Operator algebras of monomial ideals in noncommuting variables

Evgenios T.A. Kakariadis, Orr Moshe Shalit

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We study operator algebras arising from monomial ideals in the ring of polynomials in noncommuting variables, through the apparatus of subproduct systems and C*-correspondences. We provide a full comparison amongst the related operator algebras. For our analysis we isolate a partially defined dynamical system, to which we refer as the quantised dynamics of the monomial ideal. In addition we revisit several previously considered constructions. These include Matsumoto's subshift C*-algebras, as well as the tensor and the Pimsner algebras associated with dynamical systems or graphs. We sort out the various relations by giving concrete conditions and counterexamples that orientate the operator algebras of our context. It appears that the boundary C*-algebras do not arise as the quotient with the compact operators unconditionally. We establish a dichotomy to this effect by examining the resulting tensor algebras. We identify their boundary representations, we analyse their C*-envelopes, and we give criteria for hyperrigidity. Moreover we completely classify them in terms of the data provided by the monomial ideals. For tensor algebras of C*-correspondences and bounded isomorphisms this is achieved up to the level of local conjugacy (in the sense of Davidson and Roydor) for the quantised dynamics. For tensor algebras of subproduct systems and algebraic isomorphisms this is achieved up to the level of equality of monomial ideals modulo permutations of the variables. In the process we accomplish more in different directions. Most notably we show that tensor algebras form a complete invariant for isomorphic (resp. similar) subproduct systems of homogeneous ideals up to isometric (resp. bounded) isomorphisms. The results on local conjugacy are obtained via an alternative proof of the breakthrough result of Davidson and Katsoulis on piecewise conjugate systems. For our purposes we use appropriate compressions of the Fock representation. We then apply this alternative proof locally for the partially defined quantised dynamics. In this way we avoid the topological graphs machinery and pave the way for further applications. These include operator algebras of dynamical systems over commuting contractions or over row commuting contractions.

Original languageEnglish
Pages (from-to)738-813
Number of pages76
JournalJournal of Mathematical Analysis and Applications
Issue number1
StatePublished - 1 Apr 2019
Externally publishedYes


  • C*-correspondences
  • C*-envelope
  • Fock space algebras
  • Rigidity
  • Subproduct systems

ASJC Scopus subject areas

  • Analysis
  • Applied Mathematics


Dive into the research topics of 'Operator algebras of monomial ideals in noncommuting variables'. Together they form a unique fingerprint.

Cite this