Cohomological $\chi$-dependence of ring structure for the moduli of one-dimensional sheaves on ${\mathbb{P}}^2$

Abstract

We prove that the cohomology rings of the moduli space $M_{d,\chi }$ of one-dimensional sheaves on the projective plane are not isomorphic for general different choices of the Euler characteristics. This stands in contrast to the $\chi$-independence of the Betti numbers of these moduli spaces. As a corollary, we deduce that $M_{d,\chi }$ are topologically different unless they are related by obvious symmetries, strengthening a previous result of Woolf distinguishing them as algebraic varieties.

Added Section 1.3 on the structure of the proof; final version to appear in Forum Math. Sigma