| ⊦ Inv-end(A, A0, i, j, y) → ( Inv-end(A1, A2, i0, j0, y0) ↔ # A ≠ 0 ∧ # A = # A0 ∧ j ≤ i ∧ (j ≠ i → y ≤ A[j + 1]) ∧ sorted(A, 0, (j = i ⊃ i;i + 1)) ∧ perm(A[j, y], A0) → # A1 ≠ 0 ∧ # A1 = # A2 ∧ j0 ≤ i0 ∧ (j0 ≠ i0 → y0 ≤ A1[j0 + 1]) ∧ sorted(A1, 0, (j0 = i0 ⊃ i0;i0 + 1)) ∧ perm(A1[j0, y0], A2)) |
Inv-end(A, A0, i, j, y) ⊦ Inv-end(A1, A2, i0, j0, y0) ↔ # A ≠ 0 ∧ # A = # A0 ∧ j ≤ i ∧ (j ≠ i → y ≤ A[j + 1]) ∧ sorted(A, 0, (j = i ⊃ i;i + 1)) ∧ perm(A[j, y], A0) → # A1 ≠ 0 ∧ # A1 = # A2 ∧ j0 ≤ i0 ∧ (j0 ≠ i0 → y0 ≤ A1[j0 + 1]) ∧ sorted(A1, 0, (j0 = i0 ⊃ i0;i0 + 1)) ∧ perm(A1[j0, y0], A2)