ok   vertices 0, 1, 2 are sources
ok   the three sets are convex
ok   the roots are different and lie in their sets
ok   the vertices in all three sets are exactly 3, 5, 6, 7, 9
ok   U_1 and U_3 omit vertices that are not sources (8; 4 and 8)
ok   column I(v) of the table
ok   dashes of the table are exactly the pairs (v, i) with v not in U_i
ok   the assignment of every row satisfies (A1)-(A3)
ok   (P) holds for the potential of the table
ok   the three arborescences are independent (explicit paths): ok
ok   root paths to 9 are 0,5,9; 1,4,6,9; 2,3,7,9: [[0, 5, 9], [1, 4, 6, 9], [2, 3, 7, 9]]
ok   the six inequalities at v = 9 have the printed values
ok   the instance has exactly 6 families of independent arborescences: 6
ok   on the vertices 0..8 there are exactly 5 families: 5
ok   brute force over all choices of entering arcs on 0..8 also gives 5: 5
ok   of the 5 families on 0..8, exactly 2 cannot be extended to vertex 9 (extendable: 3)
ok   for the potential of the table the listed assignment is the only one of minimum cost at every vertex
ok   at vertex 9 the six admissible assignments cost -3, -1, -1, 0, 1, 2: [-3, -1, -1, 0, 1, 2]
ok   three-set instance: J(v) has three elements with different roots at v = 3
EXAMPLE PASS
