Wed Oct 21 · 4:15pm
Richard P. Stanley Seminar in Combinatorics: Jonathan Boretsky (McGill)
Jonathan Boretsky of McGill University speaks on totally positive skew-symmetric matrices. Since such matrices always have nonpositive entries, they cannot be totally positive in the classical sense, so the talk calls one totally positive when it lies in the totally positive orthogonal Grassmannian. Boretsky gives a positivity criterion in terms of a fixed set of minors and describes the sign pattern of their Pfaffians.