Paths, Adjacency, Cycles
Two vertices vi and vj are adjacent if there exists an edge e ? E such that e = (vi, vj).
A path p is a sequence of vertices of V of the form p = v1 v2 ... vn (n >= 2) in which each vertex vi is adjacent to vi+1 (for 1<= i <= n-1).
A cycle is a path p = v1 v2 ... vn such that v1 = vn