A finite group attached to the laplacian of a graph
Discrete Mathematics
A combinatorial Laplacian with vertex weights
Journal of Combinatorial Theory Series A
Chip-Firing and the Critical Group of a Graph
Journal of Algebraic Combinatorics: An International Journal
Line Digraph Iterations and Connectivity Analysis of de Bruijn and Kautz Graphs
IEEE Transactions on Computers
Heredity of the index of convergence of the line digraph
Discrete Applied Mathematics
Line Digraph Iterations and the (d, k) Digraph Problem
IEEE Transactions on Computers
A bijective proof of a theorem of knuth
Combinatorics, Probability and Computing
Algebraic and combinatorial aspects of sandpile monoids on directed graphs
Journal of Combinatorial Theory Series A
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We generalize a theorem of Knuth relating the oriented spanning trees of a directed graph G and its directed line graph LG. The sandpile group is an abelian group associated to a directed graph, whose order is the number of oriented spanning trees rooted at a fixed vertex. In the case when G is regular of degree k, we show that the sandpile group of G is isomorphic to the quotient of the sandpile group of LG by its k-torsion subgroup. As a corollary we compute the sandpile groups of two families of graphs widely studied in computer science, the de Bruijn graphs and Kautz graphs.