English

Localizing invariants of constructible sheaves

K-Theory and Homology 2026-02-24 v2 Algebraic Topology Category Theory

Abstract

Given an open-closed decomposition of the stratifying poset, we construct a new semi-orthogonal decomposition of the \infty-category of constructible sheaves on a stratified space admitting an exit-path \infty-category. From this we obtain a direct sum decomposition of the localizing invariants of the \infty-category of constructible sheaves. Since the \ast-pullback to the open stratum in the usual (recollement) semi-orthogonal decomposition is not strongly left adjoint, this splitting does not follow from pure sheaf theory considerations. Instead, the splitting crucially relies on the exodromy equivalence: it implies that on the level of constructible sheaves, the \ast-pullback to a closed stratum and the !!-pushforward from an open stratum admit left adjoints. These new functors provide an additional semi-orthogonal decomposition (with the roles of open and closed reversed) in which the relevant functors are strongly left adjoint.

Keywords

Cite

@article{arxiv.2512.12810,
  title  = {Localizing invariants of constructible sheaves},
  author = {Qingyuan Bai and Peter J. Haine},
  journal= {arXiv preprint arXiv:2512.12810},
  year   = {2026}
}

Comments

Comments very welcome. v2. 20 pages. Corrected a typo in a formula in Proposition 2.6

R2 v1 2026-07-01T08:24:14.227Z