C*-envelopes of semicrossed products by lattice ordered abelian semigroups

Abstract

A semicrossed product is a non-selfadjoint operator algebra encoding the action of a semigroup on an operator or C*-algebra. We prove that, when the positive cone of a discrete lattice ordered abelian group acts on a C*-algebra, the C*-envelope of the associated semicrossed product is a full corner of a crossed product by the whole group. By constructing a C*-cover that itself is a full corner of a crossed product, and computing the Shilov ideal, we obtain an explicit description of the C*-envelope. This generalizes a result of Davidson, Fuller, and Kakariadis from ${\mathbb{Z}}_{+}^n$ to the class of all discrete lattice ordered abelian groups.

36 pages. Updated to reflect published version in JFA. Minor typos fixed throughout and new Corollary 3.18 (nonunital case) and Subsection 6.1 (simplicity of the C*-envelope) added