Search
Now showing items 1-29 of 29
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2023)
Matrix majorization is a generalization of the classical majorization for vectors. We study several basic questions concerning matrix majorization for (0;±1)-matrices, i.e., matrices whose entries are restricted to 0, 1 ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2023)
Permutation graphs are graphs associated with permutations where edges represent inversions. We study different classes of permutation graphs and isomorphic permutation graphs. A complete answer of a basic isomorphism ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We introduce a generalization of alternating sign matrices (ASMs) called multiASMs and develop some of their properties. Classes of multiASMs with specified row and column sum vectors R and S extend the classes of ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
The bottleneck matrix M of a rooted tree T is a combinatorial object encoding the spatial distribution of the vertices with respect to the root. The spectral radius of M, known as the Perron value of the rooted tree, is ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
Sign-restricted matrices (SRMs) are (0,±1)-matrices where, ignoring 0's, the signs in each column alternate beginning with a +1 and all partial row sums are nonnegative. The most investigated of these matrices are the ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
We study sign-restricted matrices (SRMs), a class of rectangular (0, ±1)-matrices generalizing the alternating sign matrices (ASMs). In an SRM each partial column sum, starting from row 1, equals 0 or 1, and each partial ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
Abstract For a permutation π , and the corresponding permutation matrix, we introduce the notion of discrete derivative , obtained by taking differences of successive entries in π . We characterize the possible derivatives ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
This paper is concerned with properties of permutation matrices and alternating sign matrices (ASMs). An ASM is a square (0,±1)-matrix such that, ignoring 0’s, the 1’s and −1’s in each row and column alternate, beginning ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)
Let G be an undirected simple graph. The signless Laplacian spread of G is defined as the maximum distance of pairs of its signless Laplacian eigenvalues. This paper establishes some new bounds, both lower and upper, for ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)
Let A be an n × n (0, ∗)-matrix, so each entry is 0 or ∗. An A-interval matrix is a (0, 1)-matrix obtained from A by choosing some ∗’s so that in every interval of consecutive ∗’s, in a row or column of A, exactly one ∗ ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)
We introduce a new majorization order for classes (sets) of matrices which generalizes several existing notions of matrix majorization. Roughly, the notion says that every matrix in one class is majorized by some matrix ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)
We investigate the Smith Normal Form (SNF) of alternating sign matrices (ASMs) and related matrices of 0’s and 1’s ((0, 1)-matrices). We identify certain classes of ASMs and (0, 1)-matrices whose SNFs are (0, 1)-matrices. ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
An alternating sign matrix , or ASM, is a (0,±1)(0,±1)-matrix where the nonzero entries in each row and column alternate in sign, and where each row and column sum is 1. We study the convex cone generated by ASMs of order ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
The algebraic connectivity a(G) of a graph G is an important parameter, defined as the second smallest eigenvalue of the Laplacian matrix of G. If T is a tree, a(T) is closely related to the Perron values (spectral radius) ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
We consider the problem of finding a maximum k-regular induced subgraph of a graph G. Theoretical results are established to compare upper bounds obtained from different techniques, including bounds from quadratic programming, ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2016)
The Bruhat order is defined in terms of an interchange operation on the set of permutation matrices of order n which corresponds to the transposition of a pair of elements in a permutation. We introduce an extension of ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2016)
A matrix with a nonzero nonnegative vector in its null space is called central . We study classes of central matrices having zero column sums. The study is motivated by an engineering application concerning induction ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)
A matrix of the form A = BBT where B is nonnegative is called completely positive (CP). Berman and Xu (2005) investigated a subclass of CP-matrices, called f0, 1g-completely positive matrices. We introduce a related concept ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2013)
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2013)
This is an Author's Accepted Manuscript of an article published in Linear and Multilinear Algebra
Volume 61, Issue 3, 2013. Published online: 07 Jun 2012. Copyright Taylor & Francis, available online
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2006)
Starting with a problem in wireless telecommunication, we are led to study the multiple knapsack problem with assignment restrictions. This problem is NP-hard. We consider special cases and their computational complexity. ...
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2004)
An Elsevier Open Archive article.
NOTICE: this is the author’s version of a work that was accepted for publication in Linear Algebra and its Applications. Changes resulting from the publishing process, such as peer ...