English

Microlocal homology

Algebraic Geometry 2025-09-23 v2 Representation Theory

Abstract

Let ZZ be an l.c.i. scheme over C\mathbb{C}. In this paper, we introduce a Kashiwara--Schapira-style functor of derived microlocalization, which we use to define a perverse sheaf μZ\mu_{Z} on the 1-1-shifted cotangent bundle, T[1]ZT^*[-1]Z. The sheaf μZ\mu_{Z} is designed to be a refinement of the microlocal homology of ZZ: a family of invariants introduced by Nadler that interpolates between the singular cohomology and Borel--Moore homology of ZZ. Our main result is an equivalence between μZ\mu_{Z} and the DT sheaf φT[1]Z\varphi_{T^*[-1]Z} on T[1]ZT^*[-1]Z. This provides an alternative construction for the DT sheaf in the case of a shifted cotangent bundle. The main step of our argument, which may be of independent interest, is a local computation -- closely related to one obtained recently by Kinjo using different methods -- providing a description of the classical microlocalization functor in terms of vanishing cycles.

Cite

@article{arxiv.2205.12436,
  title  = {Microlocal homology},
  author = {Kendric Schefers},
  journal= {arXiv preprint arXiv:2205.12436},
  year   = {2025}
}

Comments

Revised in response to referee feedback

R2 v1 2026-06-24T11:27:46.988Z