8,483 reputation
21745
bio website quoll.uwaterloo.ca
location waterloo
age 66
visits member for 5 years, 7 months
seen 1 hour ago
Professor at University of Waterloo in C&O

1d
reviewed Close how to solve a linear equation (Ax-b)T- lamda(c)?
1d
reviewed Close How to show that the mapping A is linear ?
2d
reviewed Close system of linear equations
May
27
answered Graph classes which are not perfect but the stability number = clique cover numer?
May
23
reviewed Close Searching for $C^*$
May
13
reviewed Leave Open Average degree of neighbors in a simple graph (-> Friendship paradox)
Apr
22
reviewed Close Anick resolution
Apr
16
reviewed Leave Open Notation for the all-ones vector
Apr
11
reviewed Close Integral closure of an ideal
Apr
11
awarded  graph-theory
Apr
10
comment Request for examples of 4-regular, non-planar, girth at least 5 graphs
@gordonRoyle: I was thinking there might be examples on fewer than 19 vertices?
Apr
10
answered Request for examples of 4-regular, non-planar, girth at least 5 graphs
Apr
7
comment About the second largest adjacency eigenvalue of Abelian Cayley graphs
The matrix is $d\times m$ (say). There are $2^d$ binary vectors and they form a group of order $2^d$. The graphs we get is a Cayley graph for this group, with valency $m$. The problem is to compute the eigenvalues in time polynomial in $n$.
Apr
7
comment About the second largest adjacency eigenvalue of Abelian Cayley graphs
The vertices are binary vectors. Two vertices are adjacent if their difference is a column of the given matirx.
Apr
1
reviewed Close If $(X_n+Y_n)$ has bounded variance, is the same true for $(X_n)$ and $(Y_n)$?
Apr
1
reviewed Leave Open Dissolution of Tensors
Mar
26
reviewed Leave Open Lovasz's Path removal conjecture
Mar
24
revised About the upper bound on the roots of the matching polynomial
removed ambiguity, fixed typo
Mar
24
comment About the upper bound on the roots of the matching polynomial
@user6818: I have edited my answer. I wrote "gives", which is ambiguous, now it's "divides".
Mar
23
comment About the upper bound on the roots of the matching polynomial
The reason your "following statement" is not in the paper is that it is not true. The paper shows that given a graph $G$ thrre is a tree $T$ such that the matching polynomial of $G$ divides the matching polynomial of $T$. But the matching polynomial of a tree is equal to its characteristic polynomial and the graph and the tree have the same maximum valency, so standard eigenvalue bounds on the tree give the bound on the zeros of matching polynomial of $G$.