Talk:Napkin folding problem

Intro

I've tried to improve the introduction, but I've been reverted. WP: lead says "As a general rule, the first (and only the first) appearance of the page title should be as early as possible in the first sentence and should be in boldface." No reason has been given for the way the opening sentence is written or for the redundancy of saying the Napkin folding problem is a problem. If this poor writing style exists in other math articles, it should be corrected there also. This isn't just Wikipedia policy it's standard to encyclopedias everywhere. ChildofMidnight (talk) 05:09, 15 December 2008 (UTC)[reply]

I don't care what wording we use, exactly, but can we avoid saying the "problem is a problem" in the first sentence? It reads like something from the Department of Redundancy Dept. Jonathunder (talk) 22:47, 15 December 2008 (UTC)[reply]

Comment - As there are no works regarding the Napkin folding problem and there are sources referencing as shown here [1] Margulis napkin problem, I would recommend changing the name of the piece. Redirect with Napkin folding problem to "Margulis napkin problem" should not be a problem at this point and the word problem should not be a problem (pun indeed). Thanks. ShoesssS ^Talk 00:59, 16 December 2008 (UTC)[reply]

I disagree. Both Arnold, Tarasov and Tabachnikov give credit to Arnold. The only source for "Margulis ..." is due to Lang, who credits the same newsgroup discussion originated by Propp you see on the bottom of the page. Scholar finds only sources which cite Lang as the origin of this citation. There are no credible references showing that Margulis had anything to do with this problem (I have done a careful study of the literature). Certainly, he did not publish anything. This is why I chose a neutral title (see also WP:BLP). Igorpak (talk) 01:53, 16 December 2008 (UTC)[reply]

Clarity

Could someone with more knowledge than myself clarify the section on formulations? No explanations and few links are given, making the different formulations somewhat impenetrable to those without sophisticated mathematical educations. Also, can it be clarified that for the formulation for which a positive solution has been found, the issue is not actually expanding the object's perimeter as stated in the introduction? —Preceding unsigned comment added by 74.79.251.248 (talk) 23:39, 31 December 2008 (UTC)[reply]

References

I've fixed up the references but I had trouble with a couple of them:

I could not find the "Yaschenko" article in the location described: those pages are occupied by "Mathematical entertainments—Geometry problems revisited" by Alexander Shen.
I have formatted the "Anton Petrunin" reference as best I could, not being able to read Russian.

If anybody can come up with something better, I'd be obliged. HTH HAND —Phil | Talk 14:12, 28 April 2010 (UTC)[reply]

edits of Mhym

1. The ref to the book of Pak wrong --- this book does not discuss similar problems at all.

2. If you do not know ref to Krat then it is not yet a reason to remove it. (BTW it is her thesis)

3. If I made English worse then correct it, but do not change to mathematically worse version.Tosha (talk) 03:59, 7 September 2010 (UTC)[reply]

I checked your claims. First, Pak's book does discuss in Section 40 the Napkin folding problem. You are factually wrong. On the other hand, I did not find any "unanswered problems there". I removed this ref, made the link to another ref which you claim does have these (my Russian is rusty, but I trust you on this). I kept Pak's book and added Demaine-O'Rourke's book, both useful references. Second, I searched for Krat's thesis without success. It seems it is not available anywhere and you don't seem to be able to provide the precise ref. I refer you to WP:RS (see also WP:LEDE and WP:POV) for discussions on these issues. Given the contentious matter I really do not see how we can justify inclusion of Krat's name in the lede. Third, I went through Tarasov's article and he does say what the article claims he does. That's all that is needed for WP, per WP:RS. We cal also include "According to Petrunin, Tarasov is incorrect..." or whatever, but I really don't see, given a controversy, how presenting a one-sided version can be claimed to be "mathematically better".

In summary, when you figure out how to make WP edits which might seem acceptable and in accordance with WP policies, I will work with you to get the article into a better shape, to improve English, etc. I suggest you start here, on the talk page, where we can discuss such edits and hopefully reach a consensus. Mhym (talk) 08:01, 7 September 2010 (UTC)[reply]

1. About "1" I was correct --- you simply do not read carefully.

2. About Krat --- if you need a ref: S. Krat, Approximation Problems in Length Geometry,Ph.D. thesis, Pennsylvania State University, 2005

3. About Tarasov --- the statement "both solutions were criticized by Tarasov" is incorrect --- he did it indepentently without knowing other solutions... Later he explain that his statement has more mathematical meaning, but you can not say that "solutions were criticized"...

4. Do not play with rules :) and do not assume that someone is bad --- it is bad for you. --Tosha (talk) 03:43, 8 September 2010 (UTC)[reply]

P.S. You also remove my note about Yaschenko which is VERY correct :)

Let's go over these again. 1. Apparently, either you are not reading the same version as I do or skipping the exercises. This is the most charitable way I can put it. But since you kept both book refs I added - I don't see what exactly is there to fight over. 2. This ref is pointless unless supplanted by reliable sources which claim to do what you purport. Again, please re-read WP:RS. I will stand firm on this and will bring other editors to argue this point if needed. WP is not a collection of rumors, and definitely not a place for WP:OR. 3. As I said, my Russian is rusty. Tarasov does say that, but I can agree with your neutral wording. That's fine. 4. I am not sure at all what you are referring to, but I think you are pushing to the edge of WP:PA, or at least "it is bad for you" can be interpreted that way. Given that you admit to be a non-native speaker, I will ignore this remark, but if another (direct or suspected) personal attack occurs, I will stop responding and take up the matter with appropriate WP admins. Finally, about P.S., you are probably right here - I rv your edits wholesale as much of it seemed inappropriate. In this instance this was a bad call. Mhym (talk) 09:09, 8 September 2010 (UTC)[reply]

I only mean that it is always better to think good about other people --- it is not an attack it is a suggestion. I do not want you to waive rules --- you can do such things in extreme cases, but we are not there (yet). It is true that getting somebodies thesis is not easy, but it is a solid reference (you can always get it in the library of the university).--Tosha (talk) 00:43, 9 September 2010 (UTC)[reply]

Misuse of notation

The O(n) notation in the main section is clearly misused (see Big O notation). These should all be $\theta (n)$ , I think. You see, even 2 is O(n). Please rework this. Mhym (talk) 09:31, 8 September 2010 (UTC)[reply]

People often use big O in the way I did, in fact I bet fewer people will recognize Theta. Anyway you could have edited it yourself. I'll go and stick it in since you seem to thing that whole edits need to be reverted on account of things like that. Dmcq (talk) 09:44, 8 September 2010 (UTC)[reply]

I actually agree. Theta notation is a bit too advanced for the loose discussion on that page, and Big O is quite a bit misleading (at the end you want a lower bound but write the upper bound). So please figure out how to phrase it carefully and clearly, or I intend to remove this rather technical discussion. Mhym (talk) 09:52, 8 September 2010 (UTC)[reply]

I've seen it phrased the way I put it somewhere else but Lang's book divides the napkin into (N-1)^2 squares to give N^2 spikes each of length 1/(2(N-1)) and in the limit with thinning the perimeter is 2.N^2/(2(N-1)). I'm not sure that would really help but if you like I could stick that in instead. He and others had made sea urchins which when flattened would have solved the problem a number of years before if they'd known about it, his sea urchin thinned and flattened would have given a perimeter of 6.25 instead of 4. Dmcq (talk) 10:07, 8 September 2010 (UTC)[reply]

I have no problem with this argument. I am just unhappy with the way it was presented in the article. In fact, given that the rest of the article is rather sketchy, this quantitative outburst seems out of place. If the whole point is to say that the perimeter can be made as large as desired, let's just say so and move on to other issues. Mhym (talk) 10:29, 8 September 2010 (UTC)[reply]

The description gives enough for someone to make their own version of the problem by crumpling so the non rigid origami version is solved easily once one knows the trick. Otherwise the article gives no idea of how to do it. Dmcq (talk) 11:23, 8 September 2010 (UTC)[reply]

You made the math even more complicated to a lay reader, and non-origami expert still has no clue what do these terms mean (I checked - there are no WP pages on these origami constructions). I decided to do a compromise and summarized your edits. Hopefully, this is still factually correct what I wrote. Please check. Thank you. Mhym (talk) 11:32, 8 September 2010 (UTC)[reply]

I'd have though more should be put in about Alexey Tarasov's solution instead of chopping down on other things. That was extremely elementary mathematics and I can't see many people coming to this article that couldn't understand that. I think you have made the article considerably less good by stopping people understanding the gist of a solution. Also I don't know what origami terms you're talking about, the only special one was bird base which is actually included in wikipedia and there are pictures of it in wikimedia commons. Is it rigid origami you don't like? that is a far bettwer description than piecewise linear which was a quite incomplete description. Dmcq (talk) 12:43, 8 September 2010 (UTC)[reply]

I am not an edit warrior, just trying to improve the article and to conform it with WP policies. Too many WP math articles (like this one) are too incomprehensible for an average reader, which makes both mathematicians and readers unhappy. If you could phrase what you want to say in a plain language, go ahead. If not - I say the links to research works are enough. The reader cal follow them. Remember WP:Not a storage. Mhym (talk) 12:33, 9 September 2010 (UTC)[reply]

Most people would have no access to many of the references and wouldn't know russian. And they'd be interested in having a solution. And the maths I put in would be accessible to a child starting algebra. Often the plainest language is maths, just one needs to try and get the simplest one can without going too far. I am not currently concerned with the coupon collectors problem so that is irrelevant. Basically what you have now is an article that lists people the reader may not be particularly interested in, doesn't show them even a glimmer of a solution and directs them to russian articles or expensive books that won't be in their library and need a far higher level of maths than most of them have. How is the average reader supposed to get hold of Tarasov's solution and read it for instance? Dmcq (talk) 15:23, 9 September 2010 (UTC)[reply]

I am not sure what you are trying to achieve with your complaints. Please propose your corrections. We can then discuss them. Mhym (talk) 18:53, 9 September 2010 (UTC)[reply]

Your actions so far do not seem to be helpful for the article. You removed a short description of a solution saying it was excessive and object to some very elementary maths saying it was excessive and you seem to think the readers should go away somewhere else for anything they might be interested in and look up hard to obtain journals and read russian. I will put in a description of a solution again and I do see you as an edit warrior here acting against the best interests of Wikipedia. Dmcq (talk) 23:25, 9 September 2010 (UTC)[reply]

You are no longer discussing the article. You are discussing me as an editor. I do not and will not take part in such discussions. Happy editing! Mhym (talk) 08:25, 11 September 2010 (UTC)[reply]

Fine by me as there seemed to be a zero meeting of minds about what a good article is or what Wikipedia is about. Dmcq (talk) 13:57, 11 September 2010 (UTC)[reply]

Sinking flaps

"sinking flaps" is not defined at it's linked location 86.129.129.50 (talk) 14:00, 11 August 2011 (UTC)[reply]

Yes you're right. It mentions sink but doesn't illustrate it and it really should. It is an important operation in more complicated models. Sinking is pushing in a tip like pushing in the top of a cone rather than folding it over. The easiest way sometimes is to partially unfold the model, and there's techniques for making it easier but it definitely isn't a straightforward fold. I'll note it in the other article's talk page. Dmcq (talk) 16:29, 11 August 2011 (UTC)[reply]

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