In this paper we survey geometric and arithmetic techniques to study the cohomology of semiprojective hyperkahler manifolds including toric hyperkahler varieties, Nakajima quiver varieties and moduli spaces of Higgs bundles on Riemann surfaces. The resulti ...
We study connections between the topology of generic character varieties of fundamental groups of punctured Riemann surfaces, Macdonald polynomials, quiver representations, Hilbert schemes on C-x x C-x, modular forms and multiplicities in tensor products o ...
Given a possibly reducible and non-reduced spectral cover pi: X -> C over a smooth projective complex curve C we determine the group of connected components of the Prym variety Prym(X/C). As an immediate application we show that the finite group of n-torsi ...
We give a cohomological interpretation of both the Kac polynomial and the refined Donaldson-Thomas-invariants of quivers. This interpretation yields a proof of a conjecture of Kac from 1982 and gives a new perspective on recent work of Kontsevich Soibelman ...