Generalized Hilbert-Kunz Multiplicity for Families of Ideals
Stephen Landsittel, Sudipta Das
TL;DR
This work develops a comprehensive framework for generalized Hilbert-Kunz multiplicities of $p$-families of ideals in Noetherian local rings of positive characteristic. It introduces the Amao-type multiplicity $a_F(I,J)$ and proves that, under linear growth (and LC) conditions, the generalized HK multiplicity $e_{gHK}(I_{\bullet})$ equals the asymptotic limit of Amao-type values, $e_{gHK}(I_{\bullet}) = \lim_{q'\to\infty} a_F(I_{q'}, (I_{q'})^{sat})/(q')^d$. The core technical advance is a general volume formula linking limits of lengths to volumes of truncated $p$-bodies derived from OK-domain valuations and cone geometry; this yields a volume-equals-multiplicity correspondence and enables applications to BBL weakly $p$-families. The results unify and extend classical HK theory, provide existence criteria, and connect asymptotic invariants to geometric data via a robust valuation-driven framework.
Abstract
In this paper, we initiate a systematic study of the generalized Hilbert-Kunz multiplicity for families of ideals in a Noetherian local ring (R,m) of positive characteristic, and introduce a new asymptotic invariant called the Amao-type multiplicity. We establish that, for a p-family of ideals, the generalized Hilbert-Kunz multiplicity arises as the limit of Amao-type multiplicities.
