English

Equivariant bundles and absorption

Operator Algebras 2021-06-14 v2 Dynamical Systems

Abstract

For a locally compact group GG and a strongly self-absorbing GG-algebra (D,δ)(\mathcal{D},\delta), we obtain a new characterization of absorption of a strongly self-absorbing action using almost equivariant completely positive maps into the underlying algebra. The main technical tool to obtain this characterization is the existence of almost equivariant lifts for equivariant completely positive maps, proved in recent work of the authors. This characterization is then used to show that an equivariant C0(X)C_0(X)-algebra with dimcov(X)<\mathrm{dim}_{\mathrm{cov}}(X)<\infty is (D,δ)(\mathcal{D},\delta)-stable if and only if all of its fibers are, extending a result of Hirshberg, R{\o}rdam and Winter to the equivariant setting. The condition on the dimension of XX is known to be necessary, and we show that it can be removed if, for example, the bundle is locally trivial.

Keywords

Cite

@article{arxiv.2104.14927,
  title  = {Equivariant bundles and absorption},
  author = {Marzieh Forough and Eusebio Gardella},
  journal= {arXiv preprint arXiv:2104.14927},
  year   = {2021}
}

Comments

22 pages

R2 v1 2026-06-24T01:40:06.814Z