English

Idempotents in triangulated monoidal categories

Category Theory 2017-03-06 v1

Abstract

In these notes we develop some basic theory of idempotents in monoidal categories. We introduce and study the notion of a pair of complementary idempotents in a triangulated monoidal category, as well as more general idempotent decompositions of identity. If E\mathbf{E} is a categorical idempotent then End(E)\operatorname{End}(\mathbf{E}) is a graded commutative algebra. The same is true of Hom(E,Ec[1])\operatorname{Hom}(\mathbf{E},\mathbf{E}^c[1]) under certain circumstances, where Ec\mathbf{E}^c is the complement. These generalize the notions of cohomology and Tate cohomology of a finite dimensional Hopf algebra, respectively.

Keywords

Cite

@article{arxiv.1703.01001,
  title  = {Idempotents in triangulated monoidal categories},
  author = {Matthew Hogancamp},
  journal= {arXiv preprint arXiv:1703.01001},
  year   = {2017}
}
R2 v1 2026-06-22T18:34:17.726Z