A complete classification of negative stringy Hodge numbers

Abstract

The stringy $E$-function is a fundamental invariant of varieties with log-terminal singularities, which was introduced by Batyrev as a singular analogue of the Hodge--Deligne polynomial. Its coefficients (up to an appropriate sign) are the stringy Hodge numbers $h_{\mathrm{str}}^{p,q}(Y)$. We completely determine when these coefficients are universally non-negative:~for each triple $(n,p,q)$, we classify when $h_{\mathrm{str}}^{p,q}(Y)\ge 0$ for every projective Gorenstein canonical $n$-fold $Y$; we answer this question both when we assume $E_{\mathrm{str}}(Y;u,v)$ is a polynomial and when we drop this condition. As a consequence, we settle Batyrev's non-negativity conjecture in all dimensions:~it holds in dimensions at most $4$ and fails in every dimension at least $5$.