All Questions
Tagged with adjacency-matrices co.combinatorics
5 questions
5
votes
0
answers
513
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Computing adjacency matrix eigenvalues by counting closed walks
Let $G$ be a finite undirected graph. A closed walk in $G$ is a walk from any vertex of $G$ to itself. It is relatively straightforward to show that the total number of closed walks of length $k$ in $...
24
votes
6
answers
2k
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Factorization of the characteristic polynomial of the adjacency matrix of a graph
Let $G$ be a regular graph of valence $d$ with finitely many vertices, let $A_G$ be its adjacency matrix, and let $$P_G(X)=\det(X-A_G)\in\mathbb{Z}[X]$$ be the adjacency polynomial of $G$, i.e., the ...
4
votes
1
answer
207
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Digraphs with unique walk of length $k$ between any two vertices
Let $G$ be a digraph such that there is an unique directed walk of length $k$ between any two vertices.
Equivalently, if $A$ is the adjacency matrix of $G$, then $A^k$ is the matrix with all entries $...
1
vote
1
answer
847
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Do there exist graphs whose adjacency matrix is positive semi-definite? [closed]
If so, could you provide examples and specify the conditions under which this occurs? Thank you in advance
2
votes
2
answers
234
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Adjacency matrix of total graph
Is there a nice way of relating the adjacency, incidence , Laplacian matrices and other matrices associated to a graph of a total graph with its original graph, or, say, at least relating that of the ...