The Horn problem and planar networks


Anton Alekseev

University of Geneva

Northeastern University

Thursday, November 29, 2012


Talk at 4:30 p.m. in 509 Lake Hall

Tea at 4:00 p.m. in 544 Nightingale Hall


Abstract:   The same set of inequalities comes up in two seemingly unrelated problems. The first one is the Horn problem on the specrtum of a sum of two Hermitian matrices with given eigenvalues (solved by Klyachko and Knutson-Tao). The second one is related to combinatorics of certain planar graphs (planar networks) with tropical Boltzmann weights assigned to the edges. The unexpected link between the two problems comes from the theory of Poisson-Lie groups.

The talk is based on joint work with M. Podkopaeva and A. Szenes.

Here are some directions to Northeastern University. Lake Hall and Nightingale Hall can be best accessed from the entrance on the corner of Greenleaf Street and Leon Street. The two halls are connected, with no well-defined boundary in between. In particular, 509 Lake Hall is on the same corridor as 544 Nightingale Hall.

There is free parking available for people coming to the Colloquium at Northeastern's visitor parking (Rennaisance Garage). The entrance is from Columbus Avenue. If coming by car, you should park there and take the parking talon. After the lecture, you may pick up the payment coupon from Andrei Zelevinsky.

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Posted:: November 18, 2012    URL: