English

Algebraically irreducible representations and structure space of the Banach algebra associated with a topological dynamical system

Operator Algebras 2016-06-22 v2 Functional Analysis

Abstract

If XX is a compact Hausdorff space and σ\sigma is a homeomorphism of XX, then a Banach algebra 1(Σ)\ell^1(\Sigma) of crossed product type is naturally associated with this topological dynamical system Σ=(X,σ)\Sigma=(X,\sigma). If XX consists of one point, then 1(Σ)\ell^1(\Sigma) is the group algebra of the integers. We study the algebraically irreducible representations of 1(Σ)\ell^1(\Sigma) on complex vector spaces, its primitive ideals and its structure space. The finite dimensional algebraically irreducible representations are determined up to algebraic equivalence, and a sufficiently rich family of infinite dimensional algebraically irreducible representations is constructed to be able to conclude that 1(Σ)\ell^1(\Sigma) is semisimple. All primitive ideals of 1(Σ)\ell^1(\Sigma) are selfadjoint, and 1(Σ)\ell^1(\Sigma) is Hermitian if there are only periodic points in XX. If XX is metrisable or all points are periodic, then all primitive ideals arise as in our construction. A part of the structure space of 1(Σ)\ell^1(\Sigma) is conditionally shown to be homeomorphic to the product of a space of finite orbits and T\mathbb T. If XX is a finite set, then the structure space is the topological disjoint union of a number of tori, one for each orbit in XX. If all points of XX have the same finite period, then it is the product of the orbit space X/ZX/\mathbb Z and T\mathbb T. For rational rotations of T\mathbb T, this implies that the structure space is homeomorphic to T2\mathbb T^2.

Keywords

Cite

@article{arxiv.1407.8328,
  title  = {Algebraically irreducible representations and structure space of the Banach algebra associated with a topological dynamical system},
  author = {Marcel de Jeu and Jun Tomiyama},
  journal= {arXiv preprint arXiv:1407.8328},
  year   = {2016}
}

Comments

32 pages. Editorial improvements from the first version, and a few remarks added. Final version, to appear in Advances in Mathematics