Talk:15 and 290 theorems

Dead link
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 * http://www.sciencenews.org/articles/20060311/bob9.asp
 * In 15 and 290 theorems on 2011-06-01 18:18:13, 404 Not Found
 * In 15 and 290 theorems on 2011-06-20 05:18:43, 404 Not Found

--JeffGBot (talk) 05:19, 20 June 2011 (UTC)

Dead link 2
During several automated bot runs the following external link was found to be unavailable. Please check if the link is in fact down and fix or remove it in that case!


 * http://www.math.duke.edu/~jonhanke/290/Universal-290.html
 * In 15 and 290 theorems on 2011-06-01 18:18:13, 404 Not Found
 * In 15 and 290 theorems on 2011-06-20 05:18:52, 404 Not Found

Expansion and rewrite
Since Manjul Bhargava won the Fields medal, and this is one of more easily understood results, I've rewritten this page to make it clearer to nonexperts, and added more references.

The page mentioned "integer valued integral quadratic forms". How are they different from integral quadratic forms? I think not at all... so I've changed this as part of my rewrite.

John Baez (talk) 02:10, 14 August 2014 (UTC)


 * The rewrite generally looks good to me. But the claim "For example, x2 + xy + y2 is integral but does not have integral matrix." is not true - it does have an integral matrix "(1 1 // 0 1)", since the article does not require the matrix to be symmetric. I suppose the "symmetric" condition should be added? --Roentgenium111 (talk) 10:31, 14 August 2014 (UTC)

--JeffGBot (talk) 05:19, 20 June 2011 (UTC)

Grammar in introduction
"... states that if a positive definite quadratic form with integer matrix represents all positive integers up to 15, then it represents all positive integers."

I'm not sure what a "positive definite quadratic form with integer matrix" is supposed to say. Perhaps a word is missing, as in "with integer matrix coefficients"? Or is the word "with" is not supposed to be there and this is supposed to be a matrix in a positive-definite quadratic integer form? — Preceding unsigned comment added by 73.71.83.221 (talk) 00:20, 12 April 2020 (UTC)