Homemath.CTarXiv:2605.30262

Semi-Bousfield classes and nonmonotone perversities

math.CTmath.ACmath.AG2026-05v1license

Abstract

In the generality of a rigidly-compactly generated tensor triangulated category, we introduce semi-Bousfield classes in terms of the vanishing of the tensor product in positive degrees with respect to a fixed reasonable tt-structure. We show that semi-Bousfield classes provide a common generalisation of Bousfield classes and compactly generated tensor-compatible tt-structures. Then we specialise to the setting of the unbounded derived category Dqc(X)\mathcal{D}_{\mathrm{qc}}(X) of a Noetherian scheme XX and show that the stratification bijection naturally extends to an assignment which takes a (not necessarily monotone) perversity on XX to a semi-Bousfield class in Dqc(X)\mathcal{D}_{\mathrm{qc}}(X). If XX is regular, this assignment constitutes a stratification of the whole semi-Bousfield lattice, while in the singular case, its image consists precisely of those semi-Bousfield classes arising from objects of finite Tor-dimension. Restricting this bijection to monotone perversities recovers the recent classification of compactly generated tensor-compatible tt-structures of Dubey and Sahoo, (arXiv:2204.05015).

Comments: 43 pages, comments are welcome

Cite

@article{arxiv.2605.30262,
  title  = {Semi-Bousfield classes and nonmonotone perversities},
  author = {Dolors Herbera and Michal Hrbek and Giovanna Le Gros},
  journal= {arXiv preprint arXiv:2605.30262},
  year   = {2026}
}