English

Cech cohomology over $\mathbb{F}_{1^2}$

Algebraic Geometry 2015-11-24 v1

Abstract

In this text, we generalize Cech cohomology to sheaves F\mathcal F with values in blue BB-modules where BB is a blueprint with 1-1. If XX is an object of the underlying site, then the cohomology sets Hl(X,F)H^l(X,\mathcal F) turn out to be blue BB-modules. For locally free OX\mathcal O_X-module F\mathcal F on a monoidal scheme XX, we prove that Hl(X,F)+=Hl(X+,F+)H^l(X,\mathcal F)^+=H^l(X^+,\mathcal F^+) where X+X^+ is the scheme associated with XX and F+\mathcal F^+ is the locally free OX+\mathcal O_{X^+}-module associated with F\mathcal F. In an appendix, we show that the naive generalization of cohomology as a right derived functor is infinite-dimensional for the projective line over F1\mathbb F_1.

Keywords

Cite

@article{arxiv.1511.06875,
  title  = {Cech cohomology over $\mathbb{F}_{1^2}$},
  author = {Jaret Flores and Matt Szczesny and Oliver Lorscheid},
  journal= {arXiv preprint arXiv:1511.06875},
  year   = {2015}
}

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14 pages