ToCycles[p] gives the cycle structure of permutation p as a list of cyclic permutations.
TopologicalSort[g] gives a permutation of the vertices of the directed acyclic graph g such that an edge (i, j) implies that vertex i appears before vertex j.
TreeToCertificate[t] returns a binary string that is a certificate for the tree t such that trees have the same certificate if and only if they are isomorphic.
Turan
(Combinatorica Package Symbol) Turan[n, p] constructs the Turán graph, the extremal graph on n vertices that does not contain CompleteGraph[p].
UnrankSetPartition[r, s, k] finds a k-block set partition of s with rank r. UnrankSetPartition[r, n, k] finds a k-block set partition of {1, 2, ..., n} with rank r.
UnrankPermutation[r, l] gives the r\[Null]^th permutation in the lexicographic list of permutations of list l. UnrankPermutation[r, n] gives the r\[Null]^th permutation in ...
UnrankSetPartition[r, set] finds a set partition of set with rank r. UnrankSetPartition[r, n] finds a set partition of {1, 2, ..., n} with rank r.
VertexConnectivity[g] gives the minimum number of vertices whose deletion from graph g disconnects it. VertexConnectivity[g, Cut] gives a set of vertices of minimum size ...
Vertices[g] gives the coordinates of each vertex of graph g embedded in a plane.Vertices[g, All] gives the embedding of the graph along with graphics options associated with ...
Wheel
(Combinatorica Package Symbol) Wheel[n] constructs a wheel on n vertices, which is the join of CompleteGraph[1] and Cycle[n - 1].