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Given a graph G = (V, E) and a (not necessarily proper) edge-coloring of G, we consider the complexity of finding a spanning tree of G with as many different colors as possible, and of finding one with as few different colors as possible. We show that the first problem is equivalent to finding a common independent set of maximum cardi-nality in two(More)
A weighted graph is a graph in which each edge e is assigned a non-negative number w(e), called the weight of e. The weight of a cycle is the sum of the weights of its edges. The weighted degree d w (v) of a vertex v is the sum of the weights of the edges incident with v. In this paper, we prove the following result: Suppose G is a 2-connected weighted(More)
Given a graph G and a subgraph H of G, let rb(G, H) be the minimum number r for which any edge-coloring of G with r colors has a rainbow subgraph H. The number rb(G, H) is called the rainbow number of H with respect to G. Denote mK 2 a matching of size m and B n,k a k-regular bipartite graph with bipartition (X, Y) such that |X| = |Y | = n and k ≤ n. In(More)