Poisson transforms on right-angled Artin monoids
Boyu Li
TL;DR
This work extends Popescu's Cauchy and Poisson transforms to contractive representations of right-angled Artin monoids by introducing the weak Brehmer condition and property (P). It proves the Cauchy transform $C_{r,T}$ is bounded for $0\le r<1$, enabling the Poisson transform $\Phi_T$ and establishing a $*$-regular dilation via Stinespring dilation for representations satisfying these conditions. A key advance is reducing positivity checks to the connected components of the complement graph, with a bound depending on the clique number $\omega(\Gamma)$. In the complete multipartite case, the results recover Popescu's transform and open a path for multivariate operator theory on RA monoids.
Abstract
We introduce the notion of the weak Brehmer's condition and prove that the Cauchy transform for a representation of a right-angled Artin monoid is bounded under such conditions. As a result, we obtain the Poisson transform and $*$-regular dilation for a family of operators that satisfies the weak Brehmer's condition and the property (P). This generalizes Popescu's notion of Cauchy and Poisson transforms for commuting families of row contractions.
