| # A = # A0, i + 1 < # A0, perm(A[0, y][1, x], A0), sorted(A, 2, i + 2), i ≤ # A0, 0 ≠ i → x < A[2] ⊦ x < y, sorted(A[1, x], 1, i + 2) ∧ perm(A[1, x][0, y], A0) |
# A = # A0, i + 1 < # A0, perm(A[0, y][1, x], A0), sorted(A, 2, i + 2), i ≤ # A0, 0 ≠ i → x < A[2] ⊦ x < y, sorted(A[1, x], 1, i + 2)
# A = # A0, i + 1 < # A0, perm(A[0, y][1, x], A0), sorted(A, 2, i + 2), i ≤ # A0, 0 ≠ i → x < A[2] ⊦ x < y, perm(A[1, x][0, y], A0)