"Let V be a nonempty set and E contained in VxV such that u is not equal to v for all (u,v) in E. The pair G=(V,E) is called a graph. The members of the set V are called the nodes or vertices of G and the members of E are called the edges of G. If (u,v) is in E, u and v are said to be adjacent, the edge (u,v) is usually denoted simply uv. If each e
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