Type 1 noncommutative Borsuk–Ulam conjecture for compact group actions

About 7 years old · traced to

Let GG be a nontrivial compact group acting freely on a unital C∗C^*-algebra AA. Define the join

A⊛C(G)={f∈C([0,1],A⊗C(G)):f(0)∈C⊗C(G), f(1)∈A⊗C}.A\circledast C(G)=\{f\in C([0,1],A\otimes C(G)): f(0)\in \mathbb{C}\otimes C(G),\ f(1)\in A\otimes\mathbb{C}\}.

Equip A⊛C(G)A\circledast C(G) with the diagonal action of GG. Type 1 noncommutative Borsuk–Ulam conjecture. There is no equivariant, unital ∗*-homomorphism

ϕ:A→A⊛C(G).\phi:A\to A\circledast C(G).

This is the compact-group subcase of the Type 1 noncommutative Borsuk–Ulam conjecture, originally formulated for coactions of compact quantum groups. It asserts that a free action cannot admit an equivariant unital map from AA to its join with the acting group.

References

Primary source

Alexandru Chirvasitu, Benjamin Passer and Mariusz Tobolski, “Equivariant Dimensions of Graph C*-algebras”, arXiv:1907.10010 (2020).

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.