Elliptic classes of Schubert varieties via Bott–Samelson resolution

Based on recent advances on the relation between geometry and representation theory, we propose a new approach to elliptic Schubert calculus. We study the equivariant elliptic characteristic classes of Schubert varieties of the generalized full flag variety G/B. For this first we need to twist the notion of elliptic characteristic class of Borisov–Libgober by a line bundle, and thus allow the elliptic classes to depend on extra variables. Using the Bott–Samelson resolution of Schubert varieties we prove a BGG‐type recursion for the elliptic classes, and study the Hecke algebra of our elliptic BGG operators. For G=GLn(C) we find representatives of the elliptic classes of Schubert varieties in natural presentations of the K theory ring of G/B, and identify them with the Tarasov–Varchenko weight function. As a byproduct we find another recursion, different from the known R‐matrix recursion for the fixed point restrictions of weight functions. On the other hand the R‐matrix recursion generalizes for arbitrary reductive group G.