Let H be a bialgebra. An H-module-algebra is an associative algebra A that is also an H-module such that the multiplication map on A becomes an H-module morphism. This algebraic structure arises often in algebraic topology, quantum groups [11, Chapter V.6], Lie and Hopf algebras theory [3, 16, 19], and group representations [1, Chapter 3]. For example, in algebraic topology, the complex cobordi...

We analyze topological string theory on a two dimensional torus, focusing on symmetries in the matter sector. Even before coupling to gravity, the topological torus has an infinite number of point-like physical observables, which give rise via the BRST descent equations to an infinite symmetry algebra of the model. The point-like observables of ghost number zero form a topological ground ring, ...

In this paper, we study and classify Hilbert space representations of cross product ∗-algebras of the quantized enveloping algebra Uq(e2) with the coordinate algebras O(Eq(2)) of the quantum motion group and O(Cq) of the complex plane, and of the quantized enveloping algebra Uq(su1,1) with the coordinate algebras O(SUq(1, 1)) of the quantum group SUq(1, 1) and O(Uq) of the quantum disc. Invaria...

Let Ω be a circular domain, that is, an open disk with finitely many closed disjoint disks removed. Denote by H(Ω) the Banach algebra of all bounded holomorphic functions on Ω, with pointwise operations and the supremum norm. We show that the topological stable rank of H(Ω) is equal to 2. The proof is based on Suarez’s theorem that the topological stable rank of H(D) is equal to 2, where D is t...

— Let Ω be a circular domain, that is, an open disk with finitely many closed disjoint disks removed. Denote by H(Ω) the Banach algebra of all bounded holomorphic functions on Ω, with pointwise operations and the supremum norm. We show that the topological stable rank of H(Ω) is equal to 2. The proof is based on Suarez’s theorem that the topological stable rank of H(D) is equal to 2, where D is...