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v2007.11.26 - Convex Optimization

v2007.11.26 - Convex Optimization

v2007.11.26 - Convex Optimization

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7.3. THIRD PREVALENT PROBLEM: 4897.3.3 Constrained affine dimension, Problem 3When one desires affine dimension diminished further below what can beachieved via cenv(rank)-minimization as in (1231), spectral projection can beconsidered a natural means in light of its successful application to projectionon a rank ρ subset of the positive semidefinite cone in7.1.4.Yet it is wrong here to zero eigenvalues of −V DV or −V GV or avariant to reduce affine dimension, because that particular method comesfrom projection on a positive semidefinite cone (1168); zeroing thoseeigenvalues here in Problem 3 would place an elbow in the projectionpath (confer Figure 115) thereby producing a result that is necessarilysuboptimal. Problem 3 is instead a projection on the EDM cone whoseassociated spectral cone is considerably different. (5.11.2.3) Proper choiceof spectral cone is demanded by diagonalization of that variable argument tothe objective:7.3.3.1 Cayley-Menger formWe use Cayley-Menger composition of the Euclidean distance matrix to solvea problem that is the same as Problem 3 (1214): (5.7.3.0.1)[ ] [ ]∥ minimize0 1T 0 1T ∥∥∥2D∥ −1 −D 1 −H[ ]F0 1T(1232)subject to rank≤ ρ + 21 −DD ∈ EDM Na projection of H on a generally nonconvex subset (when ρ < N −1) of theEuclidean distance matrix cone boundary rel∂EDM N ; id est, projectionfrom the EDM cone interior or exterior on a subset of its relative boundary(6.6, (1012)).Rank of an optimal solution is intrinsically bounded above and below;[ ] 0 1T2 ≤ rank1 −D ⋆ ≤ ρ + 2 ≤ N + 1 (1233)Our proposed strategy ([ for low-rank ]) solution is projection on that subset0 1Tof a spectral cone λ1 −EDM N (5.11.2.3) corresponding to affine

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