Shellable graphs and sequentially Cohen-Macaulay bipartite graphs

نویسندگان

  • Adam Van Tuyl
  • Rafael H. Villarreal
چکیده

Associated to a simple undirected graph G is a simplicial complex ∆G whose faces correspond to the independent sets of G. We call a graph G shellable if ∆G is a shellable simplicial complex in the non-pure sense of Björner-Wachs. We are then interested in determining what families of graphs have the property that G is shellable. We show that all chordal graphs are shellable. Furthermore, we classify all the shellable bipartite graphs; they are precisely the sequentially Cohen-Macaulay bipartite graphs. We also give an inductive procedure to build all such shellable bipartite graphs. Because shellable implies that the associated Stanley-Reisner ring is sequentially Cohen-Macaulay, our results complement and extend recent work on the problem of determining when the edge ideal of a graph is (sequentially) Cohen-Macaulay. We also give a new proof for a result of Faridi on the sequentially Cohen-Macaulayness of simplicial forests.

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عنوان ژورنال:
  • J. Comb. Theory, Ser. A

دوره 115  شماره 

صفحات  -

تاریخ انتشار 2008