English

On the (Local) Lifting Property

Operator Algebras 2026-05-22 v3 Functional Analysis

Abstract

The (Local) Lifting Property ((L)LP) is introduced by Kirchberg and deals with lifting completely positive maps. We give a characterization of the (L)LP in terms of lifting \ast-homomorphisms. We use it to prove that if AA and BB have the LP and FF is their finite-dimensional C*-subalgebra, then AFBA\ast_F B has the LP. This answers a question of Ozawa. We prove that Exel's soft tori have the LP. As a consequence we obtain that C(Fn×Fn)C^*(F_n\times F_n) is inductive limit of RFD C*-algebras with the LP. We prove that for a class of C*-algebras including C(Fn×Fn)C^*(F_n\times F_n), all contractible C*-algebras and all suspensions, the LLP is equivalent to Ext being a group. As byproduct of methods developed in the paper we generalize Kirchberg's theorem about extensions with the WEP, give short proofs of several, old and new, facts about soft tori, new unified proofs of Li and Shen's characterization of RFD property of free products amalgamated over a finite-dimensional subalgebra and Blackadar's characterization of semiprojectivity of them.

Keywords

Cite

@article{arxiv.2403.12224,
  title  = {On the (Local) Lifting Property},
  author = {Dominic Enders and Tatiana Shulman},
  journal= {arXiv preprint arXiv:2403.12224},
  year   = {2026}
}

Comments

It is 2nd version of the paper. A small correction in the characterization of the LLP is done. A result showing that each suspension is inductive limit of LP RFD C*-algebras is added

R2 v1 2026-06-28T15:24:56.232Z