Results 21 to 30 of about 218 (36)

Inverses and eigenvalues of diamondalternating sign matrices

open access: yesSpecial Matrices, 2014
An n × n diamond alternating sign matrix (ASM) is a (0, +1, −1)-matrix with ±1 entries alternatingand arranged in a diamond-shaped pattern. The explicit inverse (for n even) or generalized inverse (for nodd) of a diamond ASM is derived.
Catral Minerva   +3 more
doaj   +1 more source

Rationality of the zeta function of the subgroups of abelian $p$-groups

open access: yes, 2017
Given a finite abelian $p$-group $F$, we prove an efficient recursive formula for $\sigma_a(F)=\sum_{\substack{H\leq F}}|H|^a$ where $H$ ranges over the subgroups of $F$.
Ramaré, Olivier
core   +2 more sources

Small-span Hermitian matrices over quadratic integer rings

open access: yes, 2013
Building on the classification of all characteristic polynomials of integer symmetric matrices having small span (span less than 4), we obtain a classification of small-span polynomials that are the characteristic polynomial of a Hermitian matrix over ...
Greaves, Gary
core   +1 more source

Eulerian polynomials as moments, via exponential Riordan arrays [PDF]

open access: yes, 2011
Using the theory of exponential Riordan arrays and orthogonal polynomials, we demonstrate that the "descending power" Eulerian polynomials, and their once shifted sequence, are moment sequences for simple families of orthogonal polynomials, which we ...
Barry, Paul
core   +3 more sources

Commutators and Anti-Commutators of Idempotents in Rings

open access: yes, 2018
We show that a ring $\,R\,$ has two idempotents $\,e,e'\,$ with an invertible commutator $\,ee'-e'e\,$ if and only if $\,R \cong {\mathbb M}_2(S)\,$ for a ring $\,S\,$ in which $\,1\,$ is a sum of two units. In this case, the "anti-commutator" $\,ee'+e'e\
Khurana, Dinesh, Lam, T. Y.
core   +1 more source

On (k1A1, k2A2, k3A3)-Edge Colourings in Graphs and Generalized Jacobsthal Numbers

open access: yesAnnales Mathematicae Silesianae
In this paper we introduce a new kind of generalized Jacobsthal numbers in a distance sense. We give the identities and matrix representations for them and their connections with the Fibonacci and the Pell numbers. We also describe the interpretations of
Piejko Krzysztof, Trojnar-Spelina Lucyna
doaj   +1 more source

The number of rational points of some classes of algebraic varieties over finite fields

open access: yesOpen Mathematics
Let Fq{{\mathbb{F}}}_{q} be the finite field of characteristic pp and Fq*=Fq\{0}{{\mathbb{F}}}_{q}^{* }\left={{\mathbb{F}}}_{q}\backslash \left\{0\right\}.
Zhu Guangyan   +3 more
doaj   +1 more source

The Maximum Order of Reduced Square(0, 1)-Matrices with a Given Rank [PDF]

open access: yes
We look for the maximum order of a square (0, 1)-matrix A with a fixed rank r, provided A has no repeated rows or columns. If A is the adjacency matrix of a graph, Kotlov and Lovász [J. Graph Theory 23, 1996] proved that the maximum order equals Θ(2r/2).
Haemers, W.H., Peeters, M.J.P.
core   +1 more source

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