Algebraic and enumerative combinatorics seminar-Leigh Foster

Thursday, January 16, 2025 2:00 pm - 3:00 pm EST (GMT -05:00)

Title:The squish map and the SL_2 double dimer model

Speaker Leigh Foster
Affiliation University of Waterloo
Location MC 5479

 Abstract: A plane partition, whose 3D Young diagram is made of unit cubes, can be approximated by a "coarser” plane partition, made of cubes of side length 2. Two such approximations can be obtained by "rounding up” or "rounding down” to the nearest cube. We relate this coarsening (or downsampling) operation to Young's squish map, introduced in earlier work. We exhibit a related measure-preserving map between the 2-periodic single dimer model on the honeycomb graph, and a particular instance of Kenyon's SL_2 double dimer model on a coarser honeycomb graph. This allows us to apply existing computations from the 2-periodic single dimer partition function to a portion of the parameter space of the the harder double dimer model. We also specialize our map and exhibit new criterion for the signed-tilability of a closed region on the honeycomb graph.

There will be a pre-seminar presenting relevant background at the beginning graduate level starting at 1pm,