Spectrahedral Containment and Operator Systems with finite-dimensional Realization
Tobias Fritz, Tim Netzer, and Andreas Thom
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Submission date: 27. Sep. 2016 (revised version: October 2017)
published in: SIAM journal on applied algebra and geometry, 1 (2017) 1, p. 556-574
DOI number (of the published article): 10.1137/16M1100642
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Containment problems for polytopes and spectrahedra appear in various applications, such as linear and semideﬁnite programming, combinatorics, convexity and stability analysis of diﬀerential equations. This paper explores the theoretical background of a method proposed by Ben-Tal and Nemirovksi [?]. Their method provides a strengthening of the containment problem, that is algorithmically well tractable. To analyze this method, we study abstract operator systems, and investigate when they have a ﬁnite-dimensional concrete realization. Our results give some profound insight into their approach. They imply that when testing the inclusion of a ﬁxed polyhedral cone in an arbitrary spectrahedron, the strengthening is tight if and only if the polyhedral cone is a simplex. This is true independent of the representation of the polytope. We also deduce error bounds in the other cases, simplifying and extending recent results by various authors.