IdenticalQ[g, h] yields True if graphs g and h have identical edge lists, even though the associated graphics information need not be the same.

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

InDegree[g, n] returns the in-degree of vertex n in directed graph g. InDegree[g] returns the sequence of in-degrees of the vertices in directed graph g.

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

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

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.

Invariants is an option to the functions Isomorphism and IsomorphicQ that informs these functions about which vertex invariants to use in computing equivalences between ...

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