{ "id": "1503.07334", "version": "v1", "published": "2015-03-25T11:17:19.000Z", "updated": "2015-03-25T11:17:19.000Z", "title": "Dilations of matricies", "authors": [ "David Cohen" ], "categories": [ "math.FA", "math.OA" ], "abstract": "We explore aspects of dilation theory in the finite dimensional case and show that for a commuting $n$-tuple of operators $T=(T_1,...,T_n) $ acting on some finite dimensional Hilbert space $H$ and a compact set $X\\subset \\mathbb{C}^n$ the following are equivalent: 1. $T$ has a normal $ X$-dilation. 2. For any $m\\in \\mathbb{N}$ there exists some finite dimensional Hilbert space $K$ containing $H$ and a tuple of commuting normal operators $N=(N_1,...,N_n)$ acting on $K$ such that $$ q(T)=P_Hq(N)|_H$$ for all polynomials $q$ of degree at most $m$ and such that the joint spectrum of $N$ is contained in $X$ (where $P_H$ is the projection from $K$ to $H$).", "revisions": [ { "version": "v1", "updated": "2015-03-25T11:17:19.000Z" } ], "analyses": { "keywords": [ "finite dimensional hilbert space", "finite dimensional case", "dilation theory", "joint spectrum", "commuting normal operators" ], "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable" } } }