English

Dilations of matricies

Functional Analysis 2015-03-26 v1 Operator Algebras

Abstract

We explore aspects of dilation theory in the finite dimensional case and show that for a commuting nn-tuple of operators T=(T1,...,Tn)T=(T_1,...,T_n) acting on some finite dimensional Hilbert space HH and a compact set XCnX\subset \mathbb{C}^n the following are equivalent: 1. TT has a normal X X-dilation. 2. For any mNm\in \mathbb{N} there exists some finite dimensional Hilbert space KK containing HH and a tuple of commuting normal operators N=(N1,...,Nn)N=(N_1,...,N_n) acting on KK such that q(T)=PHq(N)H q(T)=P_Hq(N)|_H for all polynomials qq of degree at most mm and such that the joint spectrum of NN is contained in XX (where PHP_H is the projection from KK to HH).

Keywords

Cite

@article{arxiv.1503.07334,
  title  = {Dilations of matricies},
  author = {David Cohen},
  journal= {arXiv preprint arXiv:1503.07334},
  year   = {2015}
}
R2 v1 2026-06-22T09:01:41.934Z