Even Pairs in Bull-reducible Graphs
A bull is a graph with five vertices a, b, c, d, e and five edges ab, bc, cd, be, ce. A graph G is bull-reducible if no vertex of G lies in two bulls. An even pair is a pair of vertices such that every chordless path joining them has even length. We prove that for every bull-reducible Berge graph G with at least two vertices, either G or its complementary graph \( \bar G \) has an even pair.
KeywordsInduction Hypothesis Bipartite Graph Pairwise Disjoint Adjacent Vertex Perfect Graph
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