191 research outputs found
Upper bound theorem for odd-dimensional flag triangulations of manifolds
We prove that among all flag triangulations of manifolds of odd dimension
2r-1 with sufficiently many vertices the unique maximizer of the entries of the
f-, h-, g- and gamma-vector is the balanced join of r cycles. Our proof uses
methods from extremal graph theory.Comment: Clarifications and new references, title has change
Even Orientations and Pfaffian graphs
We give a characterization of Pfaffian graphs in terms of even orientations,
extending the characterization of near bipartite non--pfaffian graphs by
Fischer and Little \cite{FL}. Our graph theoretical characterization is
equivalent to the one proved by Little in \cite{L73} (cf. \cite{LR}) using
linear algebra arguments
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