Center Seminar on Mondays / Fall2021

Center for Advanced Studies
Seminar on Mondays at 17.00 via Zoom

September 20, 2021 / Dmitry Belyaev (Mathematical Inst., Univ. of Oxford)
= = Smooth Gaussian fields
September 27, 2021 / Roman Gonin (Skoltech, HSE Univ.)
= = Semi-infinite construction of twisted Fock module for quantum toroidal gl_1
October 4, 2021 / Leonid Rybnikov (HSE Univ., Kharkevich Inst.)
= = Bethe subalgebras in Yangians and Kirillov-Reshetikhin crystals
October 11, 2021 / Serguei Barannikov (Skoltech & CNRS, IMJ, Paris Univ.)
= = Persistence bar-codes and topological obstructions in deep neural networks’ learning
[ link to access the Seminar zoom 94069697919 ]

October 18, 2021

Philippe Di Francesco
(Univ. of Illinois & IPhT Saclay)
Triangular ice: combinatorics and limit shapes

We consider the triangular lattice version of the two-dimensional ice model with suitable boundary conditions, leading to an integrable 20 Vertex model. Configurations give rise to generalizations of Alternating Sign Matrices, which we call Alternating Phase Matrices (APM). After reviewing a few facts on the square lattice version and the role of integrability, we compute the number of APM of any given size in the form of a determinant, which turns out to match the number of quarter-turn symmetric domino tilings of a quasi-Aztec square with a central cross-shaped hole. We also present results/conjectures for triangular Ice with other types of boundary conditions, and results on the limit shape of large typical configurations, obtained by applying the so-called “Tangent Method” of Colomo and Sportiello.
(based on work with E. Guitter and B. Debin)