Regular Dilation on Graph Products of $\mathbb{N}$

TL;DR

This paper extends the concept of regular dilation to graph products of natural numbers, unifying key results in dilation theory and characterizing when representations have isometric Nica-covariant dilations.

Contribution

It introduces a new framework for regular dilation on graph products of , unifies existing dilation results, and characterizes -representations with isometric Nica-covariant dilations.

Findings

Unified Brehmer's and Frazho-Bunce-Popescu's dilation results.

Characterized -representations with isometric Nica-covariant dilations.

Connected the new results with Popescu's earlier work.

Abstract

We extended the definition of regular dilation to graph products of $\mathbb{N}$, which is an important class of quasi-lattice ordered semigroups. Two important results in dilation theory are unified under our result: namely, Brehmer's regular dilation on $\mathbb{N}^k$ and Frazho-Bunce-Popescu's dilation of row contractions. We further show that a representation of a graph product has an isometric Nica-covariant dilation if and only if it is $\ast$-regular. A special case of our result was considered by Popescu, and we studied the connection with Popescu's work.