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Apr 13, 2017 at 12:58 history edited CommunityBot
replaced http://mathoverflow.net/ with https://mathoverflow.net/
Feb 26, 2016 at 7:08 history edited j.c. CC BY-SA 3.0
fix sign error
Feb 23, 2016 at 23:48 comment added darij grinberg I'd say that the Proposition is a consequence of the Cauchy-Binet formula, the Laplace expansion along the first $n-k$ columns of $M$, and the result (classical?) that a minor of an invertible matrix equals the complementary minor of its inverse (here applied to the matrix with columns $a_1, \ldots, a_k, \widetilde{a}_{k+1}, \ldots, \widetilde{a}_n$, whose inverse is its own transpose). But your proof appears to be a lot simpler...
Feb 23, 2016 at 23:45 comment added darij grinberg Oh, I've just reread the proposition, and it does make sense now.
Feb 23, 2016 at 23:04 comment added j.c. @darijgrinberg I see that the $\tilde{a}$'s are not unique, but I think that it doesn't matter (though I should have written "positively oriented orthonormal basis" when introducing them). I am probably missing the thrust of your comment.
Feb 23, 2016 at 22:57 comment added darij grinberg Isn't your $M $ underdefined?
Feb 23, 2016 at 21:55 comment added Fan Zheng WLOG suppose $a_i$ are coordinate vectors. Then the result reduces to a trivial computation.
Feb 23, 2016 at 21:16 history asked j.c. CC BY-SA 3.0