Talk:Roberts's triangle theorem

A fact from Roberts's triangle theorem appeared on Wikipedia's Main Page in the Did you know column on 6 November 2022 (check views). The text of the entry was as follows:

Did you know... that it took 90 years to replace the "unconvincing" original proof of Roberts's triangle theorem, on the number of triangles formed by systems of lines, with a correct proof?

A record of the entry may be seen at Wikipedia:Recent additions/2022/November. The nomination discussion and review may be seen at Template:Did you know nominations/Roberts's triangle theorem.

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Did you know nomination

The following is an archived discussion of the DYK nomination of the article below. Please do not modify this page. Subsequent comments should be made on the appropriate discussion page (such as this nomination's talk page, the article's talk page or Wikipedia talk:Did you know), unless there is consensus to re-open the discussion at this page. No further edits should be made to this page.

The result was: promoted by RoySmith (talk) 22:28, 2 November 2022 (UTC)[reply]

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... that it took 90 years to replace the "unconvincing" original proof of Roberts's triangle theorem, on the number of triangles formed by systems of lines, with a correct proof? Source: https://faculty.washington.edu/moishe/branko/BG223.How.many.triangles.pdf ("Unconvincing" is a quote from this source. the 90 years is a trivial calculation based on the 1889 date of the original proof and 1979 date of what Grünbaum calls the first correct proof).
- Reviewed: Template:Did you know nominations/Ira S. Allison

Created by David Eppstein (talk). Self-nominated at 00:47, 31 October 2022 (UTC).[reply]

General: Article is new enough and long enough
New enough: Long enough:

Policy: Article is sourced, neutral, and free of copyright problems
Adequate sourcing: Neutral: Free of copyright violations, plagiarism, and close paraphrasing:

Hook: Hook has been verified by provided inline citation
Cited: Interesting:

QPQ: Done.

Overall: @David Eppstein: good article. However, i'm not seeing where in the source has the word "unconvincing". Could you provide another source? Onegreatjoke (talk) 15:22, 1 November 2022 (UTC)[reply]

@Onegreatjoke: oops, sorry about that. The "unconvincing" quote is in the Fejes Toth source (doi:10.1080/00029890.1975.11993840, JSTOR 2318414, probably paywalled). Fejes Toth credits it to an earlier work of Grünbaum [1] which uses slightly different wording; the hook uses the wording from Fejes Toth. Additional footnotes added for proper credit for the quote. —David Eppstein (talk) 15:39, 1 November 2022 (UTC)[reply]

Alright, approving. Onegreatjoke (talk) 15:44, 1 November 2022 (UTC)[reply]