Unified min-max and interlacing theorems for linear operators |
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| Authors: | Laura Iglésias Catarina Santa-Clara Fernando C Silva |
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| Institution: | 1. Departamento de Engenharia Mecanica , Instituto Superior de Engenharia de Lisboa , 1949-014 Lisboa, Portugal;2. Centro de Estruturas Lineares e Combinatórias da Universidade de Lisboa , Avenida Professor Gama Pinto, 2, 1649-003 Lisboa, Portugal lica@cii.fc.ul.pt;4. Faculdade de Ciências da Universidade de Lisboa, Departamento de Matemática , Campo Grande, 1749-016 Lisboa, Portugal;5. Centro de álgebra da Universidade de Lisboa , Avenida Professor Gama Pinto, 2, 1649-003 Lisboa, Portugal;6. Centro de Estruturas Lineares e Combinatórias da Universidade de Lisboa , Avenida Professor Gama Pinto, 2, 1649-003 Lisboa, Portugal;7. Faculdade de Ciências da Universidade de Lisboa, Departamento de Matemática , Campo Grande, 1749-016 Lisboa, Portugal |
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| Abstract: | There exist striking analogies in the behaviour of eigenvalues of Hermitian compact operators, singular values of compact operators and invariant factors of homomorphisms of modules over principal ideal domains, namely diagonalization theorems, interlacing inequalities and Courant–Fischer type formulae. Carlson and Sá D. Carlson and E.M. Sá, Generalized minimax and interlacing inequalities, Linear Multilinear Algebra 15 (1984) pp. 77–103.] introduced an abstract structure, the s-space, where they proved unified versions of these theorems in the finite-dimensional case. We show that this unification can be done using modular lattices with Goldie dimension, which have a natural structure of s-space in the finite-dimensional case, and extend the unification to the countable-dimensional case. |
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| Keywords: | Goldie dimension modular lattice eigenvalues invariant factors compact operators |
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