University of Manitoba

There has been extensive study of diagonalization of matrices. Diagonalization can be viewed as using a similarity transform to concentrate the magnitude of all entries within as small a subset of entries as possible. We motivate and present results...

Let G = (V, E) be a simple graph of order n. The adjacency matrix of G is denoted by A(G) = [a_ij], where a_ij=1 if {v_i ,v_j} ∈ E and a_ij=0, otherwise. The diagonal matrix of degrees of G, D(G) = [d_ij], is defined by d_ii=d(v_i), and d_ij=0, ∀ i...

Let us ask: What is a "strong" matrix property and why is such a property useful for studying eigenvalues of graphs? During this talk we will attempt to address both questions above by first wandering through some of the developed strong matrix...

Let M be a Hermitian matrix associated to a graph X on n vertices. For any time t \geq 0, the transition matrix of the continuous quantum walk on X relative to M at time t is given by U(t)=exp(itM). For two vertices a and b of X, if there is some...

The signs of the entries of a real matrix can give insight into the eigenvalues of the matrix. A well-known example is the Perron Frobenius theorem for matrices that have no negative entries. As an inverse eigenvalue problem, one can ask for the...

For a fixed $d \in \mathbb{N}$, the non-commutative (nc) universe $\mathbb{M}^d$ is defined as the graded (disjoint) union of $d$-tuples of $n \times n$ (complex) matrices over $n \in \mathbb{N}$. A function $f : \mathbb{M}^d \to \mathbb{M}^1$ is...

In combinatorial matrix theory (CMT) one studies properties of combinatorial matrices, i.e., matrices with entries 0, 1 and -1. For instance, permutation matrices, i.e., (0,1)-matrices with exactly one 1 in every row and column, are interesting...

Many quantum search algorithms are equivalent to coined quantum walks that start from a uniform superposition of arcs and get very close to a state that "concentrates on" some marked vertex. In this talk, we consider a related problem: if we start...

A sign pattern (matrix) has entries in {+, -, 0}. We investigate eigenvalue properties of a sign pattern of order 2n where two of the blocks are prescribed sign patterns of order n, and the other two (order n) blocks are the positive diagonal sign...

The distance matrix of a graph records the length of the shortest path between any two vertices. Graham and Pollak found that when the underlying graph is a tree, the determinant of the distance matrix satisfies a nice, simple formula. In particular...