$C^*$-diagonal of inductive limit of $1$-dimensional NCCW complexes
Dolapo Oyetunbi
TL;DR
This work proves the existence of a $C^*$-diagonal for unital inductive limits of $1$-dimensional NCCW complexes with trivial $K_1$-groups and injective connecting maps. It develops $n$-standard maps to approximate arbitrary unital $^*$-homomorphisms between such complexes, and introduces a $ ext{D}$-pair structure to realize these maps via piecewise unitary conjugations, extending ideas from $1$-dimensional CW complexes to NCCW settings. By constructing diagonals on the building blocks and ensuring their compatibility through the inductive system, the paper shows that the limit carries a Cartan subalgebra with the unique extension property. This extends the landscape of $C^*$-diagonal results beyond simple AH-algebras and connects detailed invariants and standard-map techniques to the diagonalization process in non-simple, NCCW-based inductive limits.
Abstract
This paper establishes the existence of a $C^*$-diagonal in the inductive limit of 1-dimensional NCCW complexes with trivial $K_1$-groups. It also examines some limitations and implications of approximating $^*$-homomorphisms between two such complexes.
