Non-amenable simple C*-algebras with tracial approximation

TL;DR

This paper constructs two types of simple, separable C*-algebras with the same Elliott invariant as the Jiang-Su algebra, one exact and one non-exact, and analyzes their tracial approximation properties and classification.

Contribution

It introduces new examples of simple C*-algebras with prescribed invariants, including non-amenable and non-exact cases, expanding the understanding of tracial approximation and classification.

Findings

Constructed non-amenable simple C*-algebras with Jiang-Su invariant.

Demonstrated these algebras are essentially tracially in Z-stable class.

Provided models covering all weakly unperforated Elliott invariants.

Abstract

We construct two types of unital separable simple $C^*$-alebras $A_z^{C_1}$ and $A_z^{C_2},$ one is exact but not amenable, and the other is non-exact. Both have the same Elliott invariant as the Jiang-Su algebra, namely, $A_z^{C_i}$ has a unique tracial state, $$(K_0(A_z^{C_i}), K_0(A_z^{C_i})_+, [1_{A_z^{C_i}} ])=(\mathbb Z, \mathbb Z_+,1)$$ and $K_{1}(A_z^{C_i})=\{0\}$ ($i=1,2$). We show that $A_z^{C_i}$ ($i=1,2$) is essentially tracially in the class of separable ${\cal Z}$-stable $C^*$-alebras of nuclear dimension 1. $A_z^{C_i}$ has stable rank one, strict comparison for positive elements and no 2-quasitrace other than the unique tracial state. We also produce models of unital separable simple non-exact $C^*$-alebras which are essentially tracially in the class of simple separable nuclear ${\cal Z}$-stable $C^*$-alebras and the models exhaust all possible weakly unperforated Elliott invariants. We also discuss some basic properties of essential tracial approximation.