TransitiveReduction[g] finds a smallest graph that has the same transitive closure as g.
TransposeTableau[t] reflects a Young tableau t along the main diagonal, creating a different tableau.
TravelingSalesmanBounds[g] gives upper and lower bounds on a minimum-cost traveling salesman tour of graph g.
TravelingSalesman[g] finds an optimal traveling salesman tour in graph g.
TreeIsomorphismQ[t_1, t_2] yields True if the trees t_1 and t_2 are isomorphic. It yields False otherwise.
TreeQ
(Combinatorica Package Symbol) TreeQ[g] yields True if graph g is a tree.
TriangleInequalityQ[g] yields True if the weights assigned to the edges of graph g satisfy the triangle inequality.
TutteGraph returns the Tutte graph, the first known example of a 3-connected, 3-regular, planar graph that is non-Hamiltonian.
UnionSet[a, b, s] merges the sets containing a and b in union-find data structure s.
Uniquely3ColorableGraph returns a 12-vertex, triangle-free graph with chromatic number 3 that is uniquely 3-colorable.