Encontrados 5 documentos, a visualizar página 1 de 1
On the extremal structure of least upper bound norms and their dual
Sá, E. Marques de; Santos, VirgíniaGiven finite dimensional real or complex Banach spaces, E and F, with norms and , we denote by N[mu][nu] the least upper bound norm induced on . Some results are given on the extremal structures of , the unit ball of N[mu][nu], of its polar , and of , which is the polar of the unit ball of the least upper bound norm N[mu]°[nu]°. ; http://www.sciencedirect.com/science/article/B6V0R-4RDBFDR-1/1/816ffee50923a7e...
Fibonacci numbers, alternating parity sequences and faces of the tridiagonal Bi...
Fonseca, C. M. da; Sá, E. Marques deWe determine the number of alternating parity sequences that are subsequences of an increasing m-tuple of integers. For this and other related counting problems we find formulas that are combinations of Fibonacci numbers. These results are applied to determine, among other things, the number of vertices of any face of the polytope of tridiagonal doubly stochastic matrices. ; http://www.sciencedirect.com/scie...
On the number of invariant factors of matrix products
Sá, E. Marques de; Zhang, Yu LinWe prove an inequality relating the number of nontrivial invariant factors of n × n matrices A and B, with those of AB, and get some results on the cases of equality. In particular, we characterize the similarity classes, and , with all eigenvalues in the base field, such that AB is nilpotent for some and . ; http://www.sciencedirect.com/science/article/B6V0R-4F29J0H-6/1/e03b2d17dbee9bd012faadaa2f58683d
On the number of invariant factors of matrix products
Sá, E. Marques de; Zhang YulinIn the first part of the paper we determine bounds for the ranks of certain submatrices of square matrices taken from a prescribed similarity class. Then we discuss the concept of offdiagonal indices (defined in Section 1) which, very roughly speaking, measure, for each given integer s, how far we have to go off the main diagonal of a square matrix, to find an s s nonzero minor. Some open problems are stated.
Electoral cells of largest remainders method
Gouveia, João; Sá, E. Marques deIn an election process, p parties compete for S seats in a parliament. After votes are cast, the electoral result may be thought of as an element x in Rp. Given x, the so-called largest remainders method determines the number ai of seats party i gets in the parliament. The electoral cell determined by (a1,...,ap) is the closure of the set of all results x that determine ai seats for party i, 1<= i<= p. The elec...
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