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Orthogonality and complementation in the lattice of subspaces of a finite vector space

Ivan Chajda, Helmut Länger (2022)

Mathematica Bohemica

We investigate the lattice 𝐋 ( 𝐕 ) of subspaces of an m -dimensional vector space 𝐕 over a finite field GF ( q ) with a prime power q = p n together with the unary operation of orthogonality. It is well-known that this lattice is modular and that the orthogonality is an antitone involution. The lattice 𝐋 ( 𝐕 ) satisfies the chain condition and we determine the number of covers of its elements, especially the number of its atoms. We characterize when orthogonality is a complementation and hence when 𝐋 ( 𝐕 ) is orthomodular. For...

Pairs of Clifford algebras of the Hurwitz type

Wiesław Królikowski (1996)

Banach Center Publications

For a given Hurwitz pair [ S ( Q S ) , V ( Q V ) , o ] the existence of a bilinear mapping : C ( Q S ) × C ( Q V ) C ( Q V ) (where C ( Q S ) and C ( Q V ) denote the Clifford algebras of the quadratic forms Q S and Q V , respectively) generated by the Hurwitz multiplication “o” is proved and the counterpart of the Hurwitz condition on the Clifford algebra level is found. Moreover, a necessary and sufficient condition for "⭑" to be generated by the Hurwitz multiplication is shown.

Pairs of k -step reachability and m -step observability matrices

Augusto Ferrante, Harald K. Wimmer (2013)

Special Matrices

Let V and W be matrices of size n × pk and qm × n, respectively. A necessary and sufficient condition is given for the existence of a triple (A,B,C) such that V a k-step reachability matrix of (A,B) andW an m-step observability matrix of (A,C).

Partial choice functions for families of finite sets

Eric J. Hall, Saharon Shelah (2013)

Fundamenta Mathematicae

Let m ≥ 2 be an integer. We show that ZF + “Every countable set of m-element sets has an infinite partial choice function” is not strong enough to prove that every countable set of m-element sets has a choice function, answering an open question from . (Actually a slightly stronger result is obtained.) The independence result in the case where m = p is prime is obtained by way of a permutation (Fraenkel-Mostowski) model of ZFA, in which the set of atoms (urelements) has the structure of a vector...

Currently displaying 1981 – 2000 of 3024