User talk:David Eppstein

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Speedy Keep

Your speedy keep here [1] claimed that the arguments were the same. The argument in the current AfD is that while the academic may be notable there is a complete lack of sources with which to create an article, from the responses in the AfD it can be seen that there is a complete lack of reliable independent sources to create an article with. This was not addressed in the first AfD. IRWolfie- (talk) 15:21, 4 April 2012 (UTC)

Are you going to address my concerns or do I need to take it to DRV? IRWolfie- (talk) 17:27, 4 April 2012 (UTC)

DRV seems appropriate if you are still not convinced by the two AfDs. —David Eppstein (talk) 18:47, 4 April 2012 (UTC)

The first AfD was closed properly, your close was inappropriate because the issues raised were different than the first AfD yet you closed it stating that the arguments were the same. Please point where the issue of the non-existence of sources to use in the article was raised in the first AfD. IRWolfie- (talk) 18:53, 4 April 2012 (UTC)

You reverted my revert of a bold addition on the article but you have not commented on the talk page, I suggest you do so per WP:BRD. IRWolfie- (talk) 17:17, 4 April 2012 (UTC)

I left an edit summary that says all I care to say about the matter. —David Eppstein (talk) 17:19, 4 April 2012 (UTC)

Dispute resolution survey

Dispute Resolution – Survey Invite Hello David Eppstein. I am currently conducting a study on the dispute resolution processes on the English Wikipedia, in the hope that the results will help improve these processes in the future. Whether you have used dispute resolution a little or a lot, now we need to know about your experience. The survey takes around five minutes, and the information you provide will not be shared with third parties other than to assist in analyzing the results of the survey. No personally identifiable information will be released. Please click HERE to participate. Many thanks in advance for your comments and thoughts. You are receiving this invitation because you have had some activity in dispute resolution over the past year. For more information, please see the associated research page. Steven Zhang DR goes to Wikimania! 02:23, 6 April 2012 (UTC)

Re 24968_Chernyakhovsky

Hi, please leave the article alone. There are literally hundreds of these added from the ISEF winnings, it is unfair to delete just this one. Thanks. 18.96.6.177 (talk) 04:31, 12 April 2012 (UTC)

Please see WP:WAX. —David Eppstein (talk) 04:33, 12 April 2012 (UTC)

Excuse me, but there are *hundreds* of these, and they weren't making anyone mad until Alexander Chernyakhovsky appeared. These are separate issues. Please do no pick on on article just because of your opinion on another. If you are going to do so, you have to delete 24977 Tongzhan and 24549 Jaredgoodman and all the rest like it.18.96.6.177 (talk) 04:38, 12 April 2012 (UTC)

It's true that I only do stuff to pages that I find out about — who can do otherwise? I'll be happy to prod those other two or as many others like them as you find but maybe at this point we should wait to see how the AfD goes. —David Eppstein (talk) 04:41, 12 April 2012 (UTC)

Then I am confused why you care about this one.18.96.6.177 (talk) 04:51, 12 April 2012 (UTC)

Because I found out about this one. —David Eppstein (talk) 04:52, 12 April 2012 (UTC)

Then why did you say something like "And delete his little dog", is that supposed to be funny?04:57, 12 April 2012 (UTC) — Preceding unsigned comment added by 18.96.6.177 (talk)

You never watched The Wizard of Oz? —David Eppstein (talk) 05:11, 12 April 2012 (UTC)

Apparently not.18.96.6.177 (talk) 05:23, 12 April 2012 (UTC)

R. W. H. T. Hudson

Prof. Eppstein, thank you for moving correctly Ronald Hudson's article. Giftlite (talk) 17:00, 12 April 2012 (UTC)

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DYK for Emanuels Grīnbergs

Casliber (talk · contribs) 00:04, 14 April 2012 (UTC)

WP:COPYVIO

In the AFD Wikipedia:Articles for deletion/Joachim Weickert you stated that you "didn't see much evidence of copyvio". Please cast your eye upon Talk:Joachim Weickert. If you don't see a problem, then please read Wikipedia:Copyright violations. You might also wish to read the information page Wikipedia:Copy-paste Much of the content of the article at the time of the AFD nomination was a violation of the Wikipedia terms of use. Thanks. Edison (talk) 05:12, 19 April 2012 (UTC)

Well, I agree that the comparison on the talk page looks too closely paraphrased for my taste, but there are only so many ways one can write "he got degrees X and Y and worked at universities Z and W." —David Eppstein (talk) 05:18, 19 April 2012 (UTC)

DYK for Mictyris guinotae

Materialscientist (talk) 16:10, 20 April 2012 (UTC)

DYK for Danièle Guinot

Materialscientist (talk) 16:10, 20 April 2012 (UTC)

º vs °

I considered users who type the degree sign as $\circ$ as lamers, but only before spotting your "180º rotation"[2]. Incnis Mrsi (talk) 09:47, 23 April 2012 (UTC)

Sorry, but ° and º look too similar to each other and are right next to each other on the keyboard (option-shift-8 vs option-0); it's hard to remember which is which. —David Eppstein (talk) 15:24, 23 April 2012 (UTC)

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Stupid bot, that one was deliberate, as indicated by the dab needed tag. —David Eppstein (talk) 15:22, 23 April 2012 (UTC)

DYK for Telephone number (mathematics)

Orlady (talk) 16:09, 26 April 2012 (UTC)

Maximum weighted average

Thought it might amuse you that after considerable discussion about a question on the Math Reference Desk today, User:Modocc found a 1995 paper of yours that answers it: Wikipedia:Reference desk/Mathematics#Calculating the 3 marks that drag a weighted average down the most. Regards, Qwfp (talk) 21:45, 30 April 2012 (UTC)

Thanks for letting me know. That's one of my more obscure ones... —David Eppstein (talk) 21:49, 30 April 2012 (UTC)

This is for you. Listen carefully.

http://www.youtube.com/watch?v=gfebdiErvDo — Preceding unsigned comment added by 86.24.46.135 (talk) 22:59, 2 May 2012 (UTC)

Dead link in article 'Rule 184'

Hi. The article 'Rule 184' has a dead link that could not be repaired automatically. Can you help fix it?

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This link is marked with {{Dead link}} in the article. Please take a look at that article and fix what you can. Thank you!

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 Done. Thanks for the heads-up. —David Eppstein (talk) 06:30, 6 May 2012 (UTC)

DYK for Tina Mion

Graeme Bartlett (talk) 00:04, 11 May 2012 (UTC)

Your continuing subversive anti-Western and anti-Ukrainian edits and reverts

David Eppstein, you serve your anti-Western and anti-Ukrainian Russian master, Vlad Putine, very well.

Your continuing anti-Ukrainian edits and reverts cannot be ignored.

Please familiarize yourself with Wikipedia policies before resorting again to your disruptive and subversive editing of Ukraine-related Wikipedia articles. Wikipedia policies may seem difficult for you to understand and to comply with, David Eppstein. However, believe me, this is just in the beginning. Please do not hesitate to ask other editors, including myself, if you need any explanations or clarifications. I would also recommend to you to use talk pages of pro-Western Ukrainian editors, asking questions and getting answers about Ukraine, BEFORE attempting to contribute the Ukraine-related Wikipedia articles.

Please do not resort again to your past habit of biased anti-Western edits about the Ukrainian matters.

. — Preceding unsigned comment added by 76.102.173.102 (talk) 06:12, 12 May 2012 (UTC)

Courcelle's

Thank you. The logical statement does, however, run over the edge on my browser. I think it needs to have line breaks between the conjuncts and disjuncts but not knowing the math syntax, I should leave that to you. History2007 (talk) 22:20, 13 May 2012 (UTC)

A barnstar for you!

	The Teamwork Barnstar
	Thank you for the re-write and reformatting of the article Albert Brahms which was formally proposed for deleltion. TeamWork is Wikipedian. Stephenwanjau (talk) 03:28, 14 May 2012 (UTC)

Thanks! Glad I could help. —David Eppstein (talk) 03:28, 14 May 2012 (UTC)

TB

Hello, David Eppstein. You have new messages at Talk:Lattice gas automaton.
Message added 20:38, 18 May 2012 (UTC). You can remove this notice at any time by removing the {{Talkback}} or {{Tb}} template.

benzband (talk) 20:38, 18 May 2012 (UTC)

Notability of Academics

I replied to your comments on the talk page of WP:PROF. NJ Wine (talk) 02:28, 23 May 2012 (UTC)

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DYK for Albert Brahms

Graeme Bartlett (talk) 08:04, 25 May 2012 (UTC)

proof outline

It is possible to write down this formula:

$\sum _{k=0}^{n}k^{2}=\sum _{k=0}^{n-1}\sum _{i=k+1}^{n}i$

This is an alternative way to group the sum of the squares: to quote an example, we assume n=5:

$0^{2}+1^{2}+2^{2}+3^{2}+4^{2}+5^{2}=$

$1+2+3+4+5+$

$2+3+4+5+$

$3+4+5+$

$4+5+$

$5$

In this representation the number five is summed 5 times, the number 4 is summed 4 times, and so on, until zero. After that, it is possible to use this result to solve the summation:

$\sum _{i=k}^{n}i={\frac {n(n+1)}{2}}-{\frac {k(k-1)}{2}}$

The main formula is equivalent to

$\sum _{k=0}^{n}k^{2}=\sum _{k=0}^{n-1}[{\frac {n(n+1)}{2}}-{\frac {k(k+1)}{2}}]$

After some agebraic manipulation it is possible to obtain:

${\frac {3}{2}}\sum _{k=0}^{n}k^{2}={\frac {n^{2}(n+1)}{2}}-{\frac {n(n-1)}{4}}+{\frac {n^{2}}{2}}$

This is equivalent to the desired formula.

86.24.46.135 (talk) 18:47, 29 May 2012 (UTC)

File:Steinhaus-Johnson-Trotter-Permutohedron.svg

With permutation labels from the permutohedron

Hi David. I don't really get your illustration of the Steinhaus–Johnson–Trotter algorithm. You have labelled your graph with the permutations from the Cayley graph and not with those from the permutohedron . Is this really what you have intended? I created the file on the right because that's how I understand "Hamiltonian path in the permutohedron". Lipedia (talk) 17:05, 30 May 2012 (UTC)

The algorithm works by swapping the values of elements in adjacent positions of the permutation, so we need the vertices of the graph to be labeled in such a way that this kind of swap corresponds to an edge. The Cayley graph has that property; the permutohedron doesn't. But the graphs are isomorphic (related to each other by inverting the labels) so the algorithm does indeed also find a Hamiltonian path in a graph isomorphic to the permutohedron. —David Eppstein (talk) 17:21, 30 May 2012 (UTC)

Indeed, your illustration is correct. To me the sentence

"Consecutive permutations in the sequence generated by the Steinhaus–Johnson–Trotter algorithm have numbers of inversions that differ by one, forming a Gray code for the factorial number system."

was misleading, because the path in the permutohedron is a textbook example of a "Gray code for the factorial number system" - but I wouln't say that about the path in the Cayley graph. There is e.g. a change from inversion vector (0,0,0,2) to (0,0,1,0). Is that a change in a Gray code?! See my change. Lipedia (talk) 12:36, 31 May 2012 (UTC)

proof outline

It is possible to write down this formula:

$\sum _{k=0}^{n}k^{2}=\sum _{k=0}^{n-1}\sum _{i=k+1}^{n}i$

This is an alternative way to group the sum of the squares: to quote an example, we assume n=5:

$0^{2}+1^{2}+2^{2}+3^{2}+4^{2}+5^{2}=$

$1+2+3+4+5+$

$2+3+4+5+$

$3+4+5+$

$4+5+$

$5$

In this representation the number five is summed 5 times, the number 4 is summed 4 times, and so on, until zero. After that, it is possible to use this result to solve the summation:

$\sum _{i=k}^{n}i={\frac {n(n+1)}{2}}-{\frac {k(k-1)}{2}}$

The main formula is equivalent to

$\sum _{k=0}^{n}k^{2}=\sum _{k=0}^{n-1}[{\frac {n(n+1)}{2}}-{\frac {k(k+1)}{2}}]$

After some agebraic manipulation it is possible to obtain:

${\frac {3}{2}}\sum _{k=0}^{n}k^{2}={\frac {n^{2}(n+1)}{2}}-{\frac {n(n-1)}{4}}+{\frac {n^{2}}{2}}$

This is equivalent to the desired formula.

86.24.46.135 (talk) 09:36, 1 June 2012 (UTC)