In combinatorics, a chain (more commonly called a path) in a graph is a sequence {x1, x2, x3, ... xk} of nodes such that {[x1, x2], [x2, x3], ... [xk-1, xk]} are edges of the graph. In a non-simple graph (one with repeated edges) it is necessary to impose the condition that no edge occur in the sequence more than it's repetition number. In a simple graph, each edge can appear at most once.

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