منابع مشابه
A Cancellation Property for the Direct Product of Graphs
Given graphs A, B and C for which A × C ∼= B × C, it is not generally true that A ∼= B. However, it is known that A × C ∼= B × C implies A ∼= B provided that C is non-bipartite, or that there are homomorphisms from A and B to C. This note proves an additional cancellation property. We show that if B and C are bipartite, then A×C ∼= B × C implies A ∼= B if and only if no component of B admits an...
متن کاملCancellation of digraphs over the direct product
In 1971 Lovász proved the following cancellation law concerning the direct product of digraphs. If A, B and C are digraphs, and C admits no homomorphism into a disjoint union of directed cycles, then A × C ∼= B × C implies A ∼= B. On the other hand, if such a homomorphism exists, then there are pairs A ≁= B for which A×C ∼= B×C . This gives exact conditions on C that governwhether cancellation ...
متن کاملA Note on Tensor Product of Graphs
Let $G$ and $H$ be graphs. The tensor product $Gotimes H$ of $G$ and $H$ has vertex set $V(Gotimes H)=V(G)times V(H)$ and edge set $E(Gotimes H)={(a,b)(c,d)| acin E(G):: and:: bdin E(H)}$. In this paper, some results on this product are obtained by which it is possible to compute the Wiener and Hyper Wiener indices of $K_n otimes G$.
متن کاملIndependence in Direct-Product Graphs
Let α(G) denote the independence number of a graph G and let G ×H be the direct product of graphs G and H. Set α(G ×H) = max{α(G) · |H|, α(H) · |G|}. If G is a path or a cycle and H is a path or a cycle then α(G×H) = α(G×H). Moreover, this equality holds also in the case when G is a bipartite graph with a perfect matching and H is a traceable graph. However, for any graph G with at least one ed...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2009
ISSN: 0012-365X
DOI: 10.1016/j.disc.2008.06.004