Dirk van Bree
The Virasoro constraints are a well-known conjecture in GW-theory. Recently, Moreira, Oblomkov, Okounkov and Pandharipande formulated versions for the PT-theory of a 3-fold and the Hilbert scheme of points on a surface. I will introduce a version of this conjecture for the moduli space of stable sheaves on a surface, generalising the Hilbert scheme case. Then I will explain how to verify this conjecture in a few explicit toric cases. This involves a combinatorial description of equivariant sheaves which is originally due to Klyachko.