Identity conjecture for the unitary-conjugation descent construction

Let AθA_\theta be the irrational rotation algebra, let GAθ\mathcal{G}_{A_\theta} be its unitary conjugation groupoid, and let uMn(Aθ)u\in M_n(A_\theta) be invertible. Consider the proposed maps from the class of uu through equivariant KKKK-theory, groupoid descent, and the Morita identification:

[u]K1(Aθ)liftKKGAθ1(Aθ,C)descK1(C(GAθ))K1(Aθ).[u]\in K_1(A_\theta)\xrightarrow{\mathrm{lift}}KK^1_{\mathcal{G}_{A_\theta}}(A_\theta,\mathbb C)\xrightarrow{\mathrm{desc}}K_1(C^*(\mathcal{G}_{A_\theta}))\xrightarrow{\cong}K_1(A_\theta).

Identity conjecture for the unitary-conjugation descent construction. The resulting class coincides with the original class [u][u]. In particular, the lift map is injective and its image consists exactly of those equivariant KKKK-classes fixed by the natural automorphisms.

The text describes this as a fundamental conjecture planned for future work, intended to give an explicit geometric realization of K1(Aθ)K_1(A_\theta) through the unitary conjugation groupoid.

Sources & referencesView supporting material

Primary source

Shih-Yu Chang, “The Unitary Conjugation Groupoid as a Universal Mediator of the Baum–Connes Assembly Map”, arXiv:2603.22162 (2026).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.