employee cost. Hirer than I thought.

<comment><USER7> They sell more than computers though. Monitors, printers, servers, storage, support, etc etc.

</comment></comment></comment><comment><USER8> I feel bad for anyone who didn't see the writing on the wall when Dell was initially acquired. Large-scale layoffs are a key tool for private equity firms when they take a company private. Indeed, if Dell didn't have a lot of fat to trim, it would have been a much less attractive takeover target in the first place.

</comment><comment><USER9> How are they not triggering the WARN act? 15,000 is a lot more than the 100 that it requires.

<comment><USER10> _The Worker Adjustment and Retraining Notification Act (WARN) protects workers, their families, and communities by requiring most employers with 100 or more employees to provide notification 60 calendar days in advance of plant closings and mass layoffs._ [1]

I assume Dell is dealing with the _WARN act_ 's 60 days notification by including 60 days paid leave in the severance package. The article says that " _the severance package includes two months ' pay plus an extra week for each year in Dell's employ, a bonus at 75 percent, health insurance for 18 months in the U.S. and some outplacement services at least stateside._"

[1] [http://www.dol.gov/compliance/laws/comp- warn.htm](http://www.dol.gov/compliance/laws/comp-warn.htm)

<comment><USER11> That's a crazy amount of COBRA/health insurance severance. Not saying its a bad thing, you just don't see it that often.

<comment><USER12> As an ex-employee, you're entitled to the 18 months by law. The difference here is that Dell is apparently paying for it, not the employee (although maybe that's what you were referring to as the "crazy" part).

<comment><USER11> > although maybe that's what you were referring to as the "crazy" part

Yes. To be frank, in my mind, that offsets a lot of ill will toward the layoffs. Sure, you're getting let go. But you'll have almost 2 years of health insurance paid for, and unemployment for at least a year (plus severance).

Not that bad of a deal.

<comment><USER13> Yeah, that's a whole lot of _cash_ to be paying out, especially times 15,000! Even over two years, its a LOT.

Has to be at least $100 million I'd think, possibly even just in the insurance cost alone, not to mention the direct severance compensation too.

Very respectful & respectable package IMO, probably why the news was released on a Monday, eh? ;-)

<comment><USER11> Luckily for Dell, the health insurance is going to be a straight business deduction.

</comment></comment></comment></comment></comment></comment></comment><comment><USER14> When operating at thin margins, if those margins disappear the only way to stay afloat is to cut costs. The "easiest" way to cut costs quickly is to reduce your labor force. It is much harder to cut operational costs like buildings and infrastructure without incurring extra cost or taking a big loss.

This is one reason why operating a high margin, low cost business is probably better for both the owners and the employees.

</comment><comment><USER15> It's curious that the PC model of selling the customers relatively modular systems is rapidly falling by the wayside in favour of highly integrated systems, which at their logical extremes are completely unmodifiable. We've crossed the point at which system integration outside of the SoC is going to get less valuable very fast.

PCs are clearly headed this way too, but it means economies of scale for particular configurations are going to be much harder to come by.

</comment><comment><USER16> So that's why nobody at Dell responded to my application (already working somewhere else, don't worry).

</comment><comment><USER17> Wonder how hard this is going to hit the Austin/Round Rock area this time (again).

</comment><comment><USER18> Dude, you're getting a pink slip!

<comment><USER19> Your comment also reveals how the only Dell-related ad people can remember is 10+ years old.

<comment><USER20> The company hasn't changed in ten years. Their notebooks today look virtually the same as those from ten years ago. Maybe a little thinner, plus they come in different colors, but that's about it.

<comment><USER21> You can say the same about Apple. Dell still the best workstations, though, unlike HP with their stupid redesigns.

<comment><USER20> Apple's Mac Pro looks nothing like any computer ever made before, and their new MacBook Retina machines are radically different from their 2004 Aluminum Powerbook models.

I kind of like HP's redesigns, it shows they're trying. The Envy isn't bad for a MacBook inspired knock-off.

</comment></comment></comment></comment></comment><comment><USER22> We'll see many more layoffs like this in the coming weeks / months as the Fed tapers off. This is macro related.

<comment><USER23> Can you possibly explain a little more? From my research [1] the fed tapering off looks good for business as stocks skyrocketed according to the article [1]. Personally I think it is good the Fed is tapering off and starting a slow transition (note: I have libertarian views hence less gov't involvement the better). Obviously, I am no expert, maybe someone can explain why it's bad other than the market might not being ready?

[1] - [http://www.cnbc.com/id/101282912](http://www.cnbc.com/id/101282912)

<comment><USER22> Fed tapering means there's less liquidity in the markets. That's because they're buying up less risky assets off the financial institutions. Less money in the market means less "free" cash available to be loaned up for risky investments. I wrote a little about this in this submission: [https://news.ycombinator.com/item?id=7172139](https://news.ycombinator.com/item?id=7172139)

Of course I can't predict what will happen but it's very clear that less money always means less money. A lot of businesses rely on bank loans to make ends meet with regards to payroll. This might not apply to Dell but it applies to a lot of small business owners who need the extra help until they get paid by their clients and then pay off the short term loan. Stricter payroll loan policies (when money is scarce = bank reaching low levels of liquidity) puts businesses in tough situations leading to sudden layoffs.

The Fed's goal is to try and regain control of the system (they lost control last summer). So by tapering they're shaking the tree. Just like you'd put an electrical signal through a black box and study the output in an attempt to understand how it works, the Fed is gradually cutting its $85bn per month supply of "cash."

That's what the Fed (Yellen) is doing right now. I'm sure they'll react if things degenerate too much.

FYI, it's a carnage in the financial markets right now. Dow was down several hundred points in Jan. Several hundred points just today.

<comment><USER7> ... Except the Fed is mainly buying Treasury debt. It actually encouraged loaning out for "risky" investment by pushing down interest rates. That's why there's the fear in emerging markets as the program winds up.</comment></comment></comment></comment>


Regular Expression Matching Can Be Simple And Fast - <AUTHOR> http://swtch.com/~rsc/regexp/regexp1.html <comment><USER2> Textbook regex algorithms assume that you're trying to determine whether a string matches an expression using a standard set of operators. Perl regular expressions have to match text to subexpressions, rather than just return a yes/no answer, and have a greatly expanded set of operators, some of which are completely incompatible with the usual NFA and DFA algorithms. It even lets you drop arbitrary perl code into the middle of a regex. You can easily write a perl regex that is NP-complete to match. You can't do that with the simplified regex language that textbooks talk about.

<comment><USER3> "some of which are completely incompatible with the usual NFA and DFA algorithms" - It would be nice if you pointed to some article/resource giving more info on this.

<comment><USER4> Well here's a starter for you. Using enhanced regex syntax you can match a language containing strings of prime length. On the other hand (using the pumping lemma[1]) you can prove that that set is not regular, hence not detectable by a standard regex.

[1] [http://books.google.com/books?id=MDQ_K7-z2AMC&pg=PA47...](http://books.google.com/books?id=MDQ_K7-z2AMC&pg=PA47&lpg=PA47&dq=finite+automaton+prime&source=bl&ots=0wWTv5AeBd&sig=6sOwOf6PNdQmcvI6QhWVMKLvKKA&hl=en&sa=X&oi=book_result&resnum=3&ct=result)

<comment><USER5> Sipser's book is great for understanding this stuff, IMHO: [http://books.google.com/books?id=eRYFAAAACAAJ&dq=sipser+...](http://books.google.com/books?id=eRYFAAAACAAJ&dq=sipser+theory&ei=SvqKSfnBHZb0ygS22KG6BQ)

</comment></comment></comment></comment><comment><USER6> This reminds me of a very interesting article on the same vein from the great (now sadly defunct) Ridiculous Fish

The Treacherous Optimization [http://ridiculousfish.com/blog/archives/2006/05/30/old- age-a...](http://ridiculousfish.com/blog/archives/2006/05/30/old-age-and- treachery/)

<comment><AUTHOR> That's a good article. Ridiculous Fish is awesome. You should submit it!

</comment></comment><comment><USER7> So why don't Perl, Ruby etc. use Thompson NFA?

<comment><USER8> Same question here. I didn't realize that they didn't. regular expression NFA and DFA algorithms are in _every_ compiler book out there. I find it hard to believe that guido et al. didn't know about these algorithms.

<comment><USER9> Yeah, jimrandomh's comment basically explains it. Perl regexp's have features that can't be implemented by a DFA, like backreferences and arbitrary code evaluation. (I believe you _can_ implement capturing subgroups, you'd just need to annotate the states with a marker for the current position in the string.) Those features are used often enough that you can't just leave them out.

I see no reason why popular languages couldn't implement _both_ algorithms, though, and then select the backtracking one only if the regexp contains backreferences or expressions. It's easy enough to tell if a regexp uses these features, just checking for their existence when the regexp is compiled. Then you could use the fast algorithm when possible and the featureful one when not.

<comment><USER8> Nope. Backref and friends can be implemented on top of DFAs. Grep offers an example of such an implementation.

</comment></comment></comment></comment><comment><USER10> I'm curious why they don't do some sort of cost-estimation when doing the regex compile. Oftentimes you use a regex only a few times in the life of the application, and it'd be nice if maybe it would build the regex automaton with some time-budget cap (say, N states created) and fallback to PCRE until its fully built.

(Backseat nitpicker here. And just thinking about it seems deliciously hairy.)</comment>


Obama Unveils Climate Change Strategy: End of Line for U.S. Coal Power? - <AUTHOR> http://news.nationalgeographic.com/news/energy/2013/06/130625-obama-unveils-climate-change-strategy/ <comment><USER2> While I am glad to see it, it looks pretty weak given the scale of the problem and might even backfire.

It is likely to increase the use of natural gas and thus fracking and methane emissions. The methane is troublesome because it could produce a fast big spike just as the CO from the last two centuries really has an impact.

[http://science.howstuffworks.com/environmental/energy/emissi...](http://science.howstuffworks.com/environmental/energy/emissions- natural-gas.htm)</comment>


Clear CEO answers biometric security questions - <AUTHOR> https://www.recode.net/2017/12/28/16826070/clear-ceo-caryn-seidman-becker-answers-biometric-security-fingerprint-iris-scan-too-embarrassed <comment><AUTHOR> I don't know whether to be impressed or freaked out by the capture of so much biometric data. On the one hand it would be convenient to not have to carry these little cards with me all the time to prove who I am and how I would like to pay for things. The only reason I take my cell phone to the gym is because my membership ID is too long to remember and its easier to scan the barcode at the front desk.

On the other hand giving your personal, persistent data to a 3rd party, which promises not to sell it or give it to the government, feels creepy. I know it's a trope but it really does remind me Minority Report and makes me wonder what type of Pandora's Box this type of thing would open.</comment>