Why I Let My Students Cheat On Their Exam - <AUTHOR> http://www.zocalopublicsquare.org/2013/04/15/why-i-let-my-students-cheat-on-the-final/ideas/nexus/ <comment><USER3> I loved this approach until I read the exam question. After that, I only liked it.

It would have been more interesting to see an exam with question like "is the population of x in hardy-weinberg equilibrium", where x is something students should know something (but not everything) about if they've been paying attention. It would be possible, but not easy, for a very well prepared student to do the research and figure it out (or at least write an intelligent answer) in an hour. Some bright students who haven't studied much probably would be able to research quickly and come up with a good answer, especially if they split up the task. Some people will clearly be vastly more valuable to teams than others.

In short, I think the professor here picked a question that tilts too heavily toward collaboration. If this approach is really going to work, you need to induce some reluctance among the very well prepared, who may realize that their friends who spent more time preparing for the non-collaborative physics exam will be getting a relatively free ride.

I guess I just don't think this quite brought out the nastiness that would truly arise in a state of nature - something of course I understand he'd rather avoid!

</comment><comment><USER4> 1\. This obviously wasn't cheating since it was within the prescribed parameters for the exam. Some exams are open book, some are open note, some are even take home with no limits.

2\. The highest score and thus most insightful and highest quality work, according to the professor's own evaluation, came not from collaboration but from one of the 3 lone wolves.

<comment><USER5> The average was higher than that of prior classes. Also, it is implied that the lone wolves may have had access to some of the work the mob was producing, enabling one of them to get ahead by simply correcting a few mistakes without giving them back to the mob.

<comment><USER6> She explicitly stated so: _Although the Wolves listened and contributed to discussions, they preferred their individual variants over the Mob's joint answer._

</comment></comment></comment><comment><USER7> When I was in high school my classmates and I found a document from a previous year that amounted to a superset of all the questions my philosophy teacher was going to put in test.

Since some of the questions were pretty hard we ended up studying really hard together to try and crack them before tests.

Though what we did was somehow against the rules I feel I learned a lot more by studying the questions collaboratively than by studying on my own.

I later found this form of collaboration extremely rewarding and effective during university. We spent many afternoon trying to crack hard problem sets and explaining them to one another.

<comment><USER8> It has always puzzled me why a professor would be willing to repeat the answers from previous years. Some account that people that work "harder" would be solving previous exams, but this is given that the exams are available to all the class (which is a prerequisite for this argument to be true).

I've found myself in classes where a group had exams, problem sets and other information from previous years (and solved) and they hid and refused to share those.

<comment><USER9> It is _hard_ to come up with entirely new problems for every exam every year. That doesn't mean that doing so isn't important, but it really is time consuming and a whole lot of work. It's also painfully easy to _think_ that you've changed things enough for the question to be "new" compared with examples from class or homework or previous years' tests, only for some student to recognize it enough to regurgitate some memorized solution rather than actually thinking.

So while I'd never say that repeating questions is a good thing, I can't be too hard on folks who do (intentionally or not).

<comment><USER10> For some students it also can serve to mitigate exam shock (speaking to high school level anyway, which is my area). Finding a familiar, or even roughly familiar question can mean a nervous student has an entry point into the exam.

I quite liked the article. It'd be interesting to see if the benefits persisted over multiple groups though. I tend to see engagement increase when rules are changed and students need to figure out how to address the problem in a new way, regardless of whether they are collaborating or not. (anecdotal evidence there only sorry ;P)

</comment></comment></comment></comment><comment><USER11> _Instead, they were changing their goal in the Education Game from "Get a higher grade than my classmates" to "Get to the best answer."_

The goal shouldn't be "Get a higher grade than my classmates", it should be "Get the highest grade possible". And the goal for the teacher should be "Translate each student knowledge data into a numeric value", which is somewhat orthogonal to the experiment.

<comment><USER12> Shouldn't the goal be to "Learn the most possible"? I know, it's not quantifiable, so maybe it doesn't qualify as a goal at all, but it concerns me when people act like the purpose of education is to get grades.

<comment><USER13> You'd be surprised to learn how many college students goals aren't actually to "Learn the most possible."

<comment><USER14> It's not that any of us are surprised, it's that _that_ is the core problem with the construct of the educational system. The system encourages this 'number juicing' through whatever means.

During the course of a class, if as much education is given to each individual possible, then at the end of the class what does the actual grade matter? These grades turn out to be a poor proxy for things like earning, ingenuity, creativity, changing-the-world, or for that matter even grokking the materials. The only thing for which they're (maybe) a valuable proxy is 'how well can this student juice the grade of the next course in the line' -- a question whose answer ultimately adds no value to society.

<comment><USER15> > These grades turn out to be a poor proxy for things like earning, ingenuity, > creativity, changing-the-world, or for that matter even grokking the > materials.

It's unfortunate, but in my department about 80 % of the students go up to med school. The GPA plays a great part in determining just what school will accept you, which in turn has _massive_ impact on your future earnings.

</comment></comment></comment></comment></comment><comment><USER16> I had a professor who used a similar concept of fostering active discussion and debate within the classroom, except he did it for every lecture. He would present a concept, then ask us a series of questions about it. Students would first think on the question and vote on their own, then the question was opened to discussion and debate. After the topic had been hashed out we would re-vote. Often times the difference between the first and second votes were significant, sometimes resolving a split opinion and other times the majority would change their minds.

It was a lot of fun, and easily the best and most informative experience of my educational career.

<comment><USER17> Most of my high school education was like this. It's fairly common in "alternative" schools like Montessori, Waldorf, Essential, or Sudbury schools.

</comment></comment><comment><USER18> It's not cheating if everyone is following the same rules. Cheating is almost by definition an unfair advantage, when this was pretty close to a level playing field.

<comment><USER19> And how about the students in different sections not taught by this teacher who have a closed-book no-collaboration final exam?

</comment></comment><comment><USER20> I would be curious what the students thought of the process.

I am sure that the essay was good. I am sure that some learned a lot. But how many just road coattails and didn't learn much other than how to copy? In a game like this where everyone stands to gain, and nobody loses, the incentives are to let everyone participate because the cost of riding is free. How many took advantage of that?

Also on a task like this, individual personalities of key figures matter a lot. My guess is that just a few individuals were responsible for a lot of the dynamics.

The whole exercise would have been more interesting - and more competitive - if he had started with a grading scale at the start, same rules, but said that he would rank answers against each other, with multi-way ties being ranked at the median of the group. (So if 5 people tie for 3rd, they will all be scored as 5th.)

This would push cooperation/competition to a new high.

<comment><USER21> That's a good approach for a generic class on game theory.

It's not so good for the specific case of animal behavior, in which the whole herd will indeed often prosper or suffer at once.

</comment></comment><comment><USER22> And yet again, here's 25 comments from the Hacker News Pedant Squad to remind you that it's not REALLY cheating if the teacher lets you, in case you only recently disembarked from an 18-wheeler full of turnips.

<comment><USER23> What's unfortunate about such comments is that such departures from the norm actually are considered bad ("cheating") according to the ideology of mainstream education. The article's author wasn't the only teacher with the bright idea to have collaborative tests, where he was willing to answer whatever the students asked. I know of at least one teacher who was forced to stop.

Education could look very different, and more diverse.

Universities have certain functions in society. If they don't fulfill those functions, they won't get government and corporate funding. Even Salman Khan explains that one important function of schools is to subjugate, fashioning people into obedient cogs. (In his "The One World School House", in the chapter "The Prussian Model".)

</comment></comment><comment><USER24> I am constantly surprised that we have a 'moral' aversion to cheating. IMO school teaches two strategies for success. 1.) work hard within the rules and 2.) cheat but don't get caught. Each is equally valid in society, even without a 'moral' component.

<comment><USER25> The 'moral' aversion to cheating I believe comes out the very game theory and evolutionary behavior that this post talks about. When society sets up rules and systems, there is a maximum amount of cheating/parasitism that it can withstand before the system breaks down, and everyone (at least the majority of the non-cheaters) loses out (assuming a 'good' system). I think we all know/feel this at a very deep level, and understand that if we want to set up and maintain cooperative systems, cheating and parasitism must be kept to a sufficiently low level. Cheaters and 'goodies' all know this.

That our western civilization morality tends to align with the interests of large-scale cooperative systems is probably no accident. I limit this to western cause I have no clue about any other cultures and I don't want to make an ass of myself.

Of course, this in itself says nothing about the goodness of the system. Cheating a bad system is always an interesting thought experiment. Breaking bad systems and replacing with a new, better one often requires a great degree of 'cheating'. All sorts of interesting things here.

<comment><USER24> I think this is a complex and naunced issue. I have a number of thoughts on your arguments.

Society doesn't set up rules and systems, they seem to emerge as a consequence of beneficial cooperative behavior towards a 'goal'. When it's no longer beneficial to cooperate towards a goal, over say other strategies like cheating, the rules are overlooked, passed, or changed as quickly as they emerged. The prevalence of War as a way to 'rebalance' resources comes to mind immediately, but so too does the reality that only 2% of people pay use taxes.

To your point about parasitism. Human societies are always in a state of change with respect to sociological and technological concerns, and the success of a society in achieving its 'goals' seems largely dependent on how well it adapts to this change. The parasitism you've described seems to be more a reality of economics than society in general, and though your point seems valid on its face, You wouldn't say that the success companies like Uber, which are cheating parasites by your definition, is really a net negative for the society.

to your point about morality. I believe morality is really orthogonal to this issue and should be considered from different viewpoints in different contexts because humans can hold contradictory points of view and still remain 'functioning'. History holds many examples of individuals who challenge what is 'moral' in a society through cheating, and they are sometimes lauded, sometimes not. I think of the narrative surrounding Rosa Parks on one side ( in support of cheating ) and the story of Cincinnatus ( in support of not cheating ) when considering morality in the context of the cooperation cheating dichotomy.

and you're right, this is a very interesting topic, definitely outside the scope of this small classroom experiment.

<comment><USER25> I think we're really agreeing on your first point, and really just have a difference in choice of language. I was kind of sloppy, and used society as kind of a shorthand for the type of emergence you describe. In fact, I would go as far to say that a given society is the very type of emergent phenomena that you describe, and exists as a kind of a high (perhaps highest?) level system that we tend to exist and work within.

Regarding the second point, I really tried to cover this angle with my little bit about 'goodness' of a system, and also vastly over simplified things. Obviously different people in a system are effected by it to different extents, and can play vastly different roles. Many of the statements I was making were with regard to systems with all members are on roughly the same footing. Imagine an honour system for paying for soda, an agreement that everyone on a street clears their own segment of sidewalk of snow, that type of thing. My assumption was that systems and agreements where everyone is more or less on the same footing are generally beneficial to everyone.

Obviously, the situation with regards to taxis and Uber is different. The majority of people are just consumers. They don't really care as long as they are provided the same benefit (reasonably priced, safe, quick, point to point transport). The taxi companies on the other hand are in a completely different position, and in fact, from their position, Uber is definitely a cheating parasite, and a net negative for the taxi companies. I think this falls under my lazy little blurb regarding 'breaking bad systems'.

</comment></comment></comment></comment><comment><USER26> So is the article title another experiment in Behavioral Ecology?

</comment><comment><USER27> The most accurate measurement of what a person has learned over a period of time is their ability at which they are generally able to discuss a subject. The best exam would be a personal exam in which the teacher orally administers a series of generalized questions and explorers the subject matter with each student to understand their actual level of understanding.

While it would take a long time to administer these tests for every student it would provide a lot of value for many subjects, while a written test would still be important to determine particular skill sets for certain subjects like math.

Any average student can jam a notecard full of likely facts or cram facts into their head the night before an exam, without learning much. Likewise working as a team to generate the best answer can allow people to receive a high grade without knowing much.

There is also the fact that even a well read student with a good understanding of the subject matter can a fail a test because they don't have a the particular points asked on the test.

<comment><USER28> I like this approach as well (in theory) and only have some "anecdotal" experience - if you can call it that.

My family originated from East Europe and as such most of my family elders have an old school Soviet experience in education. Consequently they have little knowledge and no experience when it comes to modern-day Western education infrastructure. For instance, my parents were genuinely surprised to hear that I wrote written exams and submitted them only to be reviewed at face value - which is the experience of nearly all undergrads I expect. Their experience was that, even in a "straight-forward" subject like Mathematics, they had to first submit a written response to a problem set in an examination type settings - and then upon completion they would have to explain their solution and approach one-on-one with a faculty member who would only then submit a grade.

Obviously this was done to weed out the cheaters who couldn't explain why they had to correct answers to all the questions. But the result can't be ignored that one-on-one oral examinations, while not exactly pragmatic, are very effective!

</comment></comment><comment><USER29> It should be fair to note that experiments like this can only work in small groups. In much larger class sizes chaos will ensue.

It will also be an interesting experiment to take a large group of students, split them into groups, and then give out exams to each group. By adding a factor of competitiveness test scores might even go higher. Competition is everywhere in nature.

<comment><USER30> I spent some of my highschool years in a differnt country in boarding school and grades and class rank where constantly posted for everyone to see It brought out a real competitive spirit in me and in the whole class and maybe a little shame for the the people at the bottom of the list . I thought It was a very effective tool in keeping the class as whole engaged but that type of thing would never be allowed in the US for multitude of reasons.

<comment><USER29> The reason that class ranking is not prevalent in US is because of publicly shaming the students who are not doing as well as the other.

This can be mitigated if students are working in groups, and group scores are posted instead of individual scores. This way, a group who is scoring low can help and inspire each other to do well and share the pain (shame)

<comment><USER31> In American public schools, class ranking leads to public shaming of the students who _are_ doing well...

<comment><USER32> Depends on the school. At the public high school I attended --several years on various top 100 lists and top 10 in the state-- class ranking was most definitely a shaming of the "weird" minority of kids who were taking "normal" classes. These normal classes were on a completely different scoring tier that ensured the students taking them could not even break the 50th percentile. And coming from Texas, where getting into the top 10 percent of your graduating class is an automatic ticket to any state university, the competition was most definitely fierce.

</comment></comment></comment></comment></comment><comment><USER21> I'm a big fan of unusual approaches to testing, good as I was at the conventional kind.

In high school astronomy, we could bring in a few pages of notes. I once wrote out the notes in great detail, FORGOT THEM AT HOME, and got the highest score on the test.

In college I learned a lot studying for tests, both multiple choice (geology) and essay (history), where the questions were highly predictable.

I love the test Hilary Putnam announced the first day of every class:

Part 1: Write a suitable question for this class. Part 2: Answer it. You will be graded on both parts.

(Note: The recursive answer of giving him his own question back turns out to be infinitely long.)

I once gave an open book test, saying exam questions would be chosen only from problems I'd assigned for homework. Students still did badly. (Ouch.)

</comment><comment><USER33> I saw this on a Naruto episode first (<http://www.hulu.com/watch/36407#i0,p20,s1,d0>), about 6 months before I started college.

For those who don't want to watch the episode, it's a written exam ninja trainees (genin) need to take to be promoted to ninja squad leader (chuunin). Any team (of 3) that has a single member fail will be failed as a group. If any ninja gets caught cheating they will be given a warning, and after three warnings they will be failed.

 _SPOILER (no really, the episode is great in this context even if you don't like/watch anime much)_ The intelligent (but not book-smart) notice the leniency of the anti-cheating-system and the carefully worded instructions to "not get caught", and then find ways to obtain answers from "sources", qualified chuunin who were intentionally planted in the exam hall who knew the answers, or to collaborate with teammates. _End plot summary_

I think it's important to teach kids not just _the_ answers to problems posed, but also ways to _find_ them. If it's too easy for them to find answers without rigid rules, it probably means that he problems we are posing them are not hard or thought-provoking enough in the first place.

Edited for a missed phrase

<comment><USER34> Interestingly this is the only episode of Naruto I've ever seen. I remember being quite impressed at how cerebral it was, as I was expecting to see a bunch of ninjas running around slicing off each other's heads.

</comment></comment><comment><USER35> This is a completely idiotic way of testing people. I could have come into class not knowing anything, waited till the end of the test and then offered 100 dollars to anyone to be allowed to copy their whole test. And I would have passed the class?

It kinda reminds me of CS-whores. The one or two CS girls in each graduation class that regularly used sex-appeal/flirtation to get CS guys to do their homework (very successfully too!).

At some point your no longer testing people's knowledge and creative thinking, but their social skills and ability to manipulate others (and maybe their breast size/size of their 6 pack).

I feel like the professor treated this like a sick little game and enjoyed himself while doing it.

At the end of the day you are competing against your peers either through a curve, or through your raw grades because you're all going into the same fields and are competing for the same jobs with your GPAs. Making a system where cut-throat behavior is encouraged and putting down your pays off is really sad.

<comment><USER36> I completely disagree. I found this to be an excellent example of real world training. I worked through college in IT and from that job on, working in the real world was exactly like this. We worked on projects with teams of people. We looked for the best possible solutions to every problem we faced. Even when working alone on something, you had your peers as resources. You weren't locked in a closet coding on a computer, offline, without access to books or other tools. That's what test taking was like for me.

Some people, like me, are experiential learners. Others find their best thoughts through discussion and the evolution of ideas. I would have loved to have taken many classes like this. Fortunately, that's what the real world has been like for me - being a member or leading a team to produce the best product we can, either as a team, department or company. As you called it my "pay off" is education. I found mine through methods like this. Not through memorizing facts and methods just to pass a test.

<comment><USER35> While I agree that the process is more similar to the "real world" - <USER2> fundamental problem is that the grading is not. When you work as a team towards some goal whoever is evaluating you is doing so based on your contribution to the team.

Here the fundamental scoring method is still the test, so an individual's motivation is to do better for himself; the teams success is secondary (and if the test is curved it may be non existent). Free riders aren't punished or penalized and all sorts of outside influences come in where people start trading on money/sex/favors/friendships/etc.

Arguably those outside influences exist in the real world, but why create a system that explicitly has no mechanisms to counteract them? (ie. the prof says you can do anything that is legal and doesn't try to catch "cheaters")

</comment></comment></comment><comment><USER37> Too bad no one tried to sabotage the consensus answers. You could get responsibility for writing one of the group answers, write it wrong, then turn in your own test with it correct. Inject false data into discussions, etc.. It isn't really game theory without some interesting gains and loses due to cooperation or deception.

</comment><comment><USER38> Actually this is not cheating. Cheating means copying somebody's content with or without his permission in an exam where this kind of information sharing is forbidden.

In here, the lecturer specifies that information sharing is not forbidden. Therefore technically this is not "cheating". But it is wonderful to see when you remove the outside limiting factors and let the phenomena occurs in its own volition. Probably this will be one of the courses the participant students will never forget, instead of courses where you "memorize" everything until the last exam.

Kudos to Mr. Nonacs.

</comment><comment><USER39> I wonder if this was being graded on a curve. If so, an interesting strategy would have been to sabotage the group effort while secretly preparing a "lone wolf" answer. The saboteur could continually steer the conversation in the wrong direction and possibly even alter the group answer to something absurd before it was turned in.

Or if he wanted to concentrate on his own work, he could bring some headphones to tune out the horrendous noise coming from outside the classroom where his friends happen to be practicing for their upcoming rock gig.

</comment><comment><USER40> This reminds me of a slightly, although not entirely, related paper that I read a while ago titled "Embracing the Kobayashi Maru – Why You Should Teach Your Students to Cheat". I've linked to it in this item: <https://news.ycombinator.com/item?id=5609346> because I think it is different enough to warrant a separate discussion.

</comment><comment><USER41> A collaborative assignment is a really solid education tool.

What's missing is an explanation of why the author thinks this led to an objective evaluation of what individual students learned _before_ test day (if he does indeed think that). That is the point of an exam. Imagine if med students could collaborate on their boards. It would pretty well invalidate the purpose.

</comment><comment><USER24> This would have been more interesting to me as a study in game theory, if some of the 'mob' had given false or incomplete answers to the rest of the group on a minority of the questions, saving the 'fully-correct' answers for themselves. That way, if there was a curve they would benefit totally from the 'mob' and still come out ahead of it.

<comment><USER42> Surely one of the main points of the exercise was that, precisely because there _wasn't_ a curve, whole-class cooperation can result in everyone in the class getting a higher score (20% higher) than they usually would.

Grading on a curve wouldn't be the same game just 'more interesting', it'd be a completely different game, and one that's lost most of the "To win at some games, cooperation is better than competition" aspect.

</comment></comment><comment><USER43> I like this idea, except that I'd be worried about money entering into the scheme. In a real world setting, it's not unreasonable to pay someone to do the work for you, but in a school/learning setting, I dislike the possibility of people paying their way out of the work.

</comment><comment><USER44> Here is what I would like the professor to do. Follow up with a "normal" test and see how the students perform. If the class average was greater that prior year performances, the co-operation actually helped in drilling the concepts in.

</comment><comment><USER45> So really, this was was a class project involving a scenario that superficially resembled cheating on an exam, rather than actually cheating on an exam.

</comment><comment><USER46> You should have had more questions to have more strategy. That was a pretty easy test... You also gave them an easy way out if it was too hard...

</comment><comment><USER47> If you enjoy this kind of thinking, you'll love Dan Ariely's Behavioral Economics class when it next comes to Coursera.

<comment><USER48> Because we'll enjoy cheating on it so much more, or something?</comment></comment>


JSDB.io – A Database of JavaScript Libraries - <AUTHOR> http://www.jsdb.io/?sort=trending

<comment><USER2> It's unfortunate that people still think they need monolithic libraries to get anything done on the client side. The node ecosystem showed this doesn't have to be the case. It becomes even more important on the client side to keep dependencies small.

My favourite ecosystem for client side development these days is component ([https://github.com/component/component](https://github.com/component/component)). It's similar in style to npm but faster and made for building apps from small modular pieces. It has a growing community and lots of modules already ([https://github.com/component/component/wiki/Components](https://github.com/component/component/wiki/Components)).

<comment><USER3> I've had this debate with a friend who's a big proponent of EmberJS (and to a lesser degree Angular). My friend feels that without one of these libraries you will simply be writing way too much unnecessary boilerplate code for a single-page app of significant size. I personally prefer to rely on small modular dependencies, so Component appeals to me, but I've only played with Ember/Angular a little bit so I don't necessarily know what I'm missing. Can you recommend a set of Components that would provide similar functionality and productivity?

<comment><USER2> I'm still using backbone.js within our app but a lot of people seem to be using things like:

* [https://github.com/component/view](https://github.com/component/view) for views built on top of reactive for declarative bindings

* [https://github.com/component/model](https://github.com/component/model) for models

* [https://github.com/component/router](https://github.com/component/router) for routing

So what we have so far from these 3 libraries is basically a decomposed backbone with declarative bindings. That will cover 99% of your typical app. I don't find there is too much boilerplate.

<comment><USER3> Take a look at the Ember examples at [http://emberjs.com/](http://emberjs.com/). They're doing a lot more with a lot less code. Backbone had its day, but the world is moving on, and a new project that only offers Backbone-equivalent functionality won't garner much interest from me or probably anyone.

</comment></comment></comment></comment><comment><USER4> My favorite ( though only for jquery plugins ) - [http://www.unheap.com/](http://www.unheap.com/)

<comment><USER5> That site looks clean! Do you know who developed it?

</comment></comment><comment><USER6> Looks great. I've had luck with [http://www.javascriptoo.com/](http://www.javascriptoo.com/) too.

</comment><comment><USER7> Thank you for this. I just discovered [http://fooplugins.com/footable- demos/](http://fooplugins.com/footable-demos/) and it's the perfect alternative to Data Table!

</comment><comment><USER8> [http://jster.net/](http://jster.net/)

</comment><comment><USER9> hovering over ratings: "Overall JSDB.io Rating (derrived from combination of the other metrics)"

So I guess that means the rating are based on some formula of: stars + average time between commit + forks + contributes

My only problem is that doesn't this rating favor larger projects (Angular or Ember) as opposed to smaller projects that are perfect for solving small problems? The only way I can see around that is if stars has an overwhelming weight in the formula.

Anyways, looks helpful none the less (will look though it)

<comment><USER10> Hey! (I made this) Stars _do_ have more rating than the other metrics, which evens things out. Yes, larger libraries like jQuery are rating higher because of the ranking system, but thats actually accurate if you are looking at 'popularity'; furthermore, there are only a few projects that are on this scale.

Try 'trending' if you want to see libraries that are growing quickly.

</comment></comment><comment><USER11> Would be great if all the packages on Bower were presented like this.

<comment><USER10> Potentially each item could have a bower package name or endpoint that you can copy and paste into terminal?

<comment><AUTHOR> That sounds great, would definitely save some time.

</comment></comment></comment><comment><USER12> What's the calculation for the ratings? Also would be great if there are sorting options.

Otherwise this is really great!

<comment><USER10> three sorting options: recent, popular, trending. What kind of sorting were you looking for?

<comment><USER13> It struck me, while browsing that, I would like to be able to browse the libraries by excluding known types.

Things like "Show me all the things that are not frameworks or jQuery plugins"

I'm not looking for anything in particular, but it would nice to see the possibilities without having to search through things that I know I'm not looking for today.

<comment><USER10> Right, what you are looking for is advanced filtering options. Definitely something thats desirable, albeit hard to pull off for a side project ;)

</comment></comment></comment></comment><comment><USER14> Similar database of jquery plugins [http://jquer.in/](http://jquer.in/)

</comment><comment><USER15> Looks like 531 libraries are in this list as of now.

</comment><comment><USER16> Confusing name. It's not a db engine built with javascript.

<comment><USER4> Is imdb a new NoSQL database?

<comment><USER16> is im a programming language ?

<comment><USER4> Give me one example of a database with a programming language ( or its abbreviation ) in its name? "im" could stand for in-memory.

<comment><USER16> javadb.</comment></comment></comment></comment></comment>


Why cyclists should be able to roll through stop signs, ride through red lights - <AUTHOR> http://www.vox.com/2014/5/9/5691098/why-cyclists-should-be-able-to-roll-through-stop-signs-and-ride <comment><USER2> Although the article alluded to studies that show this approach is safer it didn't bother to cite any. Here's one based on results when the law passed in Iowa: [http://docplayer.net/1126976-Meggs-jason-n-stops-harm- bikes-...](http://docplayer.net/1126976-Meggs-jason-n-stops-harm-bikes- page-1-of-15-title-page.html)

Slowing down as you approach the stop sign, scanning the full 360 degrees around the intersection (which, unlike cars, cyclists are able to do easily and quickly), being prepared to stop if necessary, but continuing on through if there's no reason to do so, is perfectly safe.

I'd make the analogy thusly: as a cyclist coming to a stop sign, I've got to come to a stop, get off my seat and set foot on the ground, remount, then get going again from a standstill. When you're doing this every few blocks--which is not at all uncommon when biking in the city--it gets extremely frustrating. As a car driver, imagine if you had to come to a complete stop at a stop sign, turn off the ignition, then restart the car and continue on your way. It feels like the same thing. (edit: used more clear terminology)

<comment><USER3> When I drive (which is a lot less than I bike), I drive a stick, and at least at reds, I put the car in neutral and engage the parking brake so I can rest my feet, which (except for the loss of momentum) is comparable to the trouble incurred in dismounting for a bike.

In general, driving or biking, I think we should stop trying to decrease effort, and increase it instead. It's good for you. As a cyclist you get stronger, faster, more skilled. As a driver, you get more skilled and are forced to stay more alert. All of these things make you and everyone around you safer, so savor and put as much of yourself as possible into your cycling and driving, for everyone's sake. You don't get good at things you don't do.

</comment></comment><comment><USER4> As a cyclist of 40 years who's (hopefully) learned from their mistakes, I strongly disagree. Not only is it unsafe, pisses-off drivers and pedestrians, gives cyclists a bad name, but it's also completely unnecessary because you'll easily catch-up with cyclists who shot the lights at the next intersection anyway without even trying. That's what cyclists who shoot lights don't get is that it's actually not any faster in the long run. Having said that, I suspect that many drivers who are pissed-off by cyclists shooting lights would be the ones doing it themselves if they were on bikes because it's really just a form of road-rage. Yes, some cyclists are stupidly aggressive, but so are many drivers.

<comment><USER5> I am surprised to hear you assert that there is no time saving to be had in running red lights.

In my opinion it's just too bad for annoyed drivers. They are welcome to join us.

What angry drivers usually don't get is that the equation is much different for cyclists. Our capacity to cause harm is a tiny fraction of that of a car. Also, we can't get tickets that raise our car insurance premium. Wheeeee!!!

<comment><USER6> "Our capacity to cause harm is a tiny fraction of that of a car."

By rolling lights/stops you're making it harder for cars to notice and avoid you, making it more dangerous for yourself. I hope you don't find out that truth, though.

<comment><USER5> I appreciate what seems to be a sincere sentiment, but at the same time I don't feel like it's my place to point out to a stranger that her, say, sedentary lifestyle or drinking habit is a health risk.

</comment></comment></comment></comment><comment><USER7> Always used to see a guy cycling on my commute home. He'd roll through every stop sign and most traffic signals. (He explained one day that it "saved energy" for him to keep going...even though he cycled as "exercise...")

I don't see him anymore. One day last year, he rolled through a red light in Koreatown, right into a truck which had the right of way. He was thrown from his bike about 20 feet and died from blunt force trauma and/or internal bleeding by the time paramedics arrived.

<comment><USER8> That's a sad anecdote. It doesn't seem to address the argument or actual safety data presented in the article.

<comment><USER9> It's a data point and was used as such. The effects of breaking moving vehicle laws can be rationalized away when the mass of the vehicle moving is low. That doesn't preclude other incidences, such as this one, where someone who's job it is to drive a truck has to wrangle with the fact they killed someone. They guy who died could give two shits about the situation.

I saw a cyclist roll through a pedestrian crossing with people in it on his side of the road at the intersection at the end of my street. I rolled up to him in my car at the next light and told him he was breaking the law. He asked "but is it safe?". The implication is, with this leading question, is that he thought it was safe to do. What he didn't observe was the car behind him not slowing down for the pedestrians because they were watching him.

Stopping at a crosswalk, or yielding right of way, is an important rule because it gives VISUAL indicators to other drivers of nearby vehicles. It's a backup mechanism for safety at times. Rationalizing laws don't apply to oneself because they cause delay do not include the fact it the action may also be the difference between life and death - for someone else. Are we really going to rationalize away the fact driver may float lights more if they see bikes doing it as well?

The way Davis, CA handles this is to install special lights for bikes. I would assume they thought through it and decided floating lights is bad.

For the last 4 years, up until a few months ago, I had been riding at least 5-6 hours a day on fairly busy roads. I've seen a lot of shit that people do as a result of other's actions, including bikes, and I do NOT think bikes should be precluded from obeying traffic laws, especially when the only point to it might be to speed up a bike commute or "save energy". Whatever that means.

<comment><USER10> Here's an explanation from a physics professor (cited in the original article) that might help explain what "save energy" means. [http://nacto.org/wp- content/uploads/2012/06/Fajans-J.-and-M....](http://nacto.org/wp- content/uploads/2012/06/Fajans-J.-and-M.-Curry.-2001..pdf)

In case you can't be bothered to read this either:

> He also calculated that a cyclist who rolls through a stop at five miles per > hour instead of stopping fully needs to use 25 percent less energy to get > back to full speed.

<comment><USER9> > In case you can't be bothered to read this either:

My entire comment was based on someone else's comment in these threads, not the article.

And, not that I give a shit what you think, I actually did read the article and don't have to agree with it regardless of whether I "bothered" or not.

</comment></comment></comment></comment></comment><comment><USER11> After having spent a ridiculous amount of time on a bike recently, I now believe the difference is perceptional. When you drive you are in a glassed in box. The glass has no anti-reflective coating so you see a lot of moving reflections. This makes peripheral vision mostly useless. You have blind spots that you have to move your head to overcome. Your line of sight is lower to the ground. You can't hear anything outside the car unless you have your window down and then probably not either. You can't talk to anyone, the best you can do is honk your horn in an slow speed possible collision situation.

So compared to a cyclist/pedestrian a driver is deaf, dumb and partially blind. So it makes perfect sense that cars have to stop and other transportation modes do not.

This disparity becomes quite poignant when someone in a car stops to let a cyclist/pedestrian cross the street when they actually have the right of way. They are expecting the cyclist/pedestrian to trust their life to the judgment of someone who is quite isolated from the environment.

</comment><comment><USER12> Cyclist commuter here. Red lights should be red lights to everybody.

However, Idaho stops are the way future. It's just doesn't make sense to apply the same "come to a complete stop" standard to cyclists. They're traveling at a much lower speed and have much less ability to accelerate. The extra time it takes to come to a complete stop (which means finding your balance at a stand still), and then remounting the bike accelerating through the intersection is not worth it, and makes the commute that much more of a slog.

I think characterizing the Idaho stop as "rolling through the intersection" might be a little bit misleading, since it conveys a really lax attitude. Idaho stops are generally quite safe.

Edit: In most cases, Idaho stops have very similar cadence to a car coming to a full stop. You slow down up to the line, look all around you, determine the right of way, and if you have it, you start peddling back up to cruising speed. The fact you don't come to a complete stop is pretty much a technicality because the timing is almost the same.

If you come to a complete stop, the timing is all off, and there's much more likely to be hesitation and ambiguity. Starting from a stop takes a lot more time, is much more likely to lead to false-starts, and puts you in a very vulnerable position.

<comment><USER13> Any advice for bicycle commuters approaching a red light on a rarely-used side road that is triggered entirely by a weight sensor? I took your advice once ('red lights are red for everybody') and sat their for 5 minutes waiting until another car pulled up to trigger to weight sensor and the light changed in seconds.

Now I just go. I treat that particular red light like a stop sign. I don't lose any sleep over it. And most cops where I live are pretty forgiving to bicyclists.

<comment><USER12> Clearly there are exceptions. In my area, I don't come across lights that use sensors (or at least the sensors pick up cyclists).

I'm just uneasy with saying "red lights = stop signs for bicyclists". In complicated intersections, you need to wait for the green, unless it's very obvious there's no oncoming traffic.

</comment></comment></comment><comment><USER14> Seems like TFA is an opinion piece and cites no research on actual safety. It alludes to one reason this is good: getting the cyclist out of the intersection, and therefore greater danger, sooner. Another good reason might be to make cyclists' behavior more predictable. As is, you never know which type of rider you are going to get, so you can't make assumptions.

I think an actually safer thing to do would be to give cyclists the right of way. Then drivers could at least take for granted that cyclists are going to not stop for red lights or stop signs.

<comment><USER15> One aspect of safety which wasn't mentioned in the article is the moment when lights turn green and cars and bikes begin to move forward. There's a noticeable tendency for some riders to want to stay in front of the cars and this engenders an equally fierce desire in the drivers to overtake said cyclists. Road rage is almost unavoidable at this point.

I usually stop behind the lead car at traffic lights to avoid this; I can usually keep pace with cars (in London) but flaunting this by trying to race them away from the lights is just asking for trouble, not to mention more physically taxing.

So... if I'm on the front of a queue and can safely move away before the lights turn green, I'll do it because it puts distance between myself and the lead car, giving the driver more time to line up a safe manoeuvre around me once the traffic starts moving.

This has to be weighed up against the very real danger that the drivers will be fuming with rage at the arrogant cyclist in front and thus losing the senses of calm and serenity that I'm trying to spread :-)

<comment><USER16> IME drivers fume with rage no matter what I do. They'll shout abuse at me as they pass even if I'm in a bike lane, completely out of their way.

<comment><USER14> I agree it's a real problem. I mean it's important to remember that not every driver is an asshole, just like not every cyclist is a crazy law breaker, but there is enough of a critical mass of both to make sharing the road really dangerous, and cyclists come out worse out of it because physics.

Ideally, I think larger cities could do well with removing the ability to drive cars there without some hefty taxes/tolls and instead provide moving walkways and better public transit. Then cycling becomes much safer and a better option.

I've also had the idea to run a "shower truck" some place like NYC: basically park it in front of an office building between 8 and 9am and for $1/minute you get to shower in there. Lack of showers has always been the reason I didn't commute by bike.

</comment></comment></comment></comment><comment><USER17> This is a half measure. What cyclists need is access to limited access, pedestrian free, well maintained roadways.

[https://mitpress.mit.edu/books/effective- cycling-0](https://mitpress.mit.edu/books/effective-cycling-0)

<comment><USER18> I haven't read the book, but second the sentiment.

Few death traps on my commute take more time and energy than any lights. The one spot where old railway was transformed into bike lane is sweet. You can travel half the city without constantly worrying about dying.

</comment></comment><comment><USER19> "... Oftentimes, they don't trigger traffic lights to change, because many run on inductive sensors buried in the road (the reason for all the "Dead Red" laws in the map above)."

This drove me crazy when I lived in Seattle. Many of their lights would never turn. So I would have to get off my bike, walk over and press the button. Now that I live in NYC, Idaho stops are the norm where nearly everybody, including the casual cyclist does it and tickets are few and far between, it not only takes my commute from 15 minutes to (literally) 4 minutes, but I feel safer because I'll usually leave a huge pile of traffic behind me with a clear road around me for blocks since they stop at every light and I don't.

Of course, NYC has a 25mph city-wide speed limit, so that helps dramatically.

I think the most important thing here is being obsessive about looking for cars and yielding appropriately. If you fail to do that and are a daredevil who just blindly runs out into traffic, which I see fairly regularly, you are putting your life at risk and potentially others around you as well.

Edit: Looks like Seattle just passed a dead-red law last year! Now if they would just classify electric skateboards as bicycles like California did, that would be spectacular.

</comment><comment><USER20> One thing I find frustrating about driving in the US is that stop signs are everywhere! Even on a fully open junction in a quiet suburb where you can see a good few hundred feet down the road, you still have to stop. I know it's the law, but why?

In the UK you don't have to stop at every junction, if the junction is open (i.e. you can see traffic clearly) and it's clear you can go on through without stopping. If the junction is closed (i.e. you can't see oncoming/cross traffic) then you must stop, and get a good visual before pulling out.

As a result of this cyclists in the UK already don't stop at junctions because, unless its a closed junction, no one has to stop if it's clear.

I'm pretty sure in the US you can crawl right on a right light if it's clear so what's the difference in letting a cyclist carefully go through a stop sign or red light?

<comment><USER21> You have to come to a complete stop at the red light before you can turn right

<comment><USER20> Ok, that seems sensible if it's on a red. Basically treat it like a closed junction

</comment></comment></comment><comment><USER22> How about no. Stop signs were designed to prevent people being hit by crossing traffic.

This isn't just a to protect the cyclists from being hit by cars, but to protect pedestrians from being hit by cyclists.

I'm sorry but my experience of living in London in the past 4 years pretty much made me hate cyclists with passion.

I find them considerably more dangerous and pesky than cars, they simply ignore all rules whether it's not giving a flying duck about the red signal at a bike lane while pedestrians have the green light to cross the street, utterly ignoring no bikes allowed in the run/walk only paths in Hyde Park or by interchanging road, bike lane, sidewalk and even the crosswalk at will with nill consideration to pedestrians and a shitty attitude to boot.

I'm constantly buzzed off green lights (to me) by cyclists that cycle at high speeds because they could not be arsed to honor a red light, I've been hit by bikes more than once in these 4 years, and just over the weekend I've seen a guy on a rental metro bike hit a baby carriage (empty one as far as i could tell) in Hyde Park because they were in a no-bike zone and came out a turn which has no visibility whatsoever.

I really don't understand the level of self entitlement that cyclists seem to have and why they seem to have such a shitty attitude towards drivers and pedestrians alike. A bicycle rolling through a stop sign isn't any less dangerous than a car rolling through one, if anything a car is easier to spot than a bicycle and cars don't tend to have their visibility shuttered by driving between full lanes.

The reason why most countries do not allow roll through stop signs or at least heavily restrict them is that rolling through a stop sign sets the wrong behaviour pattern because once you get used to a stop sign you know you can roll over you aren't going to slow down to roll over speed you might simply slow down by a bit but not nearly enough to respond appropriately.

The same thing is going to happen to cyclists they'll get use to it and eventually get careless they won't give 2 ducks about the padestrians trying to cross the road with already ludicrously short light times and they'll take more and more risks as far as crossing the intersection goes.

Cyclists don't have mandatory insurance, they can hit anyone and do pretty hefty damage if it's at speed and good luck suing them for anything at least with cars in most countries you can always sue the insurance of the offending driver. Heck at this point I'm not even entirely sure if being hit by a bicycle in the UK constitutes a "road accident" so they might as well just take off and not give a flying duck about it, it happened to me got hit in the side I assume by the stem/handlebars at pretty high speed the cyclist didn't seem to give a shit at all and just wobbled a bit and continued on his way without even checking. It was a sharp pain but not bad enough however the night after half my side was purple if it would be a bit stronger or sharper hit I might've ended up pissing blood for 2 weeks.

<comment><USER23> Agreed 100%.

I live in London too. As a pedestrian, irresponsible cyclists have really pissed me off to no end.

Many cyclists have an attitude of entitledness, which makes them a great danger to the rest of us pedestrians.

Not all cyclists are like this mind you, but it's enough of a population that I second-guess most cyclists wil follow rules of the road.

To put into perspective - when you're driving and you have a green light, you generally assume cars approaching the red light orthogonally will slow down and respect the stop signal. Now imagine the situation where you cannot assume this and at every intersection you go through, you assume a car will ignore their traffic light. That's what it feels like to be a pedestrian around cyclists in London.

Quite too often cyclists will plow through zebra crossings (crosswalks for you USA folks, where pedestrians have full right of way). Even if you're in the middle already.

A cyclist once came at full speed within inches of my daughter's pushchair (stroller) when we were in the middle of the zebra crossing, and when I loudly said "what the heck" at the guy. He turned back and screamed very loudly "Fuck You", in front of my daughter.

Similarly just the other day a cyclist came through a zebra crossing at full speed about a foot away from me. I again said "what the heck" and he responded loudly "oh, Fuck Off".

A few intersections have cyclists that regularly come through when pedestrians have the green man signal.

It's pretty ridiculous.

<comment><USER24> > Many cyclists have an attitude of entitledness, which makes them a great > danger to the rest of us pedestrians.

Isn't the reasoning for the proposal that allowing bikes this special treatment of stop signs and red lights would incite them to use the road instead switching to the sidewalk (to be faster)? I.e., yes, bikers might be entitled, but the suggestion would also benefit pedestrians.

<comment><USER25> In the UK (where I think the poster is from), it's already illegal for cyclists to cycle on a pavement (sidewalk) next to a road. I think.

His experiences are with cyclists flouting the existing laws when they travel on the road.

<comment><USER13> In my city (not-UK), it is only allowed if you are moving at the speed of pedestrian traffic (a limit of 8mph). I'm guessing to allow children to ride without fear of being cited, or allow a cyclist around a difficult road condition.

My point is that I do not know of anywhere that a cyclist can hop on a sidewalk at full-speed and not be violating the law.

</comment></comment></comment></comment></comment><comment><USER26> > Drivers might be angrily remembering the last biker they saw flout the law, > wondering when traffic police will finally crack down and assign some > tickets.

How about the laws where drivers have to maintain a minimum distance from cyclists? If I ever see _that_ law enforced, I might start giving a shit about other traffic laws. Running lights allows me to get a head start on traffic and hopefully get to the _next_ light/stop sign before drivers try to murder me by passing within inches so they can stop 100 feet away a few seconds sooner.

<comment><USER13> I had someone do this me between stop signs and then he had to slam on his brakes since he barely had time to get around me. I then proceeded to follow him for the next few blocks because a car isn't that much faster than a bike in these situations.

People in cars hate being slowed down. Some, I hear, even get violent. There is a patience I learned moving through my city at 15 mph. I wish more people appreciated it.

</comment></comment><comment><USER27> I'm curious about what Germans think of this, since people look a pedestrian askance if you don't wait for the light.

As an occasional cyclist I'm of two minds. On the one hand, having too many stop signs along a roadway gets annoying so mentally one wants to simply slow down and look and if no cars have the right of way at the time, go through. The danger is that this behavior gets modified to a default of riding through and only slowing down if a motorist doesn't give you right of way (slow down or wave on) and assuming that as a cyclist I have the primary right of way (weaving through pedestrians and cars) in other words wishing people and cars did not have to share (yes, it's only a mindset, but one easy to allow to set in).

Also, since cycling is healthy, you get even more exercise by stopping and starting constantly so from a health perspective it's better as it improves your workout and keeps you alive by preventing unnecessay collisions.

<comment><USER28> In Germany you can lose your driver's license quickly if you ignore red lights as a cyclists. It's enforced a lot, especially in cities with a high percentage of cyclists. And you'll get frequent comments by others, but even more as a pedestrian than as a cyclist.

<comment><USER27> I wish we had something like that for cyclists who flout red lights. It's too common where I live. And I know the allure, as a part time cyclist, I understand it but a disincentive is good too.

</comment></comment></comment><comment><USER29> While driving & cycling, I observed that most cars here in Quebec pass through stops at speeds ranging from 15 to 30 km/h by doing what we call an american- stop in Quebec-slang ("stop américain"). I suppose this also happens in the US.

In a car, 15-30 km/h feels like you are really close to be completely stopped. It turns out that these speeds are pretty much the average cyclist speed range. (Cyclists may appear to go faster because they are smaller, just like trains look like they are slower than they really are).

I guess most frustrated car drivers don't realize they are also "breaking the law" at stops. I can only recommend they start cycling, the endorphins would calm them.

</comment><comment><USER30> OK, maybe the article is right and cyclists should be able to do Idaho stops. I'm open to allowing this if the available data says it's safer for everyone.

What I can't accept is some cyclists following the law and others not. Either everyone should do Idaho stops, or no one should. What settles that is the current law.

Are Idaho stops legal for cyclists where you live? No? Then until the law is changed they are not an option, period.

</comment><comment><USER31> Whenever someone yells at me for doing this i just tell them, "it's pareto efficient" Of course, i slow down and make sure there are no cars or people in the way before crossing.

</comment><comment><USER32> The cop who gives you a ticket probably doesn't care about your Vox articles, Maclolm-Gladwell-grade pseudo statistics, or these comments.

At least in the Bay Area, cops are definitely willing to take the time to ticket cyclists. In Los Gatos where I live, the police will sometimes take a Saturday and just watch a busy intersection and literally ticket EVERY cyclist who blows through.

Of course we have also had a few cycling fatalities here, always the same story:cyclists blowing through intersections.

Don't do it. Don't be the asshole who makes life more difficult for other cyclists. No one cares about your bogus statistical arguments.

</comment><comment><USER33> I don't see how it's safe to allow this for bikes, but it's not safe for cars? Why not just allowing everyone to "slow down and look for traffic" and then decide if it's safe to go through or not? That's basically what you do when there's no traffic lights and if people really slow down and look there will be rarely any problems with that. That's how roundabouts function, and they are generally very safe.

<comment><USER34> As discussed in the article, cars have worse field of vision, drive faster, and cause significantly more damage when they mis-judge whether it's safe to proceed.

</comment></comment><comment><USER35> TL;DR; Why? Because we should encourage natural selection in humans. Only the fittest cyclists survive :)

</comment><comment><USER3> Yeah and no. Cyclists should not roll through anything until they've completely scanned the intersecting traffic, which usually requires stopping briefly (but may not, for intersections with good visiblity and low information density and riders who are good at holding a line at slow speeds -- exercise good judgment). You put your life in the hands of others whenever you enter an area you did not already successfully vet for the absence of opposing traffic.

But, waiting for a red when there's no traffic is pointless. Also, there can be a lot of danger for cyclists, especially novices, when the light turns green, due to aggressive motor vehicles, so going through a traffic-free red can even be safer.

While you can argue that the same logic applies to cars, the potential for confusion/abuse and the fact that cars weigh much more factors against allowing cars to follow the same rule. So, when cycling:

Treat stop signs as stop signs (NOT yields), and treat red lights as stop signs (NOT yields). Come to a _complete_ stop, scan, and if there's no traffic in either direction, continue. Completely safe, but you save waiting for a red light to turn when there's actually no traffic spooled up.

(Don't forget to look both ways even on one way streets. If you run a red and get hit by a salmoner[1] you can't really complain, can you?)

Get over the dismounting thing. Going through reds is about saving time waiting for it to turn to green, not about saving time dismounting. A good city rider should be really good at dis/remounting seamlessly, as well as being able to ride at crawling speed without having to stop or swerve.

Try to get over the momentum thing too at least for a while. You'll become a stronger faster more skilled cyclist this way anyway, and there's nothing more pleasing than not just being /faster/ than a cab, but actually /accelerating/ more quickly than a cab despite all their cylinders and horsepower, and it's going to take a lot of stop and go practice to get you there, so don't slack on this. If you're using clipless this goes double -- you need to get really good at unclipping/reclipping so the worst thing you can do when you start is to jealously guard your momentum and never put your foot down.

Again, the key is, never go through an intersection that you haven't already gotten total visibility into. Whether this lines up with signal phases or not is irrelevant. You can get run over by a misbehaving road user when you have a green too, and you should beware then as well, treating greens as (very soft) yields, especially in intersections with poor visibility or high information density (eg in Manhattan, crossing an avenue while going crosstown)

And of course, I'm human, so I don't always practice what I preach. I often regret that later and wish I had.

[1] salmoner: slang for road user going the wrong way down a one way street (usually but not always a cyclist -- I observe that NYPD patrol cars also often do it, usually just because they can (no sirens) but sometimes to get to an emergency (sirens))</comment>


Ask HN: Why isn't a content addressable cache built into the Internet? - <AUTHOR>

I have a simple internet protocol in mind. Does it already exist? If not, why not?
The idea is that there should be a content-addressable request protocol. By presenting a (20 byte) hash the server responds with a chunk of data (say, 2M in size) which is associate with that hash. If a publisher (NetFlix) were to offer their content using this protocol, they would transmit to each authorized viewer, a list of 500 hashes for a 1 GB movie (total size of hash list - 10K).  The client then requests each chunk by hash key in order to stream a movie.
Any ISP (Comcast, Level 3) seeing this protocol coming over their network, realizes that they can service a chunk request by returning the cached data, instead of forwarding it upstream to the source to fetch it over and over again. Routers could incorporate the protocol into their stack, so they can short-circuit high volume chunk requests out of a local cache (from several gigabytes to terrabytes). Once an ISP has the chunk data, they can serve it 1,000 times without requesting it from the origin server.  They can manage their cache purely based on demand for each chunk.
With this protocol widely in place, I think it would be possible for 100M households to simultaneously watch a movie when it becomes available for download.  I don't think that's possible using the current Internet protocols and CDN's.
Would this not be far superior for the network to transparently handle caching this way, rather than the messy system of CDN's we have today?
Does copyright law or the DMCA make it impossible to operate a system like this? <comment><USER4> I think CCNx is going in this direction. There's also IETF DECADE and the older Internet Backplane Protocol.

IIRC the DMCA has an explicit exemption for caches.

To get ISP caches deployed, you have to convince ISPs that they'll save money. CDNs actually work against you here because they are either free or in some cases paying ISPs, and if an ISP allows CDNs to get close to its POPs then CDNs are just as efficient as ISP-operated caches.

</comment><comment><USER5> I worked at a big streaming media company and there are significant DRM challenges with serving video in a way that protects the content. When you're trying to get serious content deals from producers they will dive into the deepest level of how you handle their content to make sure it meets their own internal standards before agreeing to anything. Companies like BitGravity are developing solutions that meet these requirements. One idea might be to expire the hashes in a 5 minute rolling window which would still give a huge caching advantage to ISPs:

1\. ClientA is authorized with video service. 2\. ClientA gets 50mb of hashes to buffer 3\. ClientA starts downloading hashes sequentially, requesting more hashes from the service as the queue is emptied. 4\. ClientB is authorized with the video service. 5\. ClientB requests same resource and gets same list of hashes. 6\. ISP can cache the hashes for 5 minutes and get some savings for popular content.

I think this would be a very good solution for live broadcast where you're looking at a huge number of people requesting the same content, but for VOD it would have limited return.

<comment><AUTHOR> If you recognize that a hash is _equivalent_ to the content, you realize you have to wrap DRM around the hash lists, just as you would the original content.

Perhaps limiting the cache lifetimes would give some legal protection to network operators. Nobody is sending take-down notices for network caches today, are they? I would love to see this protocol have some legal safe harbor - perhaps based on a limited (24 hour) TTL before requiring refreshing the cache from source (which could just be a "ping" w/o retransmitting the whole chunk).

</comment></comment><comment><USER6> How do you do any sort of security on this? I doubt any copyright holder is going to be happy when anyone with a list of hashes can download their movie. Using most types of encryption is out, so there goes most DRM solutions. Using IP or host based access lists defeats the purpose of the caching system, so that's out as well.

<comment><USER7> Check out CCNx (Content Centric Networking) project from PARC/Xerox leaded by Van Jacobson - the security seems to be baked in the design. Here is an intro: <http://www.slideshare.net/PARCInc/contentbased-security>

<comment><AUTHOR> Why implement something complex, when something simple will do? This cache should be (in my mind), DRM-agnostic. Just put your DRM around your hash lists, just as you would around your original content. DRM can be a layer above the caching layer.

</comment></comment></comment><comment><USER8> It's done manually, when the iPlayer was new there was talk of this being done, that you can rent servers in every exchange. BBC are really relaxed about piracy (in comparison to others) so this might not be common.

Too hard to work out what should be cached. Should BBC send the latest episode of Eastenders, Hustle, Tudors etc to every ISP before it's up for download? (Yes) Should Youtube try to guess which of its popular videos will be in demand next week? (No) Should Steam send out its new games? (Yes) You have to pick services where there aren't too many options, the iPlayer and Steam together have less than 2k items, and have a fairly predictable future demand.

<comment><AUTHOR> The point of what I'm trying to describe is an adaptive edge-caching service for the Internet. Support your ISP has cache a 100GB cache in your data center (probably RAM-based - think memcache). They could just leave in the cache those chunks that have the most demand from their customers. No one needs to decide if one "show" or another is most popular. Perhaps the cache would contain the first 15 minutes of Eastenders, and the last 30 minutes of the Oscars.

That's the beauty of a system like this is that is self-optimizes w/o a complex source-to-edge protocol.

</comment></comment><comment><AUTHOR> P.S. I also asked this on Quora - as an experiment to see what kind of answers I'll get there vs. here.

[http://www.quora.com/Why-isnt-a-content-addressable-cache- bu...](http://www.quora.com/Why-isnt-a-content-addressable-cache-built-into- the-Internet)

</comment><comment><USER9> It's called Bittorrent.

<comment><AUTHOR> Not really. Similar purpose, but it is not embedded in the network (every intermediate hop could support a layer of cache, from backbone providers down to consumer routers).

Note that Bittorrent is at least twice as inefficient as this scheme - <USER2> peer request requires the content go "up" and then "down" to the peer - through several intermediate hops.

This scheme, the data travels along the same path as the original content - <USER3> just doesn't ask for the same copy of the content over and over again from the source.</comment></comment>


IPhone hacked by Exploiting Safari in iOS 5, iOS 6 - <AUTHOR> http://thenextweb.com/apple/2012/09/19/dutch-security-researchers-hack-apple-iphone-4s-exploiting-safari/ <comment><USER2> Wonderful. So, now owners of the iPhone 4 and 4s will have two options:

1) Upgrade to a newer version of iOS to patch the exploit, and suffer a major functionality regression with regard to maps.

2) Not upgrade and risk having all the personal information on the phone stolen by a malicious website.

<comment><USER3> There's no middle ground? I assume that Opera wouldn't be vulnerable? What about the browsers that wrap UIWebView like Chrome?

<comment><USER2> Well... maybe I'm being too hyperbolic. But, I am under the impression that Safari is still the default handler for http things. So, links from the mail app or maps will open in Safari. I don't think it's _that_ outrageous to suggest that malicious links have ever been sent via email.

We can all sit here on HN and say that you shouldn't just go around clicking on everything that arrives in your inbox, but phishing is still something that banks deal with.

</comment></comment></comment><comment><USER4> "We really wanted to see how much time it would take a motivated attacker to do a clean attack against your iPhone. For me, that was the motivation. The easy part was finding the WebKit zero-day."

If finding the exploit was the easy part I'm curious what the hard part was.

Also, Apple should be incentivizing and supporting hackers more directly. It shouldn't have to take a (thankfully) white-hat hacker conference to get bugs like this fixed.

<comment><USER5> Probably defeating code signing and sandboxing

</comment></comment><comment><USER6> I wonder if this exploit can be used to jailbreak Iphone 5, untethered at least.. some previous, user-friendly online jailbreaks used .pdf vulnerabilities in Safari, but I am not sure if they used it with a combination of another privelege escalation exploit..

</comment><comment><USER7> It affects the iPhone 5, which is coming out tomorrow, not to mention all the other iDevices that can run iOS 6. I'm sure Apple will have it patched soon enough.

<comment><USER8> They'll patch it for iOS 6. Anyone else is on their own.

</comment></comment><comment><USER9> For a browser to be hacked days before it is even released on large scale speaks of Apple's security practices.

<comment> X-Istence the iOS 6 GM has been seeded for some time.

<comment><USER10> Not only that but we don't know how long the security hole has been there for. I've been running iOS 6 for months now, wouldn't be surprised if these guys did the same thing in preparation.</comment></comment></comment>