
In his lectures, Vanya explained how to construct a geometric Rmatrix using stable envelopes. I'll give another construction in the special case of instanton moduli space that uses the action of a certain Virasoro algebra on the cohomology of the Hilbert scheme of points on C^2 and explain why this construction coincides with the one we've already seen
Date  Speaker  Title 

September 13  Henry Liu  13/2 ways of counting curves. 
September 20  Dimitry Korb  DonaldsonThomas theory. 
September 27  Shuai Wang 
Curve counting via stable pairs in the derived category by R. Pandharipande, R. P. Thomas.
For a nonsingular projective 3fold $X$, we define integer invariants
virtually enumerating pairs $(C,D)$ where $C\subset X$ is an embedded curve and
$D\subset C$ is a divisor. A virtual class is constructed on the associated
moduli space by viewing a pair as an object in the derived category of $X$. The
resulting invariants are conjecturally equivalent, after universal
transformations, to both the GromovWitten and DT theories of $X$. For
CalabiYau 3folds, the latter equivalence should be viewed as a wallcrossing
formula in the derived category.
Several calculations of the new invariants are carried out. In the Fano case, the local contributions of nonsingular embedded curves are found. In the local toric CalabiYau case, a completely new form of the topological vertex is described. The virtual enumeration of pairs is closely related to the geometry underlying the BPS state counts of Gopakumar and Vafa. We prove that our integrality predictions for GromovWitten invariants agree with the BPS integrality. Conversely, the BPS geometry imposes strong conditions on the enumeration of pairs. 
October 4  Shuai Wang  Wall crossing, curve counting and Jacobi forms 
October 11 (Tuesday 7pm)  Iakov Kononov.  Equivariant vertex and topological strings 
October 18  Ivan Danilenko  Equivariant quantum cohomology of cotangent bundle of G/P I 
October 25  Ivan Danilenko  Equivariant quantum cohomology of cotangent bundle of G/P II 
November 1  Noah Arbesfeld 
In his lectures, Vanya explained how to construct a geometric Rmatrix using stable envelopes. I'll give another construction in the special case of instanton moduli space that uses the action of a certain Virasoro algebra on the cohomology of the Hilbert scheme of points on C^2 and explain why this construction coincides with the one we've already seen 
November 8  Noah Arbesfeld  The Rmatrix from the Virasoro algebras II 
November 14  Postponed (no talk)  Postponed (no talk) 
November 21  Thanksgiving (no talk)  Thanksgiving (no talk) 
November 29  Dimitry Korb  Quasimaps I 
December 6  Petr Pushkar  Quasimaps II 
December 13  Renata Picciotto  LandauGinzburg/CalabiYau correspondence for Fermat quintic 