# On a categorical framework for classifying C*-dynamics up to cocycle conjugacy

## TL;DR

This paper develops a categorical framework for classifying C*-dynamics up to cocycle conjugacy, extending known functors and establishing intertwining results to facilitate classification efforts.

## Contribution

It introduces a new categorical approach to C*-dynamics classification, generalizing intertwining techniques and allowing for inductive limits and extended functors.

## Key findings

- Categorical framework for G-C*-algebras with cocycle morphisms
- Extension of functors to the new categorical setting
- Generalization of intertwining results for classification

## Abstract

We provide the rigorous foundations for a categorical approach to the classification of C*-dynamics up to cocycle conjugacy. Given a locally compact group $G$, we consider a category of (twisted) $G$-C*-algebras, where morphisms between two objects are allowed to be equivariant maps or exterior equivalences, which leads to the concept of so-called cocycle morphisms. An isomorphism in this category is precisely a cocycle conjugacy in the known sense. We show that this category allows sequential inductive limits, and that some known functors on the usual category of $G$-C*-algebras extend. After observing that this setup allows a natural notion of (approximate) unitary equivalence, the main aim of the paper is to generalize the fundamental intertwining results commonly employed in the Elliott program for classifying C*-algebras. This reduces a given classification problem for C*-dynamics to the prevalence of certain uniqueness and existence theorems, and may provide a useful alternative to the Evans--Kishimoto intertwining argument in future research.