Presheaf structures governed by oriented matroids and pseudohyperplane arrangements

@misc{coron2026presheaf,
  title = {{Presheaf structures governed by oriented matroids and pseudohyperplane arrangements}},
  author = {Basile Coron and Denis Lyskov},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.31837},
  eprint = {2610.31837},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.31837},
}

TY  - UNPB
TI  - Presheaf structures governed by oriented matroids and pseudohyperplane arrangements
AU  - Basile Coron
AU  - Denis Lyskov
PY  - 2026
DA  - 2026/10/22
PB  - arXiv
DO  - 10.48550/arxiv.2610.31837
UR  - https://arxiv.org/abs/2610.31837
AB  - We study higher complements of pseudohyperplane arrangements and the specialization maps between them, induced by degenerations. We develop a presheaf formalism on oriented matroids and weak maps, which model degenerations. Our main constructions are the posets of weighted and weightwise topes, which provide functorial combinatorial models for higher complements and their specialization morphisms. Their presheaf structure yields a deletion-contraction homotopy pushout, from which we derive a uniform combinatorial proof of the integral cohomology presentation for all n ≥ 2. This presentation is natural with respect to weak maps and identifies cohomology rings with higher Orlik-Solomon algebras extending the known formulas for linear arrangements to non-realizable oriented matroids. Finally, we equip Deligne groupoids with a presheaf structure and identify them functorially with the fundamental groupoids of the complexified complements.
ER  -