Abstract:We consider two notions for the representations of convex cones: G-representation and lifted-G-representation. The former represents a convex cone as a slice of another; the latter allows in addition, the usage of auxiliary variables in the representation. We first study the basic properties of these representations. We show that some basic properties of convex cones are invariant under one notion of representation but not the other. In particular, we prove that lifted-G-representation is closed under duality … Show more
“…Our tests show that the approach based on a quadratic formulation is better conditioned and more efficient that the approach based on a linearization. These tests confirm the theoretical results on the conditioning of different barriers, (Güler and Tunçel 1998;Chua and Tunçel 2008).…”
Section: Introductionsupporting
confidence: 78%
“…These tests provide empirical evidence for the theoretical comparison results on different barriers given in Güler and Tunçel (1998), Chua and Tunçel (2008). The results in these references show that the central path is distorted due to the I in the linear formulation constraint.…”
We study Semidefinite Programming, SDP , relaxations for Sensor Network Localization, SNL, with anchors and with noisy distance information. The main point of the paper is to view SNL as a (nearest) Euclidean Distance Matrix, EDM, completion problem that does not distinguish between the anchors and the sensors. We show that there are advantages for using the well studied EDM model. In fact, the set of anchors simply corresponds to a given fixed clique for the graph of the EDM problem.We next propose a method of projection when large cliques or dense subgraphs are identified. This projection reduces the size, and improves the stability, of the relaxation. In addition, by viewing the problem as an EDM completion problem, we are able to derive a new approximation scheme for the sensors from the SDP approximation. This yields, on average, better low rank approximations for the low dimensional realizations. This further emphasizes the theme that SNL is in fact just an EDM problem.We solve the SDP relaxations using a primal-dual interior/exterior-point algorithm based on the Gauss-Newton search direction. By not restricting iterations to the interior, we usually get lower rank optimal solutions and thus, better approximations for the SNL problem. We discuss the relative stability and strength of two formulations and the corresponding algorithms that are used. In particular, we show that the quadratic formulation arising from the SDP relaxation is better conditioned than the linearized form that is used in the literature.
“…Our tests show that the approach based on a quadratic formulation is better conditioned and more efficient that the approach based on a linearization. These tests confirm the theoretical results on the conditioning of different barriers, (Güler and Tunçel 1998;Chua and Tunçel 2008).…”
Section: Introductionsupporting
confidence: 78%
“…These tests provide empirical evidence for the theoretical comparison results on different barriers given in Güler and Tunçel (1998), Chua and Tunçel (2008). The results in these references show that the central path is distorted due to the I in the linear formulation constraint.…”
We study Semidefinite Programming, SDP , relaxations for Sensor Network Localization, SNL, with anchors and with noisy distance information. The main point of the paper is to view SNL as a (nearest) Euclidean Distance Matrix, EDM, completion problem that does not distinguish between the anchors and the sensors. We show that there are advantages for using the well studied EDM model. In fact, the set of anchors simply corresponds to a given fixed clique for the graph of the EDM problem.We next propose a method of projection when large cliques or dense subgraphs are identified. This projection reduces the size, and improves the stability, of the relaxation. In addition, by viewing the problem as an EDM completion problem, we are able to derive a new approximation scheme for the sensors from the SDP approximation. This yields, on average, better low rank approximations for the low dimensional realizations. This further emphasizes the theme that SNL is in fact just an EDM problem.We solve the SDP relaxations using a primal-dual interior/exterior-point algorithm based on the Gauss-Newton search direction. By not restricting iterations to the interior, we usually get lower rank optimal solutions and thus, better approximations for the SNL problem. We discuss the relative stability and strength of two formulations and the corresponding algorithms that are used. In particular, we show that the quadratic formulation arising from the SDP relaxation is better conditioned than the linearized form that is used in the literature.
“…These tests provide empirical evidence for the theoretical comparison results on different barriers given in [15,9]. The results in these references show that the central path is distorted due to the I in the linear formulation constraint.…”
Section: Measure 1: Objective Function With Different Anchorsmentioning
Abstract. Utilizing dual descriptions of the normal cone of convex optimization problems in conic form, we characterize the vertices of semidefinite representations arising from Lovász theta body, generalizations of the elliptope and related convex sets. Our results generalize vertex characterizations due to Laurent and Poljak from the 1990's. Our approach also leads us to nice characterizations of strict complementarity and to connections with some of the related literature.
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