Multipartite Moore Digraphs
نویسنده
چکیده
We derive some Moore-like bounds for multipartite digraphs, which extend those of bipartite digraphs, assuming that every vertex of a given partite set is adjacent to the same number of vertices (δ) in each of the other independent sets. We determine when a Moore multipartite digraph is weakly distanceregular. Within this framework, some necessary conditions for the existence of a Moore r-partite digraph with interpartite out-degree δ > 1 and diameter k = 2m are obtained. In the case δ = 1, which corresponds to almost Moore digraphs, a necessary condition in terms of the permutation cycle structure is derived. Also, we present some constructions of dense multipartite digraphs of diameter two that are vertex-transitive. AMS subject classifications. 05C20 05C50 05E30
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