User talk:Erel Segal

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2021-09[edit]

@Erel Segal: In your edit of the page "Integer Programming" on 4th November, 2020 at 17:06 - you mention that "Lenstra's algorithm implies that ILP is polynomial-time solvable also in the dual case, in which n is varying but m (the number of constraints) is constant." Can you add citation to prove this claim? To the best of my knowledge, it is valid only if m+||A|| is constant (Theorem 2, Ganian et al. "Solving integer linear programs by exploiting variable-constraint interactions: A survey." Algorithms 12.12 (2019): 248). If your claim is indeed correct, could you please add the relevant citation or proof to support it?

I took it from the paper I cited, reference [12] in that page. But maybe I misunderstood. If you think it is incorrect, then you can fix it according to the survey paper you mentioned. --Erel Segal (talk) 22:15, 18 September 2021 (UTC)[reply]

Holes and topology[edit]

Hello, I redirected the page Hole (topology) that you created to homotopy group. The reason is that "hole" is not a standard notion in topology, and the content of the page was essentially duplicate with that of the page on homotopy groups. Best, jraimbau (talk) 12:05, 8 May 2022 (UTC)[reply]

@Jean Raimbault: The notion of a "hole", as it appears in Jiri Matousek's book (which was my source for the hole page), is much simpler than that of a homotopy group. It does not require any knowledge of group theory. For laypeople, that just want an intuitive understanding of the concept, it is much more useful to have a page on a "hole", than to bring them into a page that requires a deep understanding of group theory. In any case, if you still think a page on "hole" is not justified, then I think it should at least appear as a sub-page with title "hole". Maybe homotopical connectivity is a better place for it. --Erel Segal (talk) 14:00, 8 May 2022 (UTC)[reply]
Matoušek (and others) use the term "hole" loosely, and they do not give a formal definition for it. I don't think there ever has been a formal approach to the notion of hole that you propose that has been carried out independently of homotopy groups (and I personally feel that that the difficult part in the definition of those is the homotopy and not the group part). That's the main reason i don't think such an article is appropriate on wikipedia.
I'm not sure that redirecting as i did is the best solution though, you are welcome to discuss this on the main page of the wikiproject mathematics (i already launched a discussion a few days ago : https://en.wikipedia.org/wiki/Wikipedia_talk:WikiProject_Mathematics#Hole). Best, jraimbau (talk) 14:19, 8 May 2022 (UTC)[reply]

I have sent you a note about a page you started[edit]

Hello, Erel Segal Thank you for creating Homotopic connectivity.

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I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on Subdivision (simplicial complex). User:SunDawn, while examining this page as a part of our page curation process, had the following comments:

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I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on Optimal kidney exchange. User:SunDawn, while examining this page as a part of our page curation process, had the following comments:

Thank you for creating the article! Keep writing!

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Thanks for creating the fixed-point computation page[edit]

Dear Dr. Segal, thanks for creating this exceptional article. It was very interesting and enlightening to learn more about Brouwer-fixed point theorem from the computational perspective. Saung Tadashi (talk) 20:29, 17 April 2023 (UTC)[reply]

@Saung Tadashi: Thanks! --Erel Segal (talk) 10:09, 18 April 2023 (UTC)[reply]
Your recent article submission to Articles for Creation has been reviewed! Unfortunately, it has not been accepted at this time. The reason left by AngusWOOF was:  The comment the reviewer left was: Please check the submission for any additional comments left by the reviewer. You are encouraged to edit the submission to address the issues raised and resubmit after they have been resolved.
AngusW🐶🐶F (barksniff) 16:26, 18 April 2023 (UTC)[reply]
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Hello, Erel Segal! Having an article draft declined at Articles for Creation can be disappointing. If you are wondering why your article submission was declined, please post a question at the Articles for creation help desk. If you have any other questions about your editing experience, we'd love to help you at the Teahouse, a friendly space on Wikipedia where experienced editors lend a hand to help new editors like yourself! See you there! AngusW🐶🐶F (barksniff) 16:26, 18 April 2023 (UTC)[reply]

CS1 error on Multi-issue voting[edit]

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CS1 error on School choice[edit]

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Nomination for deletion of Template:Ordinal vs. cardinal utility[edit]

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Fixed. All the best: Rich Farmbrough 14:40, 31 January 2024 (UTC).[reply]

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Fixed. All the best: Rich Farmbrough 14:40, 31 January 2024 (UTC).[reply]

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Optimal design[edit]

I have posted a question regarding the name change at the talk page of the article. Will Orrick (talk) 11:11, 5 November 2023 (UTC)[reply]

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November 2023[edit]

Copyright problem icon Your edit to Draft:Random utility model has been removed in whole or in part, as it appears to have added copyrighted material to Wikipedia without evidence of permission from the copyright holder. If you are the copyright holder, please read Wikipedia:Donating copyrighted materials for more information on uploading your material to Wikipedia. For legal reasons, Wikipedia cannot accept copyrighted material, including text or images from print publications or from other websites, without an appropriate and verifiable license. All such contributions will be deleted. You may use external websites or publications as a source of information, but not as a source of content, such as sentences or images—you must write using your own words. Wikipedia takes copyright very seriously, and persistent violators of our copyright policy will be blocked from editing. See Wikipedia:Copying text from other sources for more information. — Diannaa (talk) 23:47, 7 November 2023 (UTC)[reply]

Ways to improve Median voting rule[edit]

Hello, Erel Segal,

Thank you for creating Median voting rule.

I have tagged the page as having some issues to fix, as a part of our page curation process and note that:

This is a very interesting subject and well-worthwhile for Wikipedia. However, there are entire sections that lack in-line citations. Consistent with Wikipedia's guidelines on citing sources, more in-line citations should be added.

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Nolabob (talk) 13:21, 14 November 2023 (UTC)[reply]

CS1 error on Median voting rule[edit]

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December 2023[edit]

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An article you recently created, Participatory budgeting experiments, is not suitable as written to remain published. It needs more citations from reliable, independent sources. (?) As written, the article contains too many statements and claims that are not supported by inline citations. Information that can't be referenced should be removed (verifiability is of central importance on Wikipedia). I've moved your draft to draftspace (with a prefix of "Draft:" before the article title) where you can incubate the article with minimal disruption. When you feel the article meets Wikipedia's general notability guideline and thus is ready for mainspace, please click on the "Submit your draft for review!" button at the top of the page. Mccapra (talk) 03:38, 30 January 2024 (UTC)[reply]

@Mccapra I do not understand your claim. There are 10 references, and every single paragraph in the writing is supported by an online citation. Can you please show me a single statement that is not supported by an online citation? --Erel Segal (talk) 06:41, 30 January 2024 (UTC)[reply]
” They had 180 subjects that are students from Zurich universities. Each subject had to evaluate projects in six input formats: unrestricted approval, 5-approval, 5-approval with ranking, cumulative with 5 points, cumulative with 10 points, cumulative with 10 points over 5 projects. The subjects were then asked which input format was most easy, most expressive, and most suitable. Unrestricted approval was conceived most easy, but least expressive and least suitable; in contrast, 5-approval with ranking, and cumulative with 10 points over 5 projects, were found significantly more expressive and more suitable. Suitability was affected mainly by expressiveness; the effect of easiness was negligible. They also found out that the project ranking in unrestricted approval was significantly different than in the other 5 input formats. Approval voting encouraged voters to disperse their votes beyond their immediate self-interest. This may be considered as altruism, but it may also mean that this format does not represent their preferences well enough.”
@Mccapra This is explaind in reference [6] which is cited at the beginning of the same paragraph, near the authors' names.
” They particularly compared the simple Greedy algorithm (which assumes cost-based satisfaction) with Equal Shares (assuming cardinality-based satisfaction). They found out that Greedy outcomes are highly sensitive to the input format used and the fraction of the population that participates. In contrast, MES outcomes are not sensitive to the type of voting format used. These outcomes are stable even when only 25–50% of the population participates in the election.”
@Mccapra Similarly, this is explaind in reference [4] which is cited at the beginning of the same paragraph, near the authors' names. Will it be better if I move these references to the end of the entire paragraph? --Erel Segal (talk) 10:02, 30 January 2024 (UTC)[reply]
yes that would be better. At the moment it looks like the bulk of the article us your original interpretation of the various studies, rather than a summary of the resesrchers’ own conclusions. Thanks Mccapra (talk) 13:54, 30 January 2024 (UTC)[reply]
@Mccapra done. Are there any other issues to fix? --Erel Segal (talk) 14:00, 30 January 2024 (UTC)[reply]

Moved back into mainspace and marked a# reviewed. Many thanks Mccapra (talk) 14:43, 30 January 2024 (UTC)[reply]


and so on. Mccapra (talk) 08:12, 30 January 2024 (UTC)[reply]

There are also several statements tagged as “clarification needed”. Mccapra (talk) 08:14, 30 January 2024 (UTC)[reply]
@Mccapra Fixed both clarification requests. Erel Segal (talk) 10:21, 30 January 2024 (UTC)[reply]

I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on N-dimensional polyhedron. SunDawn, while examining this page as a part of our page curation process, had the following comments:

Hello my friend! Good day to you. Thanks for creating the article, I have marked it as reviewed. Have a blessed day!

✠ SunDawn ✠ (contact) 15:10, 30 January 2024 (UTC)[reply]

@SunDawn: Thanks! --Erel Segal (talk) 15:13, 30 January 2024 (UTC)[reply]

I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on Power cone. SunDawn, while examining this page as a part of our page curation process, had the following comments:

Hello my friend! Good day to you. Thanks for creating the article, I have marked it as reviewed. Have a blessed day!

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✠ SunDawn ✠ (contact) 04:30, 31 January 2024 (UTC)[reply]

Unblock request[edit]

This user's unblock request has been reviewed by an administrator, who declined the request. Other administrators may also review this block, but should not override the decision without good reason (see the blocking policy).

Erel Segal (block logactive blocksglobal blockscontribsdeleted contribsfilter logcreation logchange block settingsunblockcheckuser (log))


Request reason:

Whenever I am connected to the Internet from my university's wifi network, I get a message that my IP range "212.179.0.0/16 " is blocked because it is a web-host provider, and so I cannot edit Wikipedia from within the university. Is it possible to make an exception for registered users for this IP?

Decline reason:

We can't do that, but you can go to WP:IPECPROXY and follow the instructions there to request IP block exemption by email, which would be the same thing. — Daniel Case (talk) 07:34, 1 February 2024 (UTC)[reply]


If you want to make any further unblock requests, please read the guide to appealing blocks first, then use the {{unblock}} template again. If you make too many unconvincing or disruptive unblock requests, you may be prevented from editing this page until your block has expired. Do not remove this unblock review while you are blocked.

--Erel Segal (talk) 13:04, 31 January 2024 (UTC)[reply]

@Daniel Case: I emailed them at `[email protected]` two weeks ago and got no reply. Is there any other option? --Erel Segal (talk) 08:47, 15 February 2024 (UTC)[reply]
I am increasingly warning people I tell this to that it is not going to come quickly ... the checkusers have a lot to do, and many of those things have higher priorities. We have been getting a lot of these requests lately because we've been more aggressive in blocking open proxies where we find them.
So ...
I have looked over your history, and
  • you have been editing (albeit not as heavily as some of us) for almost 16 years,
  • you have never been blocked during that time, and
  • you had IPBE for a year in the recent past without any issues.
I have thus decided to take it upon myself to grant you that right indefinitely (of course, any checkuser who eventually does review your request will have the right to revoke it if they feel there's a good reason, but from what I've seen of you I doubt there will be). I do not do this lightly ... admins used to be able to do it at their discretion, but then I gather someone was too free with those grants, and ... well, that's why we can't have nice things. Daniel Case (talk) 16:26, 15 February 2024 (UTC)[reply]

IP block exempt[edit]

I have granted your account an exemption from IP blocking. This will allow you to edit the English Wikipedia through full blocks affecting your IP address when you are logged in.

Please read the page Wikipedia:IP block exemption carefully, especially the section on IP block exemption conditions. Inappropriate usage of this user right may result in revocation. I hope this will enhance your editing, and allow you to edit successfully and without disruption. Daniel Case (talk) 16:28, 15 February 2024 (UTC) Daniel Case (talk) 16:28, 15 February 2024 (UTC)[reply]

@Daniel Case: Thanks a lot! --Erel Segal (talk) 11:55, 19 February 2024 (UTC)[reply]

I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on Median voting rule. North8000, while examining this page as a part of our page curation process, had the following comments:

Is this a duplication or overlap with Median voter theorem or Highest median voting rules?

North8000 (talk) 12:42, 8 February 2024 (UTC)[reply]

@North8000: No - this is why I put the "do not confuse" note at the top. I explain the differences between the terms in the "Related concepts" section at the bottom. --Erel Segal (talk) 18:46, 8 February 2024 (UTC)[reply]

Confusion about edit to NP-hardness[edit]

Hi, I was confused by your recent edit to the NP-hardness page. I agree with you (and was interested to learn!) that some undecidable problems are not NP-hard. But I don't see why this contradicts the informal statement "NP-hard problems are at least as hard as the hardest problems in NP". Indeed, the undecidable problems in question are not in NP.

Putting it otherwise, the informal statement says that "if Π is an NP-hard problem and Π' is a problem in NP, then Π is at least as hard as Π'". And indeed, then, Π' reduces to Π by definition. So I don't see why you find this informal statement to be inaccurate.

What do you think? Could you explain more (to me, and/or on NP-hardness) why you find the statement inaccurate? For now my opinion would be that we should mention the fact about non-NP-hard undecidable problems, but that we could keep the statement. Thanks! --a3nm (talk) 08:49, 10 February 2024 (UTC)[reply]

@A3nm: As the informal statement appeared at the top, I understood it as an alternative definition of NP-hardness, which is an "if and only if" statement. The "if" direction that you wrote is correct, but the other direction "if Π is at least as hard as all problems in NP then Π is NP-hard" is incorrect. I edited the paragraph to clarify. --Erel Segal (talk) 18:39, 10 February 2024 (UTC)[reply]
Thanks, that's clearer, but I'm still a bit confused. In the article you write "some problems are undecidable, and therefore even harder than all problems in NP". I'm not sure in which sense you mean this, formally: what does it mean that an undecidable problem is "harder" than a problem in NP, given that (as you point out) there is no reduction from one to the other?
I do see that you would informally expect an undecidable problem to be "harder" than an NP problem, but I don't see a way to state this as a formal claim, so I'm a bit uncomfortable with saying it explicitly.
How about rephrasing:
> Informally, if H is NP-hard, then it is "at least as hard as the hardest problems in NP". However, the opposite direction is not true: some problems are undecidable, and therefore even harder than all problems in NP, but they are provably not NP-hard (unless P=NP).
To something that avoids the issue:
> Informally, if H is NP-hard, then it is "at least as hard as the hardest problems in NP". However, there are some undecidable problems that are provably not NP-hard (unless P=NP).
What do you think? a3nm (talk) 12:16, 12 February 2024 (UTC)[reply]
Indeed, the word "hard" is overloaded. We should clarify the confusion between the daily use of "hard" (- difficult to solve), and the formal meaning of "hard" (- can be reduced from). I changed to "difficult to solve". Erel Segal (talk) 12:32, 12 February 2024 (UTC)[reply]

I have sent you a note about a page you started[edit]

Hello, Erel Segal. Thank you for your work on Fully proportional representation. North8000, while examining this page as a part of our page curation process, had the following comments:

Nice work

To reply, leave a comment here and begin it with {{Re|North8000}}. Please remember to sign your reply with ~~~~. (Message delivered via the Page Curation tool, on behalf of the reviewer.)

North8000 (talk) 22:19, 15 February 2024 (UTC)[reply]