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Math people:

I am trying to find a paper by Chapman referenced after Remark 2.3 in the paper "On the elementary symmetric functions of a sum of matrices" by R. S. Costas-Santos posted on the arXiv (arXiv:math/0612464v5 [math.AC] 17 Sep 2009). The only information in the references is "Amer. Math. Monthly 109 (7) (2002), 665–666". I looked up that issue of the Monthly and those pages are in the Problems Section. There is no paper by a Chapman in that issue. I do not know Chapman's first name. I have e-mailed R. S. Costas-Santos at the e-mail address given in his paper but I thought I might receive a response here as fast or faster.

The paper would have an identity involving the determinant of a sum of arbitrary matrices.

Stefan Smith
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  • Robin is one of the best problem-solvers in the world. If you look at the problem solutions given, credit is given to the person (or persons) whose answers are presented. Robin was the only person to get my last Problem correct. I'm not sure anyone else submitted any attempt at a solution. – Will Jagy Jul 30 '13 at 02:09
  • @WillJagy: I have seen Robin on other math sites in the past, and I agree with you. However, what problem are you referring to (did I miss the link)? – Amzoti Jul 30 '13 at 02:13
  • @Amzoti, I posted some comments after the fact at http://math.stackexchange.com/questions/255834/what-numbers-are-integrally-represented-by-4-x2-2-x-y-7-y2-z3 where I included the original question (Dec. 2010) and Robin's answer (Dec. 2012) including page numbers. I note that the only citation to Robin is "Solution by Robin Chapman, Exeter, UK." – Will Jagy Jul 30 '13 at 02:17

1 Answers1

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His name is Robin Chapman.

See: http://www.informatik.uni-trier.de/~ley/db/journals/tamm/tamm109.html

Alberto Facchini, Francesco Barioli, Robin Chapman, Ron Martin Carroll: Nonsingular Sums of Matrices: 10784. 665-666, 2002

Aside: Robin Chapman was actually a moderator on MSE (way before my time)!

Amzoti
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  • Wow, that was fast. The identity quoted in the paper I cited is surprising because it is difficult to say much about the determinant of the sum of matrices. I thought the special case proved by Chapman would require a longer proof. – Stefan Smith Jul 30 '13 at 02:32
  • Nice find! And looks as though it was a quick find for you! – amWhy Jul 31 '13 at 00:20