Jonathan Blow criticises Linux dev tools - <AUTHOR> http://www.develop-online.net/news/43175/Jonathan-Blow-criticizes-Linux-dev-tools

<comment><USER2> Blogspam of an _HN comment._

OP is <https://news.ycombinator.com/item?id=5124476>

</comment><comment><USER3> I work on game servers that run on both linux and windows. (We deploy to linux but most of our developers work in windows as that is what the client runs on).

If there is a crash or other bug the first question is always "Can we reproduce this on windows servers?".

I spend about 50% of my time using GDB and 50% in Visual Studio for debugging. GDB is just crap compared to Visual Studio has a debugging tool.

<comment><USER4> I had always wondered what market the window debugging was tuned for.. Building by bug fixing in a debugger and then shipping it to someone without a debugger does seem to be the norm both on windows and in the game industry.

I worked for a UNIX vendor and our gdb style commands were ideal for business and government customers and products.

The time spent diagnosing bugs during production is not nearly as important as the ability to diagnose bugs remotely with limited amounts of data collected (and in many cases read and redacted) by a customer running a machine with sensitive data.

For live debugging we really relied on truss and dtrace. There are ports/copies of them in Linux, I don't know how complete..

</comment></comment><comment><USER5> Seems unnecessarily meta to submit stories about comments on HN. Original thread can be found here: <http://news.ycombinator.com/item?id=5124476>

</comment><comment><USER6> Yes, GDB might not be that great for application developers. But GDB is a mighty powerful tool that you can use to debug in various environments.

You can use GDB with a regular user space application or attach it to a dead process with a core file. Or you can plug it to QEMU to debug a bootloader or a kernel image in emulation. Or you can use remote debugging over the network or over the serial port. It's possible to add GDB stubs and run your custom kernel image running on bare metal, debugging via serial connection. You can debug a program running on a microcontroller like Arduino. You can even use it to debug Windows applications remotely from the comfort of your Linux desktop. In my day job and my hacking hobbies I have used all of the ways of using GDB I mentioned in this paragraph.

So yeah, GDB is not a pretty source level debugger like Visual Studio or Eclipse, the versatility comes at a price.

LLVM Project's LLDB debugger may make application debugging less painful in the future.

</comment><comment><USER7> I just seriously don't understand all the GDB hate. It might have a steep learning curve, but I feel _much_ more comfortable and productive in GDB than I ever did in Visual Studio's debugger.

Is it the most amazing debugger ever? Certainly not. But it gets the job done. LLDB looks promising as an alternative, but it's not mature enough yet.

Also, what's with the fetish with IDEs? I only use an IDE when I write Java (since navigating even a "simple" Java codebase is difficult without one), but for anything else, I spend all my time in vim and a terminal, even for large projects.

<comment><USER8> GDB is okay once you get the hang of it, but it's seriously less productive than with proper IDE integration.

How do you make a breakpoint? 'break Filename.cpp:1234' or 'break FullClassName::FullFunctionName'. I have to go to my editor, lookup the file and line number, go to gdb and enter a command. Remove a breakpoint? I always forget how to do that so I need to lookup the manual every time. Urgh. I just want to be able to click on a button next to the line to insert or remove a breakpoint.

The command line interface has its uses, but there should _also_ be excellent editor integration. I don't care about IDEs; integration with Sublime Text is fine. Unfortunately every project that I've come across that tries to implement that is half-baked.

</comment></comment><comment><USER9> Lots of mentions (and warranted criticisms of) GDB for its failings and (especially) nightmarish IDE/GUI integration, no mention of LLDB[0] which aims to fix exactly that (amongst many other things).

[0] <http://lldb.llvm.org/></comment>


UK government bars foreign academics from advising on Brexit - <AUTHOR> https://www.theguardian.com/politics/2016/oct/07/lse-brexit-non-uk-experts-foreign-academics <comment><USER2> Well if anyones being honest this is quite drastic (for example, even a dual citizen cannot participate), but one has to remember that the information these politicians needs to get has to be impartial and have no influence. While I know this is a terrible example because it's not a war, in a time of war would you hire people from the people you're fighting with/negotiating with to give you information?

I've seen tons of my friends argue for and against TTIP, and I just wonder the problems there about foreign influence in a trade deal isn't a problem?

They need academics to provide economic advice but it should be impartial right? Imagine 40 years down the line it comes out as 'hey that guy was actually an automotive lobbyist, but the laws set now'

<comment><USER3> Did you read the article?

It has nothing to do with trying to get unbiased information. They've classified some of the negotiation information, i.e. they think a Danish national is more likely to leak sensitive information to the Danish government than a British national is.

Given the strength of feeling across the EU on these topics, I can't completely blame them.

<comment><USER2> This is my point. I'm pointing it out that its a conflict of interest and entirely justified. Many people do not think so - if you read the other comments in this thread you get an idea.

I'd also advise you to take a look at the community guidelines on making comments on HN: [https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html)

3rd paragraph under 'In Comments'

</comment></comment></comment><comment><USER4> Heads in the sand...

<comment><USER5> I think they'll need to exclude all academics if they want advice on where they can put their heads that is suitable for publication.

</comment></comment><comment><USER6> This is discrimination.

They should bar all academics, not just the foreign ones!

</comment><comment><USER7> Yikes. Time to leave before they start rounding us up.

<comment><USER8> If you qear glasses, get contacts now!

<comment><USER7> Is there some pun here that I'm missing? :D

<comment><USER9> Reference to the Khmer Rouge

[https://redditblog.com/2015/10/14/cambodia-khmer-rouge- murde...](https://redditblog.com/2015/10/14/cambodia-khmer-rouge-murder- eyeglasses-intellectuals/)

<comment><USER7> Thank you. Very clever. I'm stealing it.</comment></comment></comment></comment></comment>


New organic compounds found in Enceladus ice grains - <AUTHOR> https://phys.org/news/2019-10-compounds-enceladus-ice-grains.html <comment><USER2> So cool!!</comment>


Ask HN: Would you like Affirm for credit card? - <AUTHOR> If you could get a credit card where you can pay for your purchases in monthly installments without interest rate for 2 or 3 months but with interest rate for more than that, would you use it? <comment><USER2> In the US, this is a pretty common form of financing for bigger durable goods (furniture, etc) - they call it "N months same as cash" but it's implemented as a credit card with a 0% interest rate for just that purchase for a limited time.

</comment><comment><USER3> Off course, butb only when I can make more by: Tell a friend, referral bonus.</comment>


5 html elements you probably never use but should - <AUTHOR> http://www.seomoz.org/blog/5-html-elements-you-probably-never-use-but-perhaps-should

<comment><USER2> Summary:

<address>, <q>, <optgroup>, <acronym> or <abbr>, <fieldset> and <legend>

</comment><comment><USER3> This article is quite old. You'll find more recent use cases/examples on the current HTML5 editor's draft (<http://dev.w3.org/html5/spec/Overview.html>). In its temporal context the author was right (fieldset/legend/abbr weren't that used) but fortunately times have changed a bit and things aren't as bad as he describes.

<comment><USER4> I must be one of the luck SOBs who learned proper HTML and web development first, having picked up this whole web fad just in the last year (took a long hiatus, my last web app before that was written in 2003.) I have html- generating macros and I use legend, label and abbr within fieldsets throughout my code base (though I usually forget they even exist until I see the generated code.)

</comment></comment><comment><USER5> Hate to be a jerk, but I really don't see what <address> adds over <div class="address">

It is was an actual microformat for addresses, that makes sense, but it's not. It's just a tag that implies that some kind of address (virtual, physical, who knows) is contained within. Who does this actually benefit?

<comment><USER6> <address> doesn't mean what you think it means:

<http://www.w3.org/TR/html401/struct/global.html#edef-ADDRESS>

"The ADDRESS element may be used by authors to supply contact information for a document or a major part of a document such as a form. This element often appears at the beginning or end of a document."

<comment><USER5> Fair enough, but what does that add?

We should use the tag so that some yet-to-be-invented web spider might be able to automatically extract contact info for the pages it crawls?

<comment><USER7> <address> is what people should have been using all along - I remember it was common in academic websites in the early-mid 90s, but it fell out of fashion. Similarly <em> for emphasis, the semantic meaning was lost when people switched to <b> and <i> instead.

</comment></comment></comment></comment><comment><USER8> Good comments were made on a similar list of underused html elements that was submitted some time ago:

<http://news.ycombinator.com/item?id=481067>

</comment><comment><USER9> <q> doesn't seem to work in Firefox 3.0

<comment><USER10> The page just doesn't have the actual styles applied to it. I can verify it works in FF3 when you style it properly; I use it myself all the time.

</comment></comment><comment><USER11> none of it seems to work very well at all in Chrome, or my Firefox 3.0

Seems to be a very redundant article.

</comment><comment><USER12> The only tag I thought was actually useful is <optgroup>, when you have Categories (labels) in your drop-down <select> that you don't want to be selectable.</comment>


Is our usability test library useful/fun/interesting? - <AUTHOR> http://peek.usertesting.com/library <comment><USER2> Usertesting once had a useful service called "peek". Simple website testing without much fuss. Their other services are too complex for my needs. Lately I tried to use peek again and they said a test would arrive soon. It never did. i mailed the support and they replied with a note like "yeah, we don't offer that service anymore". The signup page for peek is still open though. That left a bad taste in my mouth.

Funny, the link they posted here goes exactly to the peek service. When you put in a url, you get a text "it wont be long". Well, last time it took forever. A better user experience would be "you are nr ... in the queue. bookmark this link to check your position later".

<comment><USER3> Disclosure: I work at UserTesting.

Peek is still running, but it is not a service intended for repeat use. It is meant to be a free and easy sample of the primary UserTesting product: videos of people completing tasks on a website or app. I admit this could be more clearly communicated.

I'm happy to answer questions by PM if you'd prefer not to talk to sales or support (I'm a UX researcher).

<comment><USER2>
        it is not a service intended for repeat use

Yet you say on your site "Peek is always free, and you can run 3 Peek tests every month.".

That is exactly what I mean with "leaves a bad taste in my mouth". Advertising a service with false promises. I am happy to pay for webservices, but not if I have been tricked into using them in the first place.

You should be straight about it right on the frontpage. Like "First test is free, additional tests are $X".

<comment><AUTHOR> I believe what was meant by "not intended for repeat use" is that Peek is a very limited product, meant to introduce people to usability testing.

We do allow and even encourage people to test their sites out on Peek up to 3 times each month, but we hope that as their needs grow and they recognize their needs for targeted demographics, custom tests, and many of the other great features we offer they'll consider using our full product.

Sorry for the confusion, we are certainly not trying to deceive anyone.

</comment></comment></comment></comment><comment><USER4> It looks potentially all of useful/fun/interesting, though unfortunately it seems to be experiencing severe video performance problems right now so most of the videos/playlists don't seem to get past the initial intro/trailer for Peek itself.

<comment><AUTHOR> Thanks for checking it out! We had some issues with playlists, but we've got the videos working now. Poor timing :(</comment></comment>


The Controversy of MSG - <AUTHOR> https://en.wikipedia.org/wiki/Glutamate_flavoring#Controversy <comment><USER2> MSG is to me the poster child of most things are OK in moderation. The problem is most people are pretty terrible in practicing moderation and so they're essentially consuming super salt in large quantities which certainly can't be good for you.

MSG can really make certain dishes taste delicious, but that doesn't mean you need to dump tablespoons of the stuff into everything you eat. In Japan, many foods contain MSG; just not enough to be your weekly serving's worth.

</comment><comment><USER3> Harold McGee on MSG: [https://www.youtube.com/watch?v=k1oR0EYaOHY](https://www.youtube.com/watch?v=k1oR0EYaOHY)</comment>


Shareholder Capitalism is Dead - <AUTHOR> http://blogs.hbr.org/hbr/hbreditors/2011/07/shareholder_capitalism_is_dead.html

<comment><USER2> This article, like many articles on this topic, has a significant flaw: "Pay started taking off in the 1980s, at the beginning of the era of shareholder capitalism."

In fact, pay in the US started taking way off in 1986, and more or less stabilized in 1988. Coincidentally, there were major changes to the tax laws in 1986 which encouraged shifting income from corporate balance sheets to individual balance sheets.

(I.e., the CEO gets paid more, but doesn't get a company car.)

[http://www.scottwinship.com/1/post/2011/03/what-would-it- mea...](http://www.scottwinship.com/1/post/2011/03/what-would-it-mean-for- theories-of-us-income-inequality-growth-if-the-us-experience-has-been-similar- to-that-everywhere-else.html)</comment>


Programming with Categories - <AUTHOR> http://brendanfong.com/programmingcats.html <comment><USER2> As someone who respects functional programming (because it removes geniuses from competing in my space) here's a nice video [https://www.youtube.com/watch?v=ADqLBc1vFwI](https://www.youtube.com/watch?v=ADqLBc1vFwI)

What is the beautiful monospace font in the pdf here [http://brendanfong.com/programmingcats_files/cats4progs- DRAF...](http://brendanfong.com/programmingcats_files/cats4progs-DRAFT.pdf)?

<comment><USER3> > here's a nice video > [https://www.youtube.com/watch?v=ADqLBc1vFwI](https://www.youtube.com/watch?v=ADqLBc1vFwI)

OMG. That might just be the funniest god-damned thing I've ever seen in my life. Thanks for sharing that!

On a separate note: does anyone know where this footage is originally from? Some WWII movie, I would guess?

<comment><USER4> [https://en.wikipedia.org/wiki/Downfall_(2004_film)](https://en.wikipedia.org/wiki/Downfall_\(2004_film\))

Probably one of the best "WWII movies" (it's really only about the final days in the bunker) ever.

<comment><USER5> Just seconding that Downfall is brilliant. Totally off-topic now, but also extremely good is Das Boot.

</comment></comment></comment></comment><comment><USER6> When taught in January at MIT, a highlight was something I'd not seen elsewhere: someone called it the "aftermath" (3-pun). After the one-hour traditional-ish lecture (on video), the room was reserved for an additional hour.

When previously taught, people would remain afterwards to ask questions, discuss math, and chat. So this was an iterative-improvement formalization of that.

People would gather in front of the blackboards in fluid discussion clusters. Catalyzed by the three instructors and wizzy others, not all having to stay for the entire hour, but drifting off as discussion died away. They could show material they had pruned from the lecture, for want of time. Or got dropped as they ran over. Alternate presentation approaches they had considered, before selecting another. They could be much more interactive. One commented roughly "If I was tutoring someone, I'd never present the material this way". It was a delightful mix of catching the speaker after a talk to ask questions, a professor's office hours, a math major's lounge, an after-talk social, tutoring, an active-learning inverted classroom, hanging out with neighbors in front of the hallway blackboard, chalk clattering and cellphones clicking to snag key insights... It was very very nifty.

So, the book is nice. And lecture notes. And videos. But... the best part isn't there. Perhaps the next iterative improvement is to capture the aftermath on video, and share that too.

And as we look ahead, planning distance-learning and XR tools... maybe something like this is a vision to aspire too. The insane ratio of expertise to people learning is not something one can plausibly replicate in meatspace. But as conversations in front a virtual blackboard gradually become technically feasible, something like this might pay for the cost of it, with transformative impact.

<comment><USER7> This is the most valuable part of the in person learning experience. Free form discussion and building intellectual context around a subject. I experienced this in a community college environment. This should be encouraged in any learning environment.

<comment><USER8> This is what I sort of dreamed university would be like. But alas it wasn't. Just lectures and students doing the minimum to get through the week and hit the bars.

</comment></comment></comment><comment><USER9> If you're interested in how Category theory and Algebra can inform the design of software, have a look at ZIO Prelude.

[https://github.com/zio/zio-prelude](https://github.com/zio/zio-prelude)

It's a brand new library for Scala that contains reusable mathematical structures. Still based on algebra and category theory, but it expresses them more or less differently than how they've been expressed in Haskell (and similar languages). For example, unlike Haskell (and Scala's own cats and ScalaZ), it doesn't present the "traditional" Functor -> Applicative -> Monad hierarchy. Instead, it presents the mathematical concepts in a more orthogonal and composable way.

One example out of many, you don't have a Monad. You have two distinct structures:

* Covariant functor, with typical map operation `map[A, B](f: A => B): F[A] => F[B]`

* IdentityFlatten which has a flatten operation `flatten[A](ffa: F[F[A]]): F[A]` and an identity element `any: F[Any]`

When combined together (Scala has intersection types), you get something equivalent to the traditional Monad.

The project is in its infancy, so it may still change significantly, though. Look here for more detailed explanation:

[https://www.slideshare.net/jdegoes/refactoring-functional- ty...](https://www.slideshare.net/jdegoes/refactoring-functional-type-classes)

[https://www.youtube.com/watch?v=OwmHgL9F_9Q](https://www.youtube.com/watch?v=OwmHgL9F_9Q)

<comment><USER10> Are there any useful types that have `flatten` but not `map` or `contraMap`?

<comment><USER9> If I understood John's motivation from the video, it's that this enables the Flatten structure to be inspectable, because the innards are not hidden behind an opaque closure (A => F[B]), as is the case in regular Monad.

Btw, this is a problem that the "Selective applicative functor" too aims to alleviate.

You can read more about the inspectability problem (and Selective) at [http://eed3si9n.com/selective-functor-in-sbt](http://eed3si9n.com/selective- functor-in-sbt)

The context there is sbt, which is a build tool, but I'm sure the inspectability plays role in many other areas. Note, how he contrasts "Applicative composition" and "Monadic composition".

</comment></comment></comment><comment><USER11> I've read a lot about Category Theory, and I'm amazed at the abstraction level that lets you compose with different mathematical domains (geometry, topology, arithmetic, sets, ...).

And yet, the current mathematics relies heavily on the ZFC set theory. Why is that ? (Is that assumption even correct ?)

From what I've learned so far, the set theory suffers from Russel's Paradox[0] (does the set of all sets that does not contain itself, contains itself ?). That's what motivated the formalization of Type Theory and the invention of Type Systems in programming languages.

According to wikipedia[1], __some __type theories can serve as an alternative to set theory __as a foundation of mathematics __.

It seems to me that the Category Theory fits the description. So why don't we see a huge "adoption" in math fields ?

Thank you in advance for your clarifications :)

[0] - [https://en.wikipedia.org/wiki/Russell%27s_paradox](https://en.wikipedia.org/wiki/Russell%27s_paradox) [1] - [https://en.wikipedia.org/wiki/Type_theory](https://en.wikipedia.org/wiki/Type_theory)

<comment><USER12> ZFC does not suffer from Russel's paradox, since it doesn't allow a "set of all sets". If it did, the search for new foundations would be much more widespread. New foundations are usually only considered seriously once they can be shown to be relatively consistent with ZFC or the slightly stronger but still uncontreversial TG set theory.

There are people working on categorical foundations, but the main reason for lack of broader popularity or drive is that most mathematicians don't do work that is "foundational" in that sense. For example, if you're an analyst, you generally don't care exactly how your real numbers are built (dedekind cuts, Cauchy sequences, etc.). You only care that they satisfy a certain set of properties, you can define functions between them, and that's about it. Most mathematical reasoning at this level is insensitive to differences in proposed foundations, except "constructive" foundations that don't have the law of excluded middle (that are unpopular since they make many proofs harder and some impossible).

What is very popular in mathematics is using category theory at a high level; basically every field uses its concepts and notation to some degree at this point. New foundations are only really relevant to this program in that they may make automated proof checking easier, which is also not a widespread practice in mathematics.

<comment><USER13> It is not true that "basically every field uses its concepts and notation to some degree at this point." In particular this is false for mainstream combinatorics, PDE, and probability theory, to give a few examples.

In fact, I would suggest that most mathematicians don't care about category theory at all.

<comment><USER14> This all hinges on "mainstream". For example, in combinatorics, combinatorial species are a vast organization of the all-important concept of _generating function_. They were developed by category theorists and are most tidily organized along categorical lines. If you don't think this is close enough to mainstream, I can't dispute that. It's a value judgment.

There is often an undercurrent of category theory within a subject that maybe most people are not privy to. Anything to do with sheaves or cohomology (which I know factors into some approaches to PDEs) are using categorical ideas.

Every generation, it seems, has some contingent of serious mathematicians who consider category theory marginal in their field of interest. But every generation, that contingent grows smaller as more mathematics as practiced is brought into the fold. Maybe they're coming for you next :)

<comment><USER13> Respectfully, I disagree. The question of what's mainstream and valued by the community is empirical and can be answered by looking at what's published in the leading combinatorics journals. And anyone can check those out and see that categories are basically absent. So as a sociological fact, I maintain it's far from the mainstream.

Whether combinatorialists _ought_ to elevate certain work is of course of a question of value, but it's also a different question.

Also, in no way are sheaves or (co)homology essentially category-theoretic ideas. It's possible to develop and use these ideas without mentioning categories at all (and e.g. Hatcher's introductory textbook does just this, although he mentions in an appendix the categorical perspective later). In general I think it's good to remember that homological algebra and category theory are not the same subject. Sure, I can develop a theory of chain complexes over an arbitrary abelian category, but most of the time you just need Hom and Tor over a ring. (Again, see Hatcher.)

Finally, I'm not sure there has been a serious uptake in category theory in the mainstream of some field of mathematics since, I don't know, at least 50 years ago? We've understood for a while now what it's good and not good for. This hasn't stopped people from trying to inject it in fields where it doesn't do any good (e.g. probability), but for that reason those attempts are mostly ignored.

<comment><USER14> > Respectfully, I disagree. The question of what's mainstream and valued by > the community is empirical and can be answered by looking at what's > published in the leading combinatorics journals. And anyone can check those > out and see that categories are basically absent. So as a sociological fact, > I maintain it's far from the mainstream.

I think it is also a reasonable interpretation to take "mainstream" as "pertaining to the main subject matter of the field". Anyway, I think it is the case that the mainstream of combinatorics or probability is yet so big that a particular researcher or even group of researchers can be comfortably in the mainstream and yet have never cared for or even heard of some other line of research that is also mainstream.

The founding paper of combinatorial species [1] has hundreds of citations including many in what I gather are top journals in combinatorics, and even some in the Annals of Probability. So, what are we to make of that? Some people who are serious enough about combinatorics or probability to get published in serious journals have read, perhaps understood, and maybe even taken seriously some of these categorical ideas?

In any case, I respect your viewpoint. In my youth I was a bit category-crazy, trying to use it to organize _all_ of my mathematical knowledge. I'm much more prudent about it these days but I'm still an optimist that we will find more unifying ideas in mathematics through it.

[1] [https://www.sciencedirect.com/science/article/pii/0001870881...](https://www.sciencedirect.com/science/article/pii/0001870881900529)

<comment><USER13> It may the case that combinatorics is large, with mathematicians focused on their own particular sub-specialities, but I still don't believe category theory can properly be construed as "mainstream combinatorics" in any real sense.

Regarding your claim about that paper being cited by papers in top journals, I checked the first five pages of citations in Google Scholar for combinatorics and probability journal papers.

It's cited once in an offhand way in the concluding discussion of "The Cycle Structure of Random Permutations." No categorical concepts are used there. Ditto for the "Independent process approximations" paper (except now cited in the introduction). Another one-sentence mention in the context of background literature appears in "Tree-valued Markov chains derived from Galton-Watson processes." Same for "A Combinatorial Proof of the Multivariable Lagrange Inversion Formula" and "Bijections for Cayley Trees, Spanning Trees, and Their g-Analogues."

There's a one-sentence mention with actual (slight) mathematical content in "Limit Distributions and Random Trees Derived from the Birthday Problem with Unequal Probabilities." But you don't need categories to prove the bijection they're referring to, from what I understand.

In none of these instances is the work used in a substantive fashion, and unless I missed something no paper features the word "category." It's getting cited because authors have a duty to survey any potentially related background literature.

(On page 6 I found "Commutative combinatorial Hopf algebras," which does use a functor form that paper. It was published in a journal that is decent, but very far from the top.)

So, I think we can reject the notion that Joyal's paper has seriously influenced the fields of combinatorics or probability.

I'm sorry to harp on this, but I see claims like yours about the importance of category theory thrown around a lot on here, and often I feel that they're clearly wrong. So I thought it would be good to provide some details this time around.

<comment><USER14> I should have demonstrated my picks. I didn't just look for citation but also looked for at least some nontrivial review of the results of the paper^.

I pick these two papers. The first is literally about adjunctions pertaining to combinatorial species whereas the second devotes an entire section to reviewing the theory and stating results that it uses in a way that I don't really understand. I'm going to read the first paper though because it's relevant to my interests :)

Rajan. The adjoints to the derivative functor on species

[https://www.sciencedirect.com/science/article/pii/0097316593...](https://www.sciencedirect.com/science/article/pii/009731659390073H)

Panagiotou, Konstantinos; Stufler, Benedikt; Weller, Kerstin. Scaling limits of random graphs from subcritical classes.

[https://projecteuclid.org/euclid.aop/1474462098](https://projecteuclid.org/euclid.aop/1474462098)

The fact that I have to go rummaging around for these examples kind of proves your point, doesn't it? I don't think category theory will lead to any fantastic new results in the fields we're discussing, but the bar is quite low for it to be useful as an organizational tool.

^ I searched for the word functor of course! :)

<comment><USER13> OK. The first paper is indeed literally about species and in a good but not top journal. But it's not connected to the mainstream of combinatorics in any way, in the sense that if you aren't _a priori_ interested in species, there's no reason to be interested in the paper.

The second paper is interesting because it's in an excellent journal and about a problem not obviously connected with species. So I agree that it counts as a good example for your case. I also agree with your conclusion – it's an exception that proves the rule, so to speak. Most probabilists have no need for category theory, and most AoP papers don't use categories. (I feel that may literally be the only one?)

I also agree that, to the extent it's useful, it's useful as an organizing principle and not "substantively." I suppose this explains why I feel it's overhyped: mathematicians care about solving problems, and the insights that solve the problems ultimately have to come from some problem-specific observations.

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER15> "We will assume no background knowledge on behalf of the student, starting from scratch on both the programming and mathematics."

This is a fantastic "side effect" of the fact that category theory isn't built on any other mathematical knowledge. You don't even need even any arithmetics for that.

<comment><USER16> At a meta level, Category Theory requires some comfort with abstraction, which really only comes with a mathematical education. So while it may stand apart from much math, it relies on your strong mathematical foundations.

<comment><USER17> As so many undergraduate math textbooks say, "No background is assumed beyond sufficient mathematical maturity."

<comment><USER18> Tautological sufficiency/necessity relativities for an absolute measure are a pet peeve:

"How much salt should I add?"

"Oh, not too much."

Practically guarantees a withering glare from me.

<comment><USER17> That's a really great analogy, actually. You can't tell a brand-new cook "salt to taste," but you can tell a cook with an intermediate level of experience "salt to taste" even if it's a recipe they've never made before. You can't impart the experience in words, pictures, or symbols. You can't add a chapter zero that gets them there. But the right kind of experience will get you there pretty quickly.

I admit it's kind of frustrating that it can't be boiled down to a list of discrete things you need to know, but if I had to explain the difference between me before I had "sufficient mathematical maturity" and me after, I would explain it in terms of habit and confidence and other squishy things that aren't mathematical at all.

<comment><USER19> Giving a precise value for this doesn't work in any case. "Salt to taste" is inherently qualitative.

Most pizza dough recipes quote around 5g of salt for 250g flour. Personally I prefer double that amount, and this is the case with many recipes.

Perhaps specifically with salt there is an insane amount of paranoia about blood pressure. In many ways it feels as irrational as Korean worries about fan death.

On the other hand, giving a "5g of salt" value is a good starting point, to avoid undersalting due to paranoia or oversalting due to inexperience.

<comment><USER17> What they really need is someone to tell them to add less than they probably need, then taste, add more, taste, add more, and expect to over-season and under-season some dishes as they get experience. Salt quantities in recipes have to be short, sometimes way short, so you're stuck learning the process with or without the quantities. I've never seen this explained in a cookbook, at least not in a way that made an impression on me.

Edit: A piece of advice that has stuck with me for a long time, long after I forgot where it came from, is it's a mistake to look for the state in between "not salty enough" and "too salty." That state doesn't really exist, especially when you're feeling nervous! Instead you should look for the overlap where you can perceive the dish as alternately "not salty enough" and "too salty," like that ambiguous drawing that your brain can resolve to either an old woman or a young woman[0]. That advice really works for me, but my wife, who seasons like a pro, thinks it's nonsense, which I think illustrates how subjective the process is and how it isn't information you can impart but rather experience you have to guide someone toward.

[0] [https://en.wikipedia.org/wiki/My_Wife_and_My_Mother-in- Law#/...](https://en.wikipedia.org/wiki/My_Wife_and_My_Mother-in- Law#/media/File:My_Wife_and_My_Mother-in-Law.jpg)

</comment></comment></comment></comment></comment></comment></comment><comment> iso8859-1 Videos of the lectures from last year: [https://www.youtube.com/watch?v=NUBEB9QlNCM](https://www.youtube.com/watch?v=NUBEB9QlNCM)

<comment><USER20> Here's the full playlist: [https://www.youtube.com/playlist?list=PLhgq- BqyZ7i7MTGhUROZy...](https://www.youtube.com/playlist?list=PLhgq- BqyZ7i7MTGhUROZy3BOICnVixETS)

</comment></comment><comment><USER21> These guys wrote "An Invitation to Applied Category Theory." It's an awesome book, and I'm super excited for these lectures.

</comment><comment><USER22> For those who might not realize: IAP is the period between semesters at MIT, roughly most of January. So this is is a quick, accessible introduction, not a heavy semester-long slog.

</comment><comment><USER23> In my experience, Monad, Applicable, and Monoid are probably the only ones I'd use in Haskell, and maybe none of them in languages without good inference and general support.

Pretty wild ideas, though. Fair chance they'd be more confusing than using more specifically named instances, but solid ideas where the class instance documents that you're using the pattern, instead of describing the preferred interface.

<comment><USER24> You've definitely used Functors or Semigroups as well, you just didn't realize it.

<comment><USER25> Here is my problem with these ideas in programming: if you recognize that some common construct is in fact a semigroup or functor, does knowing this actually buy you anything?

I suppose it might help sometimes when designing an abstraction, to guide you to some nice properties, such as easy composition.

<comment><USER26> While playing around with a problem at work involving Markov chains and graph connectivity, I found it useful to know that I could write (in Java) a generic method that performed "exponentiation by squaring" on semigroups.

So, in addition to being able to raise numbers to powers I could also use it on matrices whose elements belonged to a semiring.

That is, I could use the same code on a matrix of doubles with "times" and "plus" (for the Markov chains), as well as a matrix of booleans with "and" and "or" (for the graph connectivity).

(Of course, I could have used special purpose libraries, but these were small problems and it was fun. :)

</comment></comment></comment></comment><comment><USER27> For a humorous use case of types, nothing has beat Aphyr's (of Jepsen fame) "Typing the Technical Interview" here: [https://aphyr.com/posts/342-typing- the-technical-interview](https://aphyr.com/posts/342-typing-the-technical- interview)

If you haven't read it, take a minute...

</comment><comment><USER28> Wow, what a combo! I'd be interested in anything from each of the lecturers, but all 3 at the same course, is amazing.

Category Theory could be the rosetta stone of many things(this is relevant [https://arxiv.org/pdf/0903.0340.pdf](https://arxiv.org/pdf/0903.0340.pdf)).

</comment><comment><USER29> What an odd coincidence that this was posted and on my YT subscribe page: [https://www.youtube.com/watch?v=NUBEB9QlNCM](https://www.youtube.com/watch?v=NUBEB9QlNCM) \- Just posting the video for others to see.

</comment><comment><USER30> David Spivak and other folks at Azimuth Forum[0] have been great at providing high quality discussions on ideas in this course and others. Many thanks.

[0] [https://forum.azimuthproject.org](https://forum.azimuthproject.org)

<comment><USER31> Is this Spivak related to the author of the famous Calculus book?

<comment> dan-robertson David and Michael Spivak are not related

</comment></comment></comment><comment><USER32> This doesn't work at all with HTTPS Everywhere. Just get a page about DreamHost site not found.

</comment><comment><USER33> Will the course be taught live again and if so will those geographically elsewhere be able to attend?

</comment><comment><USER34> Does it compile to WebAssembly VM? Any compilers on Android or iOS? Will it work with Docker? Is it deployable on AWS or Azure?

</comment><comment><USER35> the second i saw haskell i started saying eternally, "ABORT ABORT!"

You are going to have to revive jesus to come up with a functional language that simplifies coding over a procedural one. Especially over an object oriented one.</comment>


Lowering the cost of basic biological research - <AUTHOR> http://www.technologyreview.com/lists/innovators-under-35/2013/visionary/lina-nilsson/ There are also some pretty cool instructables for making your own lab equipment. I recently got to see the OpenFuge and its designer at the Maker Fair a couple of days ago. Hopefully this will lead to DIY bio research in peoples garages. <comment><USER2> One idea I'd would be curious about is how 3D print tech could add to basic biological research. A lot of machines look like simple but customized system of beakers and such. Being able to produce any shape "out of the box" seems pretty useful here.

Edit: Looking up Tekla Labs, it seems they are all about this idea already. It's just the parent puff piece that fails to mention it.

</comment><comment><USER3> most of these equipment can now be purchased secondhand or surplus for less than it would cost hiring someone to build them.

</comment><comment><USER4> Software can probably solve many issues here, like calibrating the devices and processing informations to give scientists meaningful metrics. It may also help fixing or at least detect erroneous data. Great hardware needs to be designed in pair with the software.

Also, just software can help. Now there are iOS apps to count cells by just taking pictures, while labs paid (and still pay) fortunes to get machines/software for that.

</comment><comment><USER5> This is a real kick in the butt, I'm working on a similar project for physics for the last summer. There's a lot that I can translate from my experience of physicist PhD and co-founder of Taipei Hackerspace.

[http://signup.moonpunch.org/](http://signup.moonpunch.org/)

Keep the science rolling!

</comment><comment><USER6> Reproducibility seems like it could be a problem.</comment>


Bluehost kills website of Snowdens Girlfriend - <AUTHOR> http://www.lsjourney.com From archive.org:
http://web.archive.org/web/20130418231028/http://www.lsjourney.com/
NY Post Story:
http://www.nypost.com/p/news/national/girlfriend_left_behind_final_blog_2sgEl3ZhJAVrIlU6low2hK <comment><USER2> To do what he thought was right, Snowden was willing to give up a life with her: [http://www.youtube.com/watch?v=OQc- _zUq1JI](http://www.youtube.com/watch?v=OQc-_zUq1JI). Now that's sacrifice.

</comment><comment><AUTHOR> From archive.org:

[http://web.archive.org/web/20130418231028/http://www.lsjourn...](http://web.archive.org/web/20130418231028/http://www.lsjourney.com/)

NY Post Story:

[http://www.nypost.com/p/news/national/girlfriend_left_behind...](http://www.nypost.com/p/news/national/girlfriend_left_behind_final_blog_2sgEl3ZhJAVrIlU6low2hK)</comment>


Germany launches world's first hydrogen-powered train - <AUTHOR> https://www.theguardian.com/environment/2018/sep/17/germany-launches-worlds-first-hydrogen-powered-train <comment><USER2> In related news, Bombardier is deploying a battery powered train in Berlin: [https://montrealgazette.com/business/local- business/bombardi...](https://montrealgazette.com/business/local- business/bombardier-debuts-battery-train-in-berlin-in-challenge-to-diesel)

Most of the rail system in Germany is electrified anyway. With batteries to power the non electrified bits, why bother with hydrogen?

<comment><USER3> Overhead power lines require maintenance too, and getting 100% coverage often involves disproportionate spend on short sections that are expensive to cover and maintain. Getting rid of masts on those sections - or even whole lines - could be a massive cost saving.

Additionally, Germany is a big train tech exporter, and there's lots of unelectrified route miles in Europe and the world, many of which would be totally uneconomical to electrify.

<comment><USER4> The batteries are supposed to eliminate the need for 100% coverage, though, isn't it?

<comment><USER5> you don't want to remove 100% since you want to charge the batteries somewhere. Also it maybe more economical to keep 1km of power lines after the station when the train is accelerating - main power consumption.

<comment><USER6> That's a great idea. You could just put the overhead charging infrastructure at a few stations on the line. Just enough to top the batteries up. Most of the energy could probably be recovered through regenerative braking, but of course some will be lost through mechanical and air resistance.

This would be so much simpler than electrifying the whole line and much easier to maintain.

This infrastructure is often already at key stations, and so it might require no extra work to implement them. Just more money for the battery powered trains.

<comment><USER7> Gotta put little spinny generator fans and solar panels on the train too. Perpetual motion!

edit: also I don't think your idea will 100% work because it would take some time to charge the trains at the stations.

</comment></comment></comment></comment></comment></comment><comment><USER8> This is obviously great new tech, though one shouldn't see this as a solution to global warming. Until we find a cheaper scale-able way of producing hydrogen that doesn't come from hydrocarbons, this isn't really a solution. Might as well burn the the hydrocarbons directly...

<comment> semi-extrinsic You can say the exact same thing about electric cars.

Hydrogen is not a primary energy source, it is an energy storage and distribution tech, just like batteries.

<comment><USER8> Not if the hydrogen comes from hydrocarbons, which right now is all hydrogen. In this case, it's just an inefficient proxy for fossil fuels...

<comment><USER9> _hydrogen comes from hydrocarbons, which right now is all hydrogen_

It's not! the Scandinavians are investing in "green" hydrogen, you should look at the photos of the giant electrolysers in this PDF: [http://hydrogenvalley.dk/wp-content/uploads/2017/09/FCB- CPH1...](http://hydrogenvalley.dk/wp-content/uploads/2017/09/FCB- CPH17_NELImplementing-green-hydrogen-supply-for-fuel-cell-buses-in-the-Nordic- countries.pdf)

<comment><USER10> Ok, replace the energy source with a solar panel. The only thing this is doing is acting like a battery.

<comment><USER11> Exactly! If we can improve the methods of generating hydrogen, fuel cells have the potential to act as versatile, phenomenally efficient, dirt-cheap batteries, without all the issues of limited metals and dirty production - Being a better battery is a _huge_ deal.

<comment><USER12> The reason that fuel cells are so expensive is because of limited metals. The best fuel cells are made with a lot of platinum. If fuel cells were cheap and did not need the use of limited metals, then they would be a huge deal. Until then, how you produce the hydrogen is a minor detail. (Maybe there have been amazing advancements in fuel cell tech since I last looked into it. Any links?)

<comment><USER13> Batteries don't do that great with the limited metals problem either.

The bigger issue for railroads is range; current battery operated trains have a range of about 40km, whereas this hydrogen train has a range of 1000km. You could have charging stations at every station, but then you run into issues if the distance between stations is more than 40km, or if the charging equipment at a station becomes broken.

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER14> There are locomotives in the US powered by liquefied natural gas. The Florida East Coast railroad's 24 locomotives are all LNG. BNSF is looking into it. It's cost driven; natural gas is cheap right now.

<comment><USER13> LNG was also considered for the French TGVs and the American rail system in the '60s, but then the oil crisis happened.

Fossil fuel prices are extremely volatile, so alternate power sources are actually more financially secure for railroads.

<comment><USER15> The interesting thing about electricity is that it's a great _decoupling interface_ to the power source: you can change the power source and basically leave the remainder of the device/infrastructure as is (not that it's not challenging per se to move say from coal to nuclear to renewable, but hey, if TGV were LNG-based we'd be in a tough bind to move away from it)

</comment></comment></comment><comment><USER16> I've seen at least two comments so far saying that this is only a stopgap in the face of electrification. I do not think this is true, because electrification has very high upfront capital costs, which would not be justified on lesser-used lines.

To back up this statement, I can use some numbers from the Caltrain (California, US) electrification project, where the existing commuter-heavy Peninsula corridor is being converted from diesel-electric to 25 kV overhead electric.

Caltrain quotes the cost of electrifying the line at USD 697 million. See [http://www.caltrain.com/Assets/Caltrain+Modernization+Progra...](http://www.caltrain.com/Assets/Caltrain+Modernization+Program/Documents/PCEP+Cost+and+Funding.pdf)

Caltrain quotes the length of electrified track as "51+ miles", which I'm going to treat as "51 miles". See [http://www.caltrain.com/Assets/Caltrain+Modernization+Progra...](http://www.caltrain.com/Assets/Caltrain+Modernization+Program/Presentations/Cost+Schedule+Update+Nov2014.pdf) pages 4 and 7. The length runs from San Francisco's station at 4th & King streets, down to San Jose Diridon station.

Those two numbers above give us a cost of USD 13 2/3 million dollars per mile. But, that's not fully accurate.

Most of Caltrain's right-of-way is double-track. There are three areas with four tracks (for fast trains to pass slow trains), one area with three tracks (near the Millbrae station), and three areas with more than four tracks (one is Caltrain's yard and shops, the second is the many platforms at San Jose, and the third is the many platforms & yard at San Francisco). See an old Caltrain timetable at [https://web.archive.org/web/20110513180702/http://acm.jhu.ed...](https://web.archive.org/web/20110513180702/http://acm.jhu.edu/~sthurmovik/Railpics/Signal/CalTrain- ETT-No-2.pdf)

Let's say that San Francisco is about one mile of eleven tracks (so, 11 track- miles), each of the three passing points is two miles of four tracks (so, 24 track-miles), Millbrae has a mile of three tracks (3 track-miles), and San Jose has around one mile of twelve tracks (so, 12 track-miles). That leaves around 46 miles left of the 51 original, which would be double-track, giving us 92 track-miles. So, that's 142 track-miles, giving us a cost of USD 4.91 million per track-mile.

Of course, costs may certainly be higher in the US, where electrification (especially for mainline heavy rail) does not happen much (if at all), but still, electrification of an existing line is not cheap. For Caltrain, it makes sense, because this is a heavily-trafficed line in an area with many polluting vehicles (automobiles) that also wants to have a 'green' sensibility, as well as wanting the reduced noise profile.

When you consider freight, there are other issues. For example, in the US, heavy freight traffic lines use gondolas that can support two containers, stacked one on top of the other. That means wires would have to be higher than they would otherwise, and I wonder how how well those extra-extended pantographs would work at higher speed.

<comment><USER17> There are also "partly electrified" possibility e.g. only 10% of track electrified (stations for example). Trains can recharge batteries or supercapacitators there from wire. There already are such existing light rail lines.

[1] [https://en.wikipedia.org/wiki/Battery_electric_multiple_unit](https://en.wikipedia.org/wiki/Battery_electric_multiple_unit)

<comment><USER18> Sydney is doing this for a new light rail line to eliminate overhead wires from the CBD.

</comment></comment></comment><comment><USER19> The problem left is that it's likely still somewhat (or much?) inferior to a lithium battery EV - or if there a good comparison? Energy efficiency is definitely much reduced.

<comment><USER20> Energy efficiency is a red herring. Theey are using surplus hydrogen for this project, i.e. they are getting useful work out of a waste product.

<comment><USER13> Gasoline was originally a waste product.

If hydrogen takes a life of its own that may not be a great thing.

</comment></comment></comment><comment><USER21> French Alstom rolled out a hydrogen-powerded train in Germany.

<comment><USER22> Considering how closely interconnected the EU tech industry is — half the train will be German parts anyway — I don't think it makes sense to try to attribute it to a specific EU country.

<comment><USER23> Counterpositioning Germany and France never lead to anything good, on a global scale.

</comment></comment></comment><comment><USER24> I hope the news get to other countries where fuel trains are numerous (I think India network relies on that)

</comment><comment><USER25> how can it be zero emission?

<comment><USER26> If they use excess electricity during peak renewable energy hours to produce the hydrogen it would be zero emissions. That's an exciting prospect.

</comment></comment><comment><USER27> But why tho?

</comment><comment><USER28> I wondered why they didn't just electrify the line but then I saw the picture and it is so much more beautiful than overhead lines.

But I guess the question is, can you create a third rail that's ~100% safe? Walking along tracks is fun, and I think an important part of rural society.

Then I'd be interested in the cost benefit.

<comment><USER29> > But I guess the question is, can you create a third rail that's ~100% safe?

Regular trains in Germany use 25 kV. Third rail => third system, but what for?

> Walking along tracks is fun, and I think an important part of rural society.

Walking around in the trackbed is not a recommendable activity in Germany.

</comment></comment><comment><USER30> RIP Stan Meyer

</comment><comment><USER31> I'm not sure you're meant to launch a train — launching is for rockets and cream pies.

</comment><comment><USER32> This seems like a very niche solution, as surely in the longer term 100% of railways will be electrified, like in Switzerland.

<comment><USER33> Stringing wires does not make sense for 100% of rail lines due to low volumes of trains -- does anyone make batteries for such occasions, or do you expect some rural lines to be abandoned?

<comment><USER13> SEPTA in Philadelphia actually abandoned many miles of commuter rail because it built a tunnel that could not handle diesel trains.

</comment></comment></comment><comment><USER34> Why not throw a few Tesla power walls on cargo carriage, call it a battery car and swap it for a charged one at stations along the way as necessary..

You just need rails to be able to quickly attach/detach a car, that's much less infrastructure than full electrification.

<comment><USER35> > You just need rails to be able to quickly attach/detach a car

A single attaching maneuver takes 5-10 minutes (from personal experience). Add to that the detaching and driving the carriage off the rail to free it up, and you are quickly at 15-20 minutes, which is unfeasible for most long-distance train rides. Might work with short distances where you already have such a long pause planed in at the ends, but otherwise not so much. It also puts more strain/traffic on the track switch infrastructure at stations, which is already a bottleneck AFAIK.

<comment><USER21> Switching a standard container might be much faster, but you'd need more infrastructure than - crane could be on the rail car though.

<comment><USER36> This problem is solved.

[https://www.cargobeamer.eu/](https://www.cargobeamer.eu/)</comment></comment></comment></comment>


Bypassing Mitigations by Attacking JIT Server in Microsoft Edge - <AUTHOR> https://googleprojectzero.blogspot.com/2018/05/bypassing-mitigations-by-attacking-jit.html <comment><USER2> Related white paper - [https://github.com/google/p0tools/blob/master/JITServer/JIT-...](https://github.com/google/p0tools/blob/master/JITServer/JIT- Server-whitepaper.pdf)</comment>


Mouse found atop a 22,000-foot volcano, breaking world record - <AUTHOR> https://www.nationalgeographic.com/animals/2020/03/mouse-found-atop-volcano-highest-altitude-mammal <comment><USER2> From the paper _Discovery of the world's highest-dwelling mammal_ [1]

> Upper altitudinal limits of wild mammals in the Himalayas and Andes are > generally thought to fall in the range 5200-5800 m above sea level. Such > limits are surely dictated by food availability in addition to physiological > capacities for tolerating hypoxia and extreme cold.

Which explains the significance of:

> we captured a specimen of the yellow-rumped leaf-eared mouse (Phyllotis > xanthopygus rupestris) on the very summit of Llullaillaco at 6739 m

[1] [https://www.biorxiv.org/content/10.1101/2020.03.13.989822v1](https://www.biorxiv.org/content/10.1101/2020.03.13.989822v1)

<comment><USER3> Maybe it was just an adventurous mouse?

<comment><USER4> Danger mouse

<comment><USER5> Mighty mouse i'ld say.

</comment></comment></comment></comment><comment><USER6> No joke my first thought reading the title was that some researcher left his laptop equipment over there.

<comment><USER7> This made me think of this article:

[https://www.theguardian.com/uk/2006/may/17/arts.artsnews1](https://www.theguardian.com/uk/2006/may/17/arts.artsnews1)

<comment><USER8> For others interested, this was solved the next day. [https://www.theguardian.com/uk/2006/may/19/martinwainwright....](https://www.theguardian.com/uk/2006/may/19/martinwainwright.uknews2)

<comment><USER9> That's a variation on extreme ironing, _"an extreme sport in which people take ironing boards to remote locations and iron items of clothing. According to the Extreme Ironing Bureau, extreme ironing is "the latest danger sport that combines the thrills of an extreme outdoor activity with the satisfaction of a well-pressed shirt"_ ([https://en.wikipedia.org/wiki/Extreme_ironing](https://en.wikipedia.org/wiki/Extreme_ironing))

<comment><USER7> > That's a variation on extreme ironing

I'd say an _extreme_ variation of it ;)

</comment></comment></comment></comment></comment><comment><USER10> 22000 foot are 6705.6 meters.

<comment><USER11> Although beware excessive precision: [https://blog.plover.com/physics/precision.html](https://blog.plover.com/physics/precision.html)

Maybe 6700 meters, to match the 2 digits of precision.

Although from the article: "he encountered another yellow-rumped mouse even higher than previously sighted, atop the very summit of Llullaillaco, at 22,110 feet" -> 6739 meters

<comment><USER12> I feel like this is still an unsolved notational problem. Let's say I want to give you the elevation of Mt Everest in feet to 3 sig figs. I could say 29,000 ft, but that'd be misread as 2 sig figs. So I have to say something like 290 _10^2 , or 2.90_ 10^4 , to convey the correct information. Or just 2.90e4. Maybe there's nothing better?

Famously, the original surveyor of Mt Everest calculated 29,000 exactly but lied and added 2 feet to make it 29,002 so that people would understand he meant 5 sig figs, not just 2. That's one way of solving the problem ...

<comment><USER13> It's easy enough to invent a notation, like

        29,0·00

Maybe this new standard notation was born today on HN!

<comment><USER14> The usual way is a line. It can be faked here with code formatting (4 spaces to force mono font) and underscores:

        ___
        29000

<comment><USER12> It bothers me that this overloads the notation for repeating fractions. I guess there wouldn't be a use case requiring both in a single number, but you can imagine multiple numbers on the same page using this formatting for different purposes and it being confusing.

And it's fine for writing out by hand or in TeX (I assume), but good luck using it in any other context as we see here! Ideally a notation would be keyboard-friendly, at least for something with as wide an applicability as this anyway.

But this is certainly a good starting point.

<comment><USER15> > multiple numbers on the same page using this formatting for different > purposes and it being confusing.

I think it's unambigous at least: 2̅9̅0̅00 vs 11̅.̅4̅2̅8̅5̅7̅; sigfigs has overline at the start, while repeating has overline at the end.

</comment></comment></comment></comment></comment></comment></comment><comment><USER16> There's a spider in the Himalayas that lives at even higher altitudes, living on rocks warmed by the sun and surviving on gnats and flies that get blown up the mountain from temperate climates.

<comment><USER17> Curiosity led me to the Himalayan jumping spider:

> Euophrys omnisuperstes (the species name means "standing above everything"), > the Himalayan jumping spider, is a small jumping spider that lives at > elevations of up to 6,700 m (22,000 ft) in the Himalayas, including Mount > Everest, making it a candidate for the highest known permanent resident on > Earth. They are found among rocky debris, feeding on tiny, stray springtails > and flies.

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

</comment></comment><comment><USER18> (Aw, I read "Moose" and was so disappointed when I clicked through.)

As a random tidbit there's also a bizarre tiny pink armadillo that lives up there. It lives in holes and has a plug-shaped rear end. It's one of those critters that, when you see it, makes you go "C'mon Nature, you're putting me on, eh?"

<comment><USER19> Surely not? The point of the find is that this is the first time a mammal has been found at such an elevation.

<comment><USER18> Sorry, I meant the high mountain desert, not all the way up there where the mouse is.

</comment></comment></comment><comment><USER20> They should give the mouse an MRI.

[https://www.scientificamerican.com/article/brain-cells- into-...](https://www.scientificamerican.com/article/brain-cells-into-thin- air/)

<comment><USER21> If you give a mouse an MRI, he'll ask for a PET scan.

<comment><USER22> And when you give him an ultrasound, he'll ask for sound-conducting jelly.

</comment></comment></comment><comment><USER23> >It's incredible that anything could live that high, at 20,340 feet—there is no vegetation, and seemingly nothing to eat.

There's clearly vegetation in the background of the photo.

<comment><USER24> Seems like the photo was taken at a lower altitude. What the summit actually looks like can be seen in the video: [https://www.youtube.com/watch?v=DGUDXs8Z31A](https://www.youtube.com/watch?v=DGUDXs8Z31A)

</comment></comment><comment><USER25> > The work has received funding from the National Geographic Society and the > U.S. National Institutes of Health, as better understanding adaptations to > high altitude life is "potentially relevant in treating a number of human > diseases that relate to... problems with oxygen delivery and oxygen > utilization," he says.

I often wonder how discoveries like this ultimately manifest into actionable technology. Are they studying cell structure? DNA? What does that process look like?

> The results could also aid doctors in treating altitude sickness and coping > with life at high altitude or elsewhere where there are low levels of > oxygen.

That makes me wonder if the end goal is some kind of pharmaceutical drug.

Very interesting nonetheless!

<comment><USER26> I think the reality is that researchers justify themselves to grant writing organizations in whatever way they can but are often just doing science for it's own sake.

Anecdotally, I watched a talk about how the structure of the ribosome was solved, and the researcher mentioned that they justified themselves to grant writing organizations by saying it would help develop antibiotics - which did turn out to be the case, but they described themselves as feeling amused rather than vindicated.

I believe it was this talk.

[https://www.youtube.com/watch?v=TRIDCQM3d7I](https://www.youtube.com/watch?v=TRIDCQM3d7I)

<comment><USER27> Bingo. While understandable, I fear the need to justify nearly all research by potential foreseeable gain limits our ability to invest in truly fundamental science.

<comment><USER28> Well, researchers have learned to play the game and with enough creativity you can make up potential applications for grant writing purposes.

</comment></comment></comment></comment><comment><USER29> "These creatures you call mice you see are not quite as they appear, they are merely the protrusions into our dimension of vast, hyper-intelligent pan- dimensional beings." ~ Slartibartfast, The Hitchhiker's Guide to the Galaxy

<comment><USER30> I think he was just trying to hitch a ride from a high point before the impending destruction of Earth

<comment><USER31> It's an experiment upon humans of course. Be found where no mouse should be; see how humans react on Hacker News. (-:

</comment></comment></comment><comment><USER32> Not just any mouse, a "yellow-rumped leaf-eared mouse". And he's _adorable_!

</comment><comment><USER33> How does this altitude compare with ground level on mars? Air pressure wise.

<comment><USER34> Air pressure on Earth at 6700m is around 430mBar. [0] Pressure on Mars (at the artificially defined zero-level) is 6 mBar [1] and twice as much at the lowest point of Mars' surface [2], Hellas Planitia, which is a huge crater in the southern hemisphere with its lowest point around 9000m below zero.

[0] [https://www.wolframalpha.com/input/?i=air+pressure+6700m](https://www.wolframalpha.com/input/?i=air+pressure+6700m)

[1] [https://de.wikipedia.org/wiki/Mars_(Planet)](https://de.wikipedia.org/wiki/Mars_\(Planet\))

[2] [https://en.wikipedia.org/wiki/Hellas_Planitia](https://en.wikipedia.org/wiki/Hellas_Planitia)

<comment><USER33> Ah thanks! So the mouse couldn't live there ...

<comment><USER35> the lack of oxygen would get it first i think :)

</comment></comment></comment></comment><comment><USER36> How long was the mouse's tail?

</comment><comment><USER37> In 1927 col walter snetterton disappeared while trying to cross the Andes by frog. Maybe someone tried with mice?

</comment><comment><USER38> I read it as MOOSE and I was like HOLY CRAP!

</comment><comment><USER39> Who moved my cheese?

Good book

</comment><comment><USER40> Oh, an actual mouse, not a computer mouse.

</comment><comment><USER41> Nature's resilience, adaptability, and resourcefulness underscores how much we have to pollute it to cause so many extinctions, deserts, and wastelands. How much beauty do we have to see or lose to change our values from growth at all costs and externalizing costs to enjoying what we have and taking responsibility for how our behavior affects others?

</comment><comment><USER42> It seems convenient that the scientists who arranged an expedition to look for mice at high altitude find one higher than any mouse seen before. My skeptical side wonders if the guy who was obviously at the peak before Jay Storz in the video, brought the mouse up, and let it go so that it could be found. Hopefully unrelated researchers who don't use the same guides, etc... are able to also find mice at similarly high altitudes.

<comment><USER43> That's not skepticism, that's conspiracy theory. The previous record elevation for finding a mouse was _on the same mountain_. It would be more surprising if the first expedition actually found the elevation limit of these mice, rather than the follow-up expedition that was specifically investigating whether they ranged any higher.</comment></comment>


Australia sues Facebook over Cambridge Analytica - <AUTHOR> https://techcrunch.com/2020/03/09/australia-sues-facebook-over-cambridge-analytica-fine-could-scale-to-529bn/ <comment><USER2> The fact that we (the UK) only fined Facebook £500k [1] is an utter scandal. You can probably say $529bn is too much, but the appropriate amount might be somewhere in the middle of the two...

1\. [https://techcrunch.com/2019/10/30/facebook-agrees-to-pay- uk-...](https://techcrunch.com/2019/10/30/facebook-agrees-to-pay-uk-data- watchdogs-cambridge-analytica-fine-but-settles-without-admitting-liability/)

<comment><USER3> Facebook's revenue in 2019 was $70bn. $529bn is 7 times this. I don't think Facebook even generated close to $529bn during the entirety of its lifetime. This is not "probably say": $529bn would just not work.

EDIT: If the goal of the fine is to just kill Facebook's presence in Australia, then yeah, I guess it works. But in this case, Facebook won't pay that fine. They'll just stop operating in Australia - in other words, they'll stop taking advertiser money from there. At worst, Australia's govt will block access to FB.

<comment> munk-a Still, it sounds like a reasonable amount for, as a company, designing a system that helped compromise an election.

If FB needs to declare bankruptcy and shutter their doors then nothing of value will be lost.

</comment></comment></comment><comment><USER4> No $529BN fine would ever actually happen.

That would be considered economic warfare and the US wouldn't allow it.

<comment><USER5> Why not? Isn't Australia free to not allow Facebook to operate in their country if they don't pay a fine? And if the US prevents them from doing so by retaliation or sanctions, that would actually be closer to warfare.

<comment><USER6> The US almost certainly would, at least it did most recently when France wanted to put a digital tax: [https://www.theverge.com/2020/1/23/21078574/france-us- digita...](https://www.theverge.com/2020/1/23/21078574/france-us-digital-tax- deal-negotiations-tariffs-postponed-trump)

A consumption tax is a pretty good way to tax foreign companies though imo, as long as your domestic market is desirable.

<comment><USER7> > _The US almost certainly would_

What happened with China?

I know FB isn't really operating in China. (At least no one I knew in Ningbo had it?) So did we sanction China for that or how did that all work? Because, and I don't know if we did or didn't, but if we didn't sanction China, why sanction Australia? Was that situation different somehow? (Other than just "China's richer").

</comment></comment></comment></comment><comment><USER8> facebook could turn their public perception around in a second by declaring that it is not a political platform and banning political ads. I honestly don't care how much they market me to coke and pepsi, but the impact on democracies is way creepier...

<comment><USER9> The problems with facebook run far deeper than just politics. If you think that doing what you suggest would change perception you are sadly mistaken.

</comment></comment><comment><USER10> Now THIS would be a fine that Facebook would surely feel!

I am assuming this is some Class Action suite ? Or is this different as its from the privacy watchdog ?

<comment><USER11> It's a government body. So the Plaintiff in this case is presumably the Australian Federal Government, in a case in our Federal Court.

[https://www.oaic.gov.au/](https://www.oaic.gov.au/)

<comment><USER10> I have an unexplainable urge to scream : "THE LIBERAL GOVERMENT!!!"

This is really cool news though, it's about time that Facebook take some serious ownership of this mess.

</comment></comment></comment><comment><USER12> yeah that's real likely

</comment><comment><USER13> Good.

<comment><USER14> Very good indeed.

Its a fine fit for a multi-billion dollar company. Unless they get it significantly reduced somehow...

<comment><USER13> Any fine against Facebook is good.

</comment></comment></comment><comment><USER15> And when the actual fine is just $10bn, the markets will reward FB by increasing their stock price.

<comment><USER16> Those aren't rewards. The price goes down at the opposite of the suit and the fine gets priced in with a given risk factor, and if they end up doing better than expected, then the price will adjust to integrate that new knowledge. It's still lower than if they'd never gotten fined (though perhaps not lower than if they hadn't unethically made that money in the first place)

</comment></comment><comment><USER17> sounds like excessive fines/bail violation of the 8th amendment lol

<comment> munk-a How is this related to the 8th referendum[1]?

1\. [https://en.wikipedia.org/wiki/1977_Australian_referendum](https://en.wikipedia.org/wiki/1977_Australian_referendum)

</comment></comment><comment><USER18> Spoiler: they'll get away with a couple of mil

</comment><comment><USER19> It's a good start to negotiations. Maybe they'll get $2B from FB. FB will likely fund the current politicians' re-election campaigns in a quid-pro-quo to drop/reduce charges.

Either way it's a good move on the part of governments to apply pressure to a known shady actor.

<comment><USER20> Not all countries do politics the same way as the US.</comment></comment>


Is Linux About Choice? - <AUTHOR> http://www.islinuxaboutchoice.com/ <comment><USER2> Redhat employee being against choice is somewhat expected. It's almost inevitable for big tech corporations to promote such attitudes into their culture. But choice is what makes Linux so much different from other desktop OSes. Like I was on Ubuntu distros for a decade, but was never really satisfied with all the bloat, change for the sake of change, release upgrades, outdated packages. Now I'm moving to Arch, pretty much the opposite of all that. And it would be impossible for Arch to exist without Linux being about choice.

</comment><comment><USER3> >no, seriously: Linux is a kernel, and has nothing to do with choice. It has, however, _something to do with ethics in games journalism_.

What?

</comment><comment><AUTHOR> For what it's worth, I completely disagree with this site. Even if you only look at Linux as a kernel, one can compile it with whatever combination of options one likes.

But Linux is an entire ecosystem, not just a kernel. One of the advantages to the openness of the Linux ecosystem is that there are usually at least two options for whenever there could conceivably be a choice. I like that opportunity for customization.

When people say Linux is not about choice, I usually find it's because they're defending systemd. I'll be the first to admit that systemd has some good ideas. But I don't like how it spreads like kudzu across the system until common, low-level programs depend on systemd and systemd depends on their own versions of those programs instead of relying on a commonly agreed upon interface.

</comment><comment><USER4> Odd contrast between the garishly huge "no" and the flyspeck-sized body of the page</comment>


Slavery Footprint - Made In A Free World - <AUTHOR> http://www.slaveryfootprint.org/ <comment><USER2> Very pretty, but would like to see more details of the methodology. Trades usability/transparency for visual flair.

Also, the social media functions seem to be broken. Tweeting to share my results tweeted a blurb about the site, but no link at all.</comment>


Best Password Manager Apps to secure your passwords - <AUTHOR> https://nexthive.com/5-best-password-manager-apps-for-2019/ <comment><USER2> KeePass is an excellent solution. You can even store the kdbx file on a remote server and access it on different devices.</comment>


"let" in python (2014) - <AUTHOR> https://nvbn.github.io/2014/09/25/let-statement-in-python/ <comment><AUTHOR> Coming from lisp, I was looking for a "let" in python. Found a recent reddit discussion here: [https://www.reddit.com/r/Python/comments/41yr58/let_statemen...](https://www.reddit.com/r/Python/comments/41yr58/let_statement_in_python_2014/)

I especially find myself wishing for a let in these instances: [https://www.reddit.com/r/Python/comments/41yr58/let_statemen...](https://www.reddit.com/r/Python/comments/41yr58/let_statement_in_python_2014/cz6gpzc)

While the canonical answer is to assign to a local variable within a function, sometimes I abhor writing functions for such small tasks.

</comment><comment><USER2> Smart hack, but IMO gives too little for me to be bothered to add a dependency.</comment>


Why you will love nftables - <AUTHOR> https://home.regit.org/2014/01/why-you-will-love-nftables/ <comment><USER2> I would really love to see "pf" on Linux.

When I began using Linux, "ipfwadm" had just been incorporated into the kernel. It was replaced in 2.2 by "ipchains" which was replaced in 2.4 by "iptables". Now we have "nftables".

I'll admit to not knowing much about nftables but from what I've read about it in the last few days, it's still not even close to what OpenBSD's "pf" is capable of.

Ahhh, well, I can wish, right?

<comment><USER3> I've heard this about every linux firewall, can you give some good examples of what either iptables or nftables can't do that pf can?

<comment><USER4> Many people use something like denyhosts or fail2ban to help with brute force attacks. PF has built-in support for building rules with options which will throw potential attackers into a 'penalty box' based on certain factors like connection rate.

<comment><USER5> You can use iptables for that:

      $ sudo iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW -m recent --set --name SSH

      $ sudo iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW -m recent --update --seconds 60 --hitcount 8 --rttl --name SSH -j DROP

Copied from [http://kvz.io/blog/2007/07/28/block-brute-force-attacks- with...](http://kvz.io/blog/2007/07/28/block-brute-force-attacks-with- iptables/) but I agree that pf ist just much more sane config wise.

<comment><USER3> Since nftables is supposed to be backwards compatible, I'd guess it can do this too. I wonder what it'll look like for that. A lot of the other syntax looks nicer, i suspect that this will be better too.

</comment></comment></comment></comment></comment><comment><USER6> nftables sounds like a great example of why you should learn compilers: [http://steve-yegge.blogspot.com/2007/06/rich-programmer- food...](http://steve-yegge.blogspot.com/2007/06/rich-programmer-food.html) You can write reams of code that work, but still have limits, and overcoming those limits would require further endless reams of code (iptables). Or you can write something simpler that breaks the problem down into primitives which a compiler will let you put together arbitrary ways, and despite being more flexible, is still less code (nftables).

</comment><comment><USER7> snapshot in case the server is overwhelmed : [http://archive.is/M1R6K](http://archive.is/M1R6K)

</comment><comment><USER8> Being able to load a whole configuration with nft -f instead of having to hack a script to do the same is also a nice feature (makes it more pf-like)

<comment><USER9> This is easy with iptables too:

      iptables-restore < yourfilterfile

<comment><USER8> Yeah.. true.. still prefer the config file format[1] nftables brings along though.

[1] [https://home.regit.org/netfilter-en/nftables-quick- howto/](https://home.regit.org/netfilter-en/nftables-quick-howto/)</comment></comment></comment>


Say no to new clients: "For that reason, I'm out." - <AUTHOR> http://menwithpens.ca/say-no-to-new-clients/

<comment><USER2> I'm not so sure I agree with this reasoning. I agree with asking questions about their business and strategy because such questions can lead to interesting conversations, but to outright refuse to do someone's project because _you_ don't think it'll work is the epitome of arrogance.

Lots of people want BS projects and lots of people also only really learn through experience. That $10k project that is "obviously doomed to fail" might give them a fairly cheap education in business that will lead them to their next, more profitable project. Or, perhaps, they'll figure out they're not getting the results they want, ask why, and make the necessary changes to make it work with that $10k thing that's been built. Not everybody is irrational or unreasonable in the face of failure. (Also, that BS project might actually succeed too.)

Bear in mind that most businesses fail, and someone's first and second businesses are even more likely to fail. Trying to save someone from failing in this way is depriving them of the experience that they need to be successful later. It's akin to trying to stop a toddler from falling but also preventing them from learning to walk. Experience is a valuable teacher and we don't need to be out trying to save the world from failure. Failure is necessary.

One more example: if I go to my hair stylist and ask for it all to be shaved off, I'd hope that he'd tell me I wouldn't look good with a buzz cut. However, if I insisted, I'd also hope that he'd do it anyway.

Perhaps the only three good reasons that spring to mind for turning away a prospect are a lack of ability or willingness to pay, an inability to complete the project, and a severe personality conflict that's going to lead to lots of drama in the working relationship.

<comment><USER3> Mostly agree. The customer is always (in their) right to be wrong. (As long as they pay for it.)

However one rule my Dad made sure to remember was that although someone deserves "a real beating" (obviously figuratively speaking here) you should always avoid being the tool used for that.

</comment></comment><comment><USER4> Saying no to a customer in such circumstances - and this goes against the grain here judging by the other comments - is just fine.

If you are working on something you don't believe in you'll be working at a lower fraction of your capacity, whether you know it or not. Better to leave that job for someone who does believe in it, and who by virtue of that fact will make it a little bit more likely that the project succeeds anyway.

There is absolutely no harm in being honest, with your customer _and_ with yourself. Working for a long time on a project you don't believe in won't have a happy ending.

<comment><USER5> Plus the ongoing psychological weight of knowing you are not doing your best work, and/or you're doing great work that is destined for the junkyard, or you're casting pearls before swine… not to mention failed projects don't look great in your portfolio.

Saying "No" is a way to honor yourself, protect yourself from hidden opportunity costs (both real & psychological), and feel good about what you're doing.

</comment></comment><comment><USER6> I totally disagree with this. You cannot judge the potential success of a clients idea. As stupid as it may sound. As big or small it may be. You don't know if it will succeed. Your job is to build it for them, not to judge the idea. It is _their_ job to try and make the idea work for them. I have personally built things that sounded very stupid to begin with, and then went on to make lots of money to my client. Had I been so arrogant, I would have been the wall that kept my client from changing his/her life for the better.

One of the downsides of the tech bubble is that some programmers get a sense of entitlement because they are such a precious and valuable genius. Not really. Programmers are not more special than other professionals (or even more special than the people who pick up my trash). Don't believe the hype. You might one day find yourself working at Burger King after the bubble bursts.

</comment><comment><USER7> The only problem is that it might be too arrogant for us developers to tell clients what will or will not work. In pre-twitter days, if a client asked me to build something like twitter, I would think he would fail. So it is like a blog but with 140 character restriction? I would also think wikipedia would not work. Why would anyone take time and effort to contribute useful information for free and how do you guarantee the integrity of the information. Of course, right now, it all makes sense. But it is very arrogant to think that you know what will succeed or fail.

<comment><USER3> I still have a problem with twitter though. Every time I think of it I start thinking what a brilliant tool it could have been if they had focused on group internal messaging etc.

Obviously I'm not their target demographic ;-)

</comment></comment><comment><USER8> How to, politely, say "no" to clients and remain friendly afterwards is probably one of the more useful skills I've acquired in my career.

And "stupid" clients without an obvious business plan, etc. are not the sole reason to say "no". Much more common is the client who you _can_ work with, but it's not the best option for you or the client. Because they're looking for the lowest price, not value received. Because they're looking at something that's only 60% in your sweet-spot, and isn't interested in the other 40% of your skill set. Because they don't have the budget for your current rates. And so on.

</comment><comment><USER9> The difference between "The Dragon's Den" and having a potential client approach you with work is that the Dragons are being asked to _partner_ with the client, not do work for them.

If a potential client come to you with a questionable business and asks you to do work for them _as an investment_, you probably should walk away. If they want to pay you, then do what you think is best.

</comment><comment><USER10> This is a bit arrogant and misguided. As another commenter pointed out, if you go to a hair dresser, you do get suggestions about what will look good on you, but the hair dresser won't refuse service if you go against the advice. As a developer, you can pick and choose your projects. If you don't want to work on ideas you think aren't good enough, cool; but don't make generalizations. Doing paid work for someone isn't the same as being a co-founder(as in investing or working for free).

<comment><USER11> When Britney Spears shaved off all of her hair herself, it was because the hairdresser flat-out refused to do it for her.

<comment><USER12> And on the other hand, there are all my hairdressers over the years who asked me what I wanted and then did whatever it was that wasn't like anything I wanted.

So, flipping the allegory now, if a client comes to me and asks me to develop a Twitter, would it be OK if I deliver an eBay instead?

My conclusion is that it's probably time to treat our hairdressers like they're developers and instead of just saying "yeah, that's perfect" when we really hate the cut, tell them that we are not happy with the results and that we will be back once the hair grows for another iteration, and that we'll pay once we can go live with the haircut as we specified it.

Either that, or stop using irrelevant allegories.

</comment></comment></comment><comment><USER13> The author should clarify whether he's acting in the role of a consultant to his client or a contractor for them. The questions he's raising definitely signal "consultant" but his price signals "contractor". The expertise he thinks he's being hired for is "make my project successful" (consultant) but is probably "build this thing for me" (contractor).

Consultant's generally have to spend a lot of time persuading their customers to follow their advice, and charge high rates to make sure that they do. Contractors focus more on efficient delivery of their work, and let the customer sort out what to do with it.

Note that I'm using the titles consultant and contractor in their extremes. Most people who have one of these titles actually do both jobs during the course of a customer engagement. It helps to be aware of which one you're doing when you're doing it, though.

</comment><comment><USER14> So a hypothetical scenario: a client says to me "I've got this great idea to compete with Facebook by using red navbars instead of blue". Should I refuse the job because their idea won't work?

I would clarify what I can and can't do for them: "I can build a working product that will scale to 10,000 concurrent users assuming you're prepared to pay $5K per month in hosting costs. I can't deliver millions of users, protection from patent infringements, etc."

Also, if I think the idea is going nowhere, I would be careful about being paid up front.

If their happy with my terms, I'm happy to receive their money.

</comment><comment><USER15> I used to do this a lot more. However, at some point I realized I would certainly have shot down twitter. Since then I've hopefully been less arrogant.

<comment><USER16> Exactly. If you've politely let the client know you're not convinced by the business model, the client still wants the work done, and you need the work, why refuse?

</comment></comment><comment><USER17> Horsepucky. Most of my clients are entrepreneurs. Many fail. That's just the way it goes. But of all my client projects, the one that I was most sure was a total waste of time and effort is the one that has been the most successful.

If I were so good as to be able to tell which _ideas_ are going to succeed as products, I'd be sitting next to Mark Cuban on Shark Tank and making fun of how poor he is. Until I gain that expertise, I think I'm going to let my clients follow their dreams and help them out as much as I can.

</comment><comment><USER18> A lot of the books on consulting I read emphasized client at best in the long run can pay only proportional to the actual value of the engagement. And clients are often coming to you for advice beyond the step they are paying you for. So I like the article, there really is no reason not to tell the client not to pay for pursuing what you feel is a bad idea. It is certainly up to the client to make the final determination, but you have to be honest and very generous in communication.

</comment><comment><USER19> I'm a developer, not a business analyst. My perspective on the veracity of an idea is pretty irrelevant and in most cases ignorant.

</comment><comment><USER20> I appreciate the writeup. Have a close friend trying to push a new business idea on me that I am positive she is not ready for. Would be great to cash a big check, but not worth being blamed for the buz failure when her motivation fizzles.

</comment><comment><USER21> Isn't this similar to the car salesman interviewing me about how I will drive, who I will give a ride to etc. and then refusing to sell me the car? Doesn't sound like a great strategy for the seller. How about just sell the car?

</comment><comment><USER22> It is usually my luck that I get approached by big vision sales types doing a project that requires some niche of what I do well. It is the distraction of the additional project that degrades the quality my work. Have to say no.

</comment><comment><USER23> I run a small web agency and would like to see similar thoughts, issues with client relationship, building trust, etc. Are there nice blogs/articles that can help?</comment>