Welcome to the homepage of the Online Representation Theory Seminar. The Seminar is an initiative to bring together faculty working in Algebra and Geometry, and mostly based in Italian Universities, with interests in Representation Theory. The talks cover a wide range of topics, including Lie Theory, Combinatorics, and Geometric Representation Theory.

The activity is currently being coordinated by Andrea Appel (Parma), Fabio Gavarini (Roma – Tor Vergata), Martina Lanini (Roma – Tor Vergata), and Francesco Sala (Pisa).

We usually meet on Fridays from 3:00pm to 4:00pm (Central European Time) on a Microsoft Teams Channel. If you want to stay informed about the seminars and receive the link to attend the seminar, please subscribe to the following mailing list: 

Speaker: Olivier Schiffmann (CNRS and Université de Paris-Saclay, France)

March 5, 2021 – 3 pm

Title: Cohomological Hall algebras associated to ADE surface singularities

Abstract: To a (reasonable) CY category C of global dimension two one can attach an associative algebra — its cohomological Hall algebra (COHA) — which is an algebra structure on the Borel-Moore homology of the stack of objects in C. In examples related to quivers (i.e. when C is the category of representations of the preprojective algebra of a quiver Q) this yields (positive halves) of Kac-Moody Yangians. In ongoing joint work with Diaconescu, Sala and Vasserot, we consider the case of the category of coherent sheaves supported on the exceptional locus of a Kleinian surface singularity. This is related to the above quiver case by a ‘2d-COHA’ version of Cramer’s theorem relating the (usual) Hall algebras of two hereditary categories which are derived equivalent.

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Stephen Griffeth (Universidad de Talca, Chile)

March 12, 2021 – 3 pm

Title: Ideals of subspace arrangements and representation theory

Abstract: I’ll discuss results linking the study of certain highly symmetric arrangements of linear subspaces in affine space to representation theory, describing how to obtain qualitative information (e.g., is the arrangement Cohen-Macaulay?) and quantitative information (e.g., what is the Hilbert series of the ideal of the arrangement?) using techniques from the representation theory of Cherednik algebras.

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Daniele Valeri (University of Glasgow, UK)

March 19, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Valerio Toledano Laredo (Northeastern University, USA)

March 26, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Giovanna Carnovale (Università di Padova, Italy)

April 9, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Kenji Iohara (CNRS and Université de Lyon, France)

April 23, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Anton Mellit (University of Vienna, Austria)

May 7, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Sachin Gautam (Ohio State University, USA)

May 21, 2021 – 3 pm

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. The access link will be sent to the mailing list a day in advance.

Speaker: Oleksandr Tsymbaliuk (Purdue University, USA)

June 25, 2021 – TBA

Title: TBA

Abstract: TBA

The seminar will be broadcasted online. More information will be posted before the date of the seminar.