A 1989 paper by Jerrum and Sinclair reduces a problem about finding these things to ferromagnetic instances of the Ising model to show that finding the partition function of the latter is #P-complete. A poly-time approximation ratio of 0.878 achieved by the Goemans-Williamson algorithm for a problem about these things is optimal (15[1])only if the unique game conjecture holds. The size of one type of these things is equal to the total number of disjoint paths by Menger’s theorem. The Stoer-Wagner algorithm finds one of these things for (*) undirected graphs recursively, while Karger’s algorithm computes it probabilistically. The “minimum” one of these things can be produced from the Ford-Fulkerson algorithm (-5[1])via (10[1])a namesake theorem that relates it to the maximum flow. For 10 points, name these partitions of a graph (10[1])into two disjoint subsets of vertices. ■END■