Inversions[p] counts the number of inversions in permutation p.

IsomorphismQ[g, h, p] tests if permutation p defines an isomorphism between graphs g and h.

Josephus[n, m] generates the inverse of the permutation defined by executing every m\[Null]^th member in a circle of n members.

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 ...

LabeledTreeToCode[g] reduces the tree g to its Prüfer code.

LeviGraph returns the unique (8, 3)-cage, a 3-regular graph whose girth is 8.

LexicographicPermutations[l] constructs all permutations of list l in lexicographic order.

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

LineGraph[g] constructs the line graph of graph g.

LNorm[p] is a value that the option WeightingFunction, used in the function SetEdgeWeights, can take. Here p can be any integer or Infinity.