Now showing items 21-33 of 33

• #### An Erdos-Ko-Rado theorem for the derangement graph of PGL(2,q) acting on the projective plane ﻿

(SIAM Journal on Discrete Mathematics, 2014)
Let G = PGL(2, q) be the projective general linear group acting on the projec- tive line P_q. A subset S of G is intersecting if for any pair of permutations \pi and \sigma in S, there is a projective point p in P_q such ...
• #### An Erdős-Ko-Rado theorem for the derangement graph of $$PGL_3(q)$$ acting on the projective plane ﻿

(SIAM J. Discrete Math. 28, 2014)
In this paper we prove an Erdős-Ko-Rado-type theorem for intersecting sets of permutations. We show that an intersecting set of maximal size in the projective general linear group $$PGL_3(q)$$, in its natural ...
• #### Performance enhancement of doubling algorithms for a class of complex nonsymmetric algebraic Riccati equations ﻿

(Oxford University Press, 2014)
A new class of complex nonsymmetric algebraic Riccati equations has been studied by Liu and Xue (SIAM J. Matrix Anal. Appl., 33 (2012), 569-596), which is related to the M-matrix algebraic Riccati equations. Doubling ...
• #### The principal rank characteristic sequence over various fields ﻿

(Elsevier, 2014)
Given an n-by-n matrix, its principal rank characteristic sequence is a sequence of length n + 1 of 0s and 1s where, for k = 0; 1,..., n, a 1 in the kth position indicates the existence of a principal submatrix of rank ...
• #### Intersecting generalized permutations ﻿

(2014-01-21)
• #### C.V. ﻿

(2014-01-21)
• #### A convergence result for matrix Riccati differential equations associated with M-matrices ﻿

(2014-04-22)
The initial value problem for a matrix Riccati differential equation associated with an $M$-matrix is known to have a global solution $X(t)$ on $[0, \infty)$ when $X(0)$ takes values from a suitable set of nonnegative ...
• #### The maximum nullity of a complete edge subdivision graph is equal to it zero forcing number ﻿

(International Linear Algebra Society, 2014-06)
Barrett et al. asked in [W. Barrett et al. Minimum rank of edge subdivisions of graphs. Electronic Journal of Linear Algebra, 18:530–563, 2009.], whether the maximum nullity is equal to the zero forcing number for all ...
• #### On the complexity of the positive semidefinite zero forcing number ﻿

(Elsevier, 2015)
The positive semidefinite zero forcing number of a graph is a graph parameter that arises from a non-traditional type of graph colouring and is related to a more conventional version of zero forcing. We establish a relation ...
• #### The enhanced principal rank characteristic sequence ﻿

(Elsevier, 2015)
The enhanced principal rank characteristic sequence (epr-sequence) of a symmetric n ×n matrix is a sequence from A,S, or N according as all, some, or none of its principal minors of order k are nonzero. Such sequences give ...
• #### The enhanced principal rank characteristic sequence for skew-symmetric matrices ﻿

(Elsevier, 2015-08-15)
The enhanced principal rank characteristic sequence (epr-sequence) was originally defined for an n ×n real symmetric matrix or an n ×n Hermitian matrix. Such a sequence is defined to be l1l2···ln where lk is A,S, or N ...
• #### An Erdős-Ko-Rado theorem for finite $$2$$-transitive groups ﻿

(European Journal of Combinatorics, 2016)
We prove an analogue of the classical Erdős-Ko-Rado theorem for intersecting sets of permutations in finite $$2$$-transitive groups. Given a finite group $$G$$ acting faithfully and $$2$$-transitively on the set ...
• #### MIKL´ OS-MANICKAM-SINGHI CONJECTURES ON PARTIAL GEOMETRIES ﻿

(2016-06)
In this paper we give a proof of the Mikl´os-Manickam-Singhi (MMS) conjecture for some partial geometries. Specifically, we give a condition on partial geometries which implies that the MMS conjecture holds. Further, ...