MathDB
No. ways of partitioning hexagon into rhombi is polynomial

Source: KoMaL A. 851

May 11, 2023
combinatoricscountingcombinatorial geometryalgebrapolynomial

Problem Statement

Let kk, \ell and mm be positive integers. Let ABCDEFABCDEF be a hexagon that has a center of symmetry whose angles are all 120120^\circ and let its sidelengths be AB=kAB=k, BC=BC=\ell and CD=mCD=m. Let f(k,,m)f(k,\ell,m) denote the number of ways we can partition hexagon ABCDEFABCDEF into rhombi with unit sides and an angle of 120120^\circ. Prove that by fixing \ell and mm, there exists polynomial g,mg_{\ell,m} such that f(k,,m)=g,m(k)f(k,\ell,m)=g_{\ell,m}(k) for every positive integer kk, and find the degree of g,mg_{\ell,m} in terms of \ell and mm. Submitted by Zoltán Gyenes, Budapest