Finitely generated weakly monotone C*-algebra
Maria Elena Griseta, Janusz Wysoczański
TL;DR
The paper characterizes the C*-algebra generated by finitely many annihilation operators on the weakly monotone Fock space as a quotient of a Cuntz-Krieger algebra $O_A$ associated with a lower-triangular incidence matrix $A$, via the ideal generated by $a_0 - a_0^*a_0$ where $a_0$ is the vacuum projection. It then identifies and analyzes a maximal abelian subalgebra (MASA) given by the diagonal, describing its spectrum as a subset of $[0,1]^n$ with a discrete part and a boundary. The main contributions include a faithful representation of the weakly monotone algebra, a precise quotient construction, and a detailed, geometric description of the MASA spectrum, including explicit cases for $n=2$ and $n=3$. These results connect weakly monotone operator algebras to graph/Cuntz-Krieger frameworks and provide structural data valuable for representation theory and potential applications in quantum probability.
Abstract
We consider the $C^*$-algebra generated by finitely many annihilation operators acting on the weakly monotone Fock space, and we call it weakly monotone $C^*$-algebra. We give an abstract representation for this algebra, showing that it is isomorphic to a suitable quotient of a Cuntz-Krieger $C^*$-algebra $\mathcal{O}_A$ corresponding to a suitable matrix $A$. Furthermore, we show that the diagonal subalgebra of the weakly monotone $C^*$-algebra is a MASA and we give the detailed description of its Gelfand spectrum.
