Семинар М.Э.Казаряна и С.К.Ландо "Характеристические классы и теория пересечений" возобновляет свою работу в четверг 4 сентября в 19.00 (обратите внимание на смену дня недели! аудитория уточняется).
11 сентября, четверг
I am going to discuss the blow-down procedure for differential forms on the Kimura-Stasheff-Voronov space satisfying the gluing axiom. As a result, we obtain a CohFT on the usual moduli space of curves whose correlators related to the original correlators of TCFT via Givental
4 сентября, четверг
M.Kazarian and S.Lando found a 1-parametric interpolation between Kontsevich and Hurwitz partition functions, which entirely lies within the space of KP tau-functions. V.Bouchard and M.Marino suggested that this interpolation satisfies some deformed Virasoro constraints. However, they described the constraints in a somewhat sophisticated form of AMM-Eynard equations for the rather involved Lambert spectral curve. Instead, one can present the relevant family of Virasoro constraints explicitly. They differ from the conventional continuous Virasoro constraints in the simplest possible way: by a constant shift u^2/24 of the L_{-1} operator, where u is an interpolation parameter between Kontsevich and Hurwitz models. This trivial modification of the string equation gives rise to the entire deformation which is a conjugation of the Virasoro constraints L_m -> U L_m U^{-1} and "twists" the partition function, Z_{KH}= U Z_K. The conjugation U is expressed through the previously unnoticed operator N_1 which annihilates the quasiclassical (planar) free energy of the Kontsevich model, but does not belong to the symmetry group GL(\infty) of the universal Grassmannian.
