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Martin Sleziak
Martin Sleziak
12:38 PM
7
Q: von Neumann's characterization of orthogonally invariant matrix norms

Igor RivinVon Neumann has a result (rather well-known in convex analysis circles) which states that every orthogonally invariant matrix norm (meaning $\| P M Q\| = \| M \|,$ for any orthogonal $P, Q$)) is a symmetric gauge of the singular values. This is a very nice and very useful result, for which the bi...

fa.functional-analysis linear-algebra ho.history-overview
> The question is really one of history: how did von Neumann (who was already in Princeton at the time) decide to publish in a Tomsk University proceedings? Tomsk is very far from anywhere in Russia, and I am not aware of anything else that appeared there.
 
 
8 hours later…
Martin Sleziak
Martin Sleziak
8:49 PM
6
Q: Who first used the word "Simplex"?

Gérard LangWho first used the word "Simplex" to describe the considered geometric figure?

ho.history-overview convex-polytopes
 

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