tea.mathoverflow.net - Discussion Feed (Voted to delete)

Andreas Blass comments on "Voted to delete" (17950)

2011-12-28T15:35:56-08:00

I'd like to second Francois's request to refrain from deleting questions with potentially significant answers. Even though 10K users like me can vote to undelete, some (including me) and perhaps many don't have the time to go through all the recent deletions to see which ones we'd like to undo. It would be better if only the most obvious garbage were deleted.

Bill Johnson comments on "Voted to delete" (17946)

2011-12-28T14:10:30-08:00

> But there is a sarcastic answer which seems to be written specifically to embarrass the questioner. >

I assume you mean Mark Sapir's answer, which I did not find at all antagonistic to the OP but rather an attempt to show what is wrong with the question itself.

If you want to attribute bad motives to a user ("which seems to be written specifically to embarrass the questioner") you should have the courage to accuse under your real name.

Anonymous User comments on "Voted to delete" (17945)

2011-12-28T13:50:01-08:00

(Comment deleted by author; I think Bill Johnson's complaint is fair.)

François G. Dorais comments on "Voted to delete" (17940)

2011-12-28T11:28:30-08:00

Bill, these undeletions are the result of complaints from other community members. (Many of whom prefer not to participate on meta.) I appreciate the work of all community members. Unfortunately, it is also part of my role to mediate between community members with potentially conflicting interests, so I must sometimes make decisions that are not appreciated by everyone. I do my best to find a reasonable mediation point on a case-by-case basis.

I think my only guideline, which is not to delete questions with potentially significant answers without permission from the author, is reasonably clear and sound. Moderators do this when deleting stuff, and we also regularly undelete questions deleted by their owners for the same reason (see here).

Bill Johnson comments on "Voted to delete" (17939)

2011-12-28T10:48:36-08:00

Francois, on the one hand you want help from 10K users in cleaning up MO and on the other hand you complain about what they do. I suggest that you stick to your policy on locking and let the community work out what posts should remain. If three 10K users agree that a post should not remain deleted, your locking policy guarantees that it will not be deleted.

François G. Dorais comments on "Voted to delete" (17938)

2011-12-28T07:12:36-08:00

After more complaints, I again undeleted several questions with significant answers. One with 45 votes this time!

Please do not delete questions with potentially significant answers without first asking permission from the authors of these answers.

Tom Leinster comments on "Voted to delete" (17933)

2011-12-26T15:57:38-08:00

"Crackpottery" should clearly have two, so "crackpottish" wins my vote.

Andreas Blass comments on "Voted to delete" (17932)

2011-12-26T15:35:54-08:00

I agree with Kevin Walker (5 comments ago, at the moment) and with Joel Hamkins and Peter Krautzberger (much earlier in this thread) that questions should be deleted only if the question and all answers are clearly spammy/undergrad-homeworkish/crackpotish. I don't think prominent mathematicians should be scared away by some poor questions on the front page if those questions are marked as closed; that marking should suffice to indicate that such questions are unwanted and that community moderation is reasonably alert. (I accept Mark Sapir's assurance that some have been scared away; that's why my preceding sentence contains two occurrences of "should".) A couple of days ago, I started looking through the recent deletions, and I voted to undelete a few of them. For example, there was a question whose answer was well-known (at least to experts) and an answer consisting of just a link to a reference. I'd like that answer to be available if I ever need (or just want) related information. Also, someone who plans to ask a question and conscientiously checks whether it has already been asked might find it and thus refrain from re-asking if the earlier occurrence of the question was closed; if it was deleted, then it (presumably) can't be found and so would be re-asked.

(At the risk of setting off an even fiercer dispute: How many t's should there be in "crackpotish"? I just copied Kevin's spelling, because my dictionary, perhaps wisely, refuses to consider the matter.)

markvs comments on "Voted to delete" (17931)

2011-12-26T12:21:05-08:00

OK, at least I tried. Thanks to everybody who tried deleting this question.

Bill Johnson comments on "Voted to delete" (17930)

2011-12-26T11:25:55-08:00

Your policy on locking closed threads and deleted threads looks reasonable to me, Francois.

quid comments on "Voted to delete" (17929)

2011-12-26T10:40:55-08:00

Apparently votes to [un]delete can be repeated (unlike votes to close), so this oscillation between deleted and undeleted could go on indefinitely.

I was completely unaware of this; I thought this was like for open/close. If I had known this my opinion would have been clear from the start (as opposed to undecided). In my opinion this obvioulsy implies that deletion should only happen in very clear cases or after discussion that leads to this conclusion essentially without oposition. If not this ccould lead to complete chaos. [Added: or significant extra work for the moderators]

François G. Dorais comments on "Voted to delete" (17928)

2011-12-26T10:35:38-08:00

Since 43397 went back and forth a few times, it has been undeleted and locked. (The default for deletion wars is 'undelete' and the default for closing wars is 'close'.) The question is likely to stay locked indefinitely, but feel free to continue the discussion here.

Kevin Walker comments on "Voted to delete" (17926)

2011-12-26T09:58:57-08:00

The question has been deleted and undeleted several times in the last few days. (At the moment it's deleted, so I can't give exact numbers.) Apparently votes to [un]delete can be repeated (unlike votes to close), so this oscillation between deleted and undeleted could go on indefinitely. Perhaps the moderators should step in and propose/announce a policy for deleting non-spammy questions like this.

In answer to Andy Putman's question far above, I would propose limiting deletions to cases where the question, answers (if any) and comments (if any) are all clearly spammy/undergrad-homeworkish/crackpotish. If reasonable people might disagree on whether a question is in this class, then it shouldn't be deleted. I think the site would function just fine if there were no deletions at all.

Imagine a world in which the stackexchange software allowed only moderators to delete. Would MO be a disaster and unusable in this case? Of course not. I think that such a set up would be much preferable to the current situation, where any three easily irritated 10k users can delete a question.

markvs comments on "Voted to delete" (17925)

2011-12-26T06:19:24-08:00

From http://www.cicadamania.com/faq.html#a2: There is a cicada in India called Chremistica that emerges in synch with the World Cup (that is known as the World Cup cicada). Four is not a prime number. Can we finally delete this question? It is really a disgrace.

Mariano comments on "Voted to delete" (17924)

2011-12-24T12:49:49-08:00

(My favorite example of prime numbers in nature is the following: when I go to my gim, I have to give a card to a guy sitting at a desk near the front door; at any given time, he has quite a few of them, and as he gets bored he plays with the cards, sometimes arranging them in rectangular arrays and rearranging them, and so on---a kind of solitaire; I once heard him make the observation to another guy that someones he can't make a real rectangular array, only one which is 1 x something or something x 1 and that that is very annoying, so he waits for someone to come or leave. He is annoyed by prime numbers getting in the way!)

gilkalai comments on "Voted to delete" (17923)

2011-12-24T11:51:23-08:00

I agree with Mariano that we cannot give the fact that some mathematicians are turned off by such questions much weight. Personally I find it worse if after people make an effort to answer a question, or after people regard a certain question as a useful source then suddenly one day the question and all answers disappear without trace.

Regarding the question: It is an interesting question if prime number occurs in nature, and as the OP explained he didn't mean the occurrence of prime numbers just by coincidence - but because they are prime. The cicadas example seems like a serious one. As I understood there was no additional serious example in the answers. There was an answer elaborating on the cicadas example (which is welcome), and another answer criticizing this examle (which is also good if it was of good quality). There were also some answers joking about the question. And eventually the question was closed. For people who find it interesting this can be a useful source, for other people I dont see how this question can be of any harm. You can compare it to a question about practical applications (in real life) of prime numbers. Such a question do have mathematical content. I am aware of one answer (cryptography) but perhaps there are more. The 7-11 joke still applies.

Mariano comments on "Voted to delete" (17922)

2011-12-24T10:35:20-08:00

To be honest, the phenomenon described by Bill that

[certain] researchers who choose not to participate because of irrelevancies on the site

where irrelevancies means the occasional silly question, does not seem to me that important. I of course wish as many relevant people participate in the site, but I also expect people to be able to filter out a modicum of things they do not care for—even an Eminently Unimportant Mathematician like me manages to deal with it (I can't remember the last time one of my 'favorite tags' showed up in a question, although I know they do work because a semester ago a question by Kevin Lin appeared in yellow...)

I don't think the aspiration to have everyone on board is reasonable, and if some people are not willing to participate in the site, well, we will read their papers.

markvs comments on "Voted to delete" (17920)

2011-12-24T09:30:33-08:00

@Gil: Oh, I forgot, there was also an answer that we have 23 pairs of chromosomes and 23 is prime. I personally think that the number of chromosomes is more related to the dimension of the Leech lattice and the Monstrous Moonshine than to prime numbers in nature, but I would be virtually killed for such a comment.

markvs comments on "Voted to delete" (17919)

2011-12-24T09:22:34-08:00

@Michael: You do not need any prior knowledge above elementary school to understand the question. But, I believe, you do need certain "mathematical maturity" to appreciate it.

quid comments on "Voted to delete" (17918)

2011-12-24T09:19:02-08:00

I have still not completely made up my mind regarding the deletions, but in view of what Bill Johnson said, I have a question:

In what way will deletions of closed month-old questions or also if it happens more quickly affect whether, to give a current example, user Mike Massa asks questions and they are thus on the front page for a while?

Michael Greinecker comments on "Voted to delete" (17917)

2011-12-24T09:13:49-08:00

@Mark: I don't think that this is a sign of some bias. Even if MO would consists exclusively of Fields medalists, the highest voted questions would probably be of a (comparativey) lower level. The higher the level, the more specialized, and hence smaller, is the audience.

gilkalai comments on "Voted to delete" (17916)

2011-12-24T09:08:50-08:00

The question seems reasonable. I did not see the answers but, contrary to Bill, I think that the question itself - whether prime numbers occur in nature - does have interesting mathematical content.
(I did not know about the cicada example but I vaguely remember that around IAS there are some insects that are active once every 17 years.)

Bill Johnson comments on "Voted to delete" (17915)

2011-12-24T09:08:39-08:00

On the front page with the "newest" option there are 7 closed questions and at least two more that I guess will be closed soon. It is no wonder that many serious mathematicians take one look at MO and do not come back. Like Mark, I know researchers who choose not to participate because of irrelevancies on the site. Some lurk occasionally, but they no doubt miss threads that would be interesting due to the accumulation of irrelevant questions.

markvs comments on "Voted to delete" (17914)

2011-12-24T08:56:33-08:00

@Gil: To add to Bill's comment, there was also my "non-answer" where I tried to convince the OP that people are also part of nature and so convenience stores "7-11" and "101 dalmations" should be acceptable answers (my answer was highly downvoted) and there was another answer (also heavily downvoted) where somebody tried to argue that the cicadas example has no scientific base. Cicada people just could not tolerate an assault on their favorite insect. Now compare it with this very nice question http://mathoverflow.net/questions/84207/asymptotic-growth-of-antichains-in-divisibility-posets which has currently 3 up votes and no answers, and you will see which way MO is biased.

Angelo comments on "Voted to delete" (17913)

2011-12-24T08:55:14-08:00

I am posting the question below.

--

Finding primes in signals is seen as a sign of some kind of intelligence - see e.g. the role of primes in the search for extraterrestrial life (see e.g. here).
This is because there are relatively few examples of numbers that appear in nature because they are prime. One example of the use of prime numbers in nature is as an evolutionary strategy used by cicadas of the genus Magicicada (see e.g. here or here: [1])

My question:
Do you know of any other instances where prime numbers occur in nature? Could you please also give a source/link - and perhaps some background. Thank you.

[1] Goles, E., Schulz, O. and M. Markus (2001). "Prime number selection of cycles in a predator-prey model", Complexity 6(4): 33-38

Edit: Obviously many people misunderstood me. I didn't mean the occurrence of prime numbers just by coincidence - but because they are prime. The cicadas example - although being controversial - at least hints at some kind of evolutionary strategy.

Bill Johnson comments on "Voted to delete" (17912)

2011-12-24T08:44:01-08:00

Gil, the question was to give examples where prime numbers occur in nature. There were six answers, only one of which was substantive, and it simply and shortly described the cicada phenomenon, which had already been mention by the OP. This answer received 10 upvotes and the question itself 16 upvotes.

There is, IMO, zero mathematical content in the thread.

quid comments on "Voted to delete" (17911)

2011-12-24T08:41:21-08:00

@Gil Kalai: a rough answer from memeory, no guarantee for correctnes. Score question +16. Two answers with lower score (3 maybe) but on-topic. Roughly the question was whether there are/to collect examples of prime numbers in nature. Giving as initially starting point, or was this an asnwer, an example of the now much discussed cicadas, different types of which have developmental cycles the duration of which in years are different prime

[ADDED: Sorry regarding the answers I was apparently completely off.]

gilkalai comments on "Voted to delete" (17910)

2011-12-24T08:23:57-08:00

Regarding the question: "examples-of-prime-numbers-in-nature", what was the question? how many upvotes it had? how many answers?

Tom Leinster comments on "Voted to delete" (17905)

2011-12-24T07:30:43-08:00

Mark, I've moved our off-topic conversation to the n-Category Café, where it continues.

markvs comments on "Voted to delete" (17904)

2011-12-24T06:52:35-08:00

@Tom: The question you describe would be suitable for MO, in my opinion. Note the difference between "periods of dynamical systems" (a thing that can be defined) and "nature" (a thing that cannot be defined).

About our paper with Guba: look at the dunce hat example. It is exactly the definition of F that you give.

Tom Leinster comments on "Voted to delete" (17903)

2011-12-24T06:37:18-08:00

Mark, I still think that deleting is the wrong response. Closing already indicates that the question is not appropriate. Personally, I'm not even sure it should have been closed. I'd prefer it if it had been edited to make it better.

I'll say something about why I think this question is interesting (although not phrased particularly well). Mathematics has always been inspired by mathematical phenomena appearing in nature. By "nature" I mean everything in the physical world - physics, chemistry, biology etc., though for the purposes of this discussion I exclude human activity. There are examples of inverse square laws in nature, there are examples of exponential decay, and so on. Maybe there are directly observable examples of modified Bessel functions: who knows. Looking at how mathematics appears in nature often leads to new mathematics: take string theory, for instance, which may or may not be a good physical theory, but has certainly led to advances in mathematics.

So I think questions of the form "does such-and-such a piece of mathematics appear in nature?" are potentially interesting. Of course you could ask an unlimited number of such questions, but what makes this one stand out is that (i) there appears to be at least one example of prime numbers popping up non-coincidentally, and (ii) there don't appear to be so many examples that it's boring.

Out of interest, how would the pro-deletion people react to a question along the following lines? "I've been investigating such-and-such an abstract dynamical system, and when I ran some numerics on it, I discovered to my surprise that the period was always a prime number of units of time. Are there other examples of dynamical systems with unexpected prime number periodicity?" That's not phrased enormously well either, but would you consider a question of this type so beyond the pale that it deserved deletion?

Regarding the off-topic matter, if you have an easy deduction of the result described in that n-Category Café post from the result in your paper with Guba, I'd like to see it. I tried to find one years ago, when Fiore and I first did that work, but with no success: I couldn't see a direct way of deducing either characterization from the other. I also discussed this with Guba when he was visiting Glasgow in about 2005. But let's continue this discussion at the Café.

markvs comments on "Voted to delete" (17901)

2011-12-24T06:30:46-08:00

@Gil: I have sent you a message.

gilkalai comments on "Voted to delete" (17900)

2011-12-24T06:10:48-08:00

Mark: "I think MO has lost several extremely valuable contributors because of these questions"
" (I can give you concrete examples)"

Mark, I must admit that I find this hard to believe, but since I would like to keep my mind open about this possibility, please do give me concrete examples either here or privately to gil.kalai@gmail.com

markvs comments on "Voted to delete" (17899)

2011-12-24T06:02:44-08:00

@Tom: Although your idea makes sense, I do not agree with it. I think MO has lost several extremely valuable contributors because of these questions (I can give you concrete examples) and we need to deal with the problem somehow. Perhaps the moderators can make a special "retro.mathoverflow" site where they will keep the highly popular but unsuitable for a research oriented site questions. I think this idea has been discussed already.

On a completely different matter. I just looked at your Web site and found this note: http://golem.ph.utexas.edu/category/2010/01/f_and_the_shibboleth.html. Isn't this the same characterization of F as in http://front.math.ucdavis.edu/0301.5225 ? Sorry for the offtopic.

gilkalai comments on "Voted to delete" (17898)

2011-12-24T06:00:16-08:00

In my view, deletion of questions that gained some interest, (answers, upvotes, even remarks) is inappropriate. Closing questions is sufficient. (Now that many users have this power we realize this bad feature of MO software.)

Tom Leinster comments on "Voted to delete" (17897)

2011-12-24T05:26:34-08:00

I don't think questions should be deleted if multiple high-reputation users want to keep them. I'd go so far as to say that if even one high-reputation user (and you can't get any higher than JDH) has expressed an interest in keeping a question on the site, it should be kept. I wish the voting system implemented that rule.

Mark, Andy, Bill, and others who want to delete this, you may not be able to understand what value others see in this question, but you'll observed that others do see value in it. I think that under those circumstances, it would be respectful not to prevent everyone from reading it.

The fact that there were almost no interesting answers is interesting in itself. Maybe the famous cicadas really are the only known instance of this phenomenon. Judging this question to be a failure for that reason is like judging a scientific experiment to be a failure because it did not produce the result expected.

I wasn't very impressed, either, with the unconstructive tone of some of the answers. Yes, the OP could have been clearer about the term "nature" and the role of coincidence, but I thought it was pretty obvious what was meant. If the question is undeleted I might have a go at improving it.

I think deletion should be kept for obvious homework questions that receive no answer, spam, and the like.

Michael Greinecker comments on "Voted to delete" (17896)

2011-12-24T04:34:52-08:00

I fully agree with Peter Krautzberger. It should also be pointed out that it is usually very hard to explain to people that closing their question isn't exactly a criticism of their entire existence in this world. So I don' think anyone is encouraged to copy closed questions.

peter.krautzberger comments on "Voted to delete" (17895)

2011-12-24T01:27:38-08:00

+1 for JDH.

I think the "a real mathematician" argument flawed. In fact, a closed question reflects better on MO since it shows that the community is able to identify poor questions (it also shows how politely (or not) people react to poor questions). An aseptic community is not attractive and might be argued to discourage just as many people.

If at some point the software can be improved again, it might make sense to prevent such questions from appearing on positive lists (such as "most votes"). Although they might serve their purpose in searches since they discourage the repetition of poor questions.

Andy Putman comments on "Voted to delete" (17894)

2011-12-23T22:23:49-08:00

@Kevin : I think it is worthwhile to delete questions which reflect badly on MO (eg crackpottery, some of the nastier argumentative questions, absolute nonsense, etc). It'll keep them from popping up on searches, and this greatly improves the functionality of the site. What's the point of keeping that kind of stuff around?

Kevin Walker comments on "Voted to delete" (17893)

2011-12-23T21:56:51-08:00

+1 JDH. I think simply closing inappropriate questions is almost always sufficient, and I find the arguments in favor of being more aggressive with deletions to be very unconvincing. My impression is that this has not been much of an issue until very recently; in other words, MO got along just fine for two years using deletion only minimally. I see no compelling need to change course and start deleting any question which irritates three 10k users.

markvs comments on "Voted to delete" (17892)

2011-12-23T19:35:28-08:00

@Mariano: I did not give you all the reasons, and I do not want to open the discussion again. You are correct about page 25. A more relevant (for this question) reason: if you look at any question about primes on MO, there is a big chance that on the right of your page there is a link to the question about primes in nature. So it is not hidden at all. In fact that is how I rediscovered this question now.

François G. Dorais comments on "Voted to delete" (17891)

2011-12-23T19:35:14-08:00

After some complaints, I undeleted some questions that had answers with at least 5 votes, some with 10 or more votes. It would be preferable to ask permission from the authors before deleting their potentially significant answers.

quid comments on "Voted to delete" (17889)

2011-12-23T19:25:08-08:00

I do not have much against the deletions though I'd wish the process was a bit more transparent (this is actually a positive example, thank you Mark Sapir).

Yet, the gleefullnes and the feeling of superiority some display in doing so is a bit shocking.

Bill Johnson comments on "Voted to delete" (17888)

2011-12-23T19:01:37-08:00

I had the privilege of casting the final vote to delete. If that gets rid of the cicadas in my yard, that is a +++.

Andy Putman comments on "Voted to delete" (17887)

2011-12-23T18:55:43-08:00

I added a vote to delete the newly undeleted question, largely for the reasons Mark listed (though I would maybe put them a little more gently). I have to admit that I am baffled that anyone is defending it. I'm usually in favor of allowing a wide variety of question here, but this one is barely even mathematics.

Mariano comments on "Voted to delete" (17886)

2011-12-23T18:50:12-08:00

The question in question has 16 votes... The Real Mathematician would have to go to page 29 of the list of most upvoted questions to find it—I am sure a Real Mathematician has more Important Things to do than that!

markvs comments on "Voted to delete" (17885)

2011-12-23T18:42:49-08:00

@François G. Dorais: I do not know what you meant. Your post looks like a senseless personal insult. But unless you did not notice: the three people who voted to delete the cicadas question do not share a backyard.

markvs comments on "Voted to delete" (17884)

2011-12-23T18:35:11-08:00

@Tom: I think that closing is not enough. The argument for this was discussed on meta, I believe, several times. The shortest argument: if a real mathematician comes to MO first time and sees the list of most upvoted questions, he/she may never come again.

Tom Leinster comments on "Voted to delete" (17883)

2011-12-23T18:25:31-08:00

+1 JDH. Isn't closing enough?

François G. Dorais comments on "Voted to delete" (17882)

2011-12-23T18:24:43-08:00

Mark, if you can't distinguish between MO and your backyard...

markvs comments on "Voted to delete" (17881)

2011-12-23T18:22:31-08:00

@Andres: I did what I could about deleting and closing.

markvs comments on "Voted to delete" (17880)

2011-12-23T18:18:45-08:00

@JDH: I hate cicadas. They destroy trees in my backyard. Seriously, let's just say that I could use some very colorful language to describe this type of questions (and even more colorful if I were to use Russian). If you want to know why prime number $p$ appears in theory A, please ask this question yourself.

JDH comments on "Voted to delete" (17879)

2011-12-23T18:06:46-08:00

Please don't delete any more questions like this. It should be sufficient if the question is closed. I don't see any urgency for deletion.

I would have liked to see some mathematical physicists answer the current question by explaining the importance of primality in various fundamental theories. Surely it comes into string theory in various ways, and I would also have liked to learn of any other examples like the cicadas, if there were any.

Andres Caicedo comments on "Voted to delete" (17878)

2011-12-23T17:39:27-08:00

Clicking on the tools link on the MO page (on the bar next to your name) shows you a list of questions with votes to close/delete. All the delete ones listed "today" seem justified to me.

markvs comments on "Voted to delete" (17877)

2011-12-23T17:28:46-08:00

Thank you! I do have a couple of minutes. Could you post the links?

Andres Caicedo comments on "Voted to delete" (17876)

2011-12-23T17:25:05-08:00

It should be deleted now. (I was going to post a message letting you know.) There are a few other questions in need of attention as well (some closing, some deleting), if you have a couple of minutes.

markvs comments on "Voted to delete" (17875)

2011-12-23T17:07:21-08:00

I voted to delete this question: http://mathoverflow.net/questions/43397/examples-of-prime-numbers-in-nature-closed . Note that 2011 is prime so deleting this question before the end of the year makes a lot of sense.