Simon Fraser University

Abstract: Graphs and co-graphs (their matroid duals) dominate the structure of Totally Unimodular Matrices, real matrices whose subdeterminants lie in {0, +1, -1}. Thus some results about graph colorings and flows have common generalizations...

Abstract: Given a binary matroid $M$ represented by a binary matrix $A$ we can consider the binary matroid represented by $A$ plus an extra binary row$\\Sigma$. We call this a signed matroid and say that $(M,\\Sigma)$ is arepresentation of the signed...

Abstract: Aquantum walk is a quantum process on graph. It is proposed by Emms, Hancock, Severini and Wilson in 2006, that the spectrum of a matrix based on theamplitudes of walks in the quantum walk, distinguishes strongly regular graphs. We will try...

Abstract: Given a set of directions S \\subseteq {0,1,-1}^2 \\setminus {(0,0)}, we wish to count the number of lattice walks of length n on S restricted to the quarter plane. For most sets S, this amountsto a full generation of all walks of length n...

Abstract: It is a long standing open problem in algebraic combinatorics to compute the Kronecker coefficients of the symmetric group using a combinatorial rule. In this talk I will discuss explicit combinatorial formulae (for 5 new cases) for...

Abstract: We consider two classical number theoretic problems that may seem quiteunrelated: * What is the power of 2 dividing the class number of Q(sqrt(-n))* Which n are congruent numbers (n called congruent if it occurs as the area of a right...