HeapSort[l] performs a heap sort on the items of list l.

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.

IndependentSetQ[g, i] yields True if the vertices in list i define an independent set in graph g.

InduceSubgraph[g, s] constructs the subgraph of graph g induced by the list of vertices s.

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

IntervalGraph[l] constructs the interval graph defined by the list of intervals l.

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