Index[p] gives the index of permutation p, the sum of all subscripts j such that p[[j]] is greater than p[[j + 1]].

KnightsTourGraph[m, n] returns a graph with mn vertices in which each vertex represents a square in an m*n chessboard and each edge corresponds to a legal move by a knight ...

LexicographicSubsets[l] gives all subsets of set l in lexicographic order. LexicographicSubsets[n] returns all subsets of {1, 2, ..., n} in lexicographic order.

LoopPosition is an option to ShowGraph whose values tell ShowGraph where to position a loop around a vertex. This option can take on values UpperLeft, UpperRight, LowerLeft, ...

MakeUndirected[g] gives the underlying undirected graph of the given directed graph g.

MaximumClique[g] finds a largest clique in graph g. MaximumClique[g, k] returns a k-clique, if such a thing exists in g; otherwise it returns {}.

MeredithGraph returns a 4-regular, 4-connected graph that is not Hamiltonian, providing a counterexample to a conjecture by C. St. J. A. Nash\[Dash]Williams.

MinimumSpanningTree[g] uses Kruskal's algorithm to find a minimum spanning tree of graph g.

MinimumVertexCover[g] finds a minimum vertex cover of graph g.

M[g] gives the number of edges in the graph g. M[g, Directed] is obsolete because M[g] works for directed as well as undirected graphs.