HamiltonianPath[g] finds a Hamiltonian path in graph g if one exists. HamiltonianPath[g, All] gives all Hamiltonian paths of graph g.

HasseDiagram[g] constructs a Hasse diagram of the relation defined by directed acyclic graph g.

Heapify[p] builds a heap from permutation p.

HeawoodGraph returns a smallest (6, 3)-cage, a 3-regular graph with girth 6.

HerschelGraph returns a graph object that represents a Herschel graph.

Hypercube[n] constructs an n-dimensional hypercube.

IdentityPermutation[n] gives the size-n identity permutation.

InitializeUnionFind[n] initializes a union-find data structure for n elements.

InversePermutation[p] yields the multiplicative inverse of permutation p.

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