Abstract
The approximation of a multivector by a decomposable one is a distance-optimization problem between the multivector and the Grassmann variety of lines in a projective space. When the multivector diverges from the Grassmann variety, then the approximate solution sought is the worst possible. In this paper, it is shown that the worst solution of this problem is achieved, when the eigenvalues of the matrix representation of a related two-vector are all equal. Then, all these pathological points form a projective variety. We derive the equation describing this projective variety, as well as its maximum distance from the corresponding Grassmann variety. Several geometric and algebraic properties of this extremal variety are examined, providing a new aspect for the Grassmann varieties and the respective projective spaces.
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Notes
\((\hat{\underline{z}, \underline{x}})\) denotes the angle between multivectors \(\underline{z}\) and \(\underline{x}\).
References
Eckart, C., Young, G.: The approximation of one matrix by another of lower rank. Psychometrika 1, 211–218 (1936)
Kolda, T., Bader, B.: Tensor decompositions and applications. SIAM Rev. 51(3), 455–500 (2009)
Landsberg, J.M.: Tensors: Geometry and Applications. AMS, Providence, Rhode Island (2012)
Hodge, W., Pedoe, D.: Methods of Algebraic Geometry, vol. 2. Cambridge University Press, Cambridge (1952)
Marcus, M.: Finite Dimensional Multilinear Algebra, Parts 1 and 2. Marcel Deker, New York (1973)
Karcanias, N., Leventides, J.: Grassmann matrices, determinantal assignment problem and approximate decomposability. In: Proceedings of Third IFAC Symposium on Systems Structure and Control Symposium (SSSC 07), 17–19 October, Foz do Iguacu, Brazil (2007)
Leventides, J., Petroulakis, G., Karcanias, N.: The approximate determinantal assignment problem. Linear Algebra Appl. 461, 139–162 (2014)
Kanatani, K.: Statistical Optimization for Geometric Computation: Theory and Practice. Dover Publications, NY (2005)
Schmidt, W.M.: Diophantine Approximation. Springer, Berlin (1996)
Golub, G.H., Hoffmann, A., Stewart, G.W.: A generalization of the Eckart–Young–Mirsky matrix approximation theorem. Linear Algebra Appl. 88(89), 317–327 (1987)
Marcus, M., Minc, H.: A Survey of Matrix Theory and Matrix Inequalities. Allyn and Bacon, Boston (1964)
Eisenbud, D., Grayson, D.R., Stillman, M., Sturmfels, B.: Computations in Algebraic Geometry with Macaulay 2. Springer, Berlin (2001)
Mirsky, L.: A trace inequality of John von Neumann. Monatsh. Math. 79(4), 303–306 (1975)
Fulton, W., Hansen, J.: A connectedness theorem for projective varieties, with applications to intersections and singularities of mappings. Ann. Math. 110, 159–166 (1979)
Mumford, D.: Varieties defined by quadratic equations. Questions on Algebraic Varieties, Corso CIME, Rome, pp. 30–100 (1969)
Ciliberto, C., Geramita, A.V., Harbourne, B., Miro-Roig, R.M., Ranestad, K. (eds.): Projective Varieties with Unexpected Properties. Walter de Gruyter Inc., Berlin (2005)
Kozlov, S.E.: Geometry of real Grassmann manifolds-V. J. Math. Sci. 104(4), 1318–1328 (2001)
Prajna, P., Papachristodoulou, A., Parrilo, P.: SOSTOOLS: Sum of Squares Optimization Toolbox for Matlab-User’s Guide. Eprints for the optimization community (2002)
Acknowledgments
This article is supported by Marie Curie FP7-PEOPLE-2012-IEF 329084 A-DAP. We would also like to thank the anonymous referees for the valuable and helpful suggestions they made for the improvement of this article and their remarks with respect to the projective and the affine space as well as the determinantal properties of the extremal varieties.
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Leventides, J., Petroulakis, G. & Karcanias, N. Distance Optimization and the Extremal Variety of the Grassmann Variety. J Optim Theory Appl 169, 1–16 (2016). https://doi.org/10.1007/s10957-015-0840-7
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DOI: https://doi.org/10.1007/s10957-015-0840-7
Keywords
- Distance geometry problems
- Optimization
- Approximations
- Projective varieties
- Sums of squares and representations