English

Equivariant semiprojectivity

Operator Algebras 2011-12-21 v1

Abstract

We define equivariant semiprojectivity for C*-algebras equipped with actions of compact groups. We prove that the following examples are equivariantly semiprojective: arbitrary finite dimensional C*-algebras with arbitrary actions of compact groups; the Cuntz algebras Od{\mathcal{O}}_d and extended Cuntz algebras Ed,E_d, for finite d,d, with quasifree actions of compact groups; the Cuntz algebra O{\mathcal{O}}_{\infty} with any quasifree action of a finite group. For actions of finite groups, we prove that equivariant semiprojectivity is equivalent to a form of equivariant stability of generators and relations. We also prove that if GG is finite, then C(G)C^* (G) is graded semiprojective.

Keywords

Cite

@article{arxiv.1112.4584,
  title  = {Equivariant semiprojectivity},
  author = {N. Christopher Phillips},
  journal= {arXiv preprint arXiv:1112.4584},
  year   = {2011}
}

Comments

44 pages; AMSLaTeX

R2 v1 2026-06-21T19:54:14.248Z