| ⊦ sort(x + ins≤(a, y)) = ins≤(a, sort(x + y)) |
perm(x, y), ordered≤(x), ordered≤(y) ⊦ x = y
⊦ perm(sort(x + ins≤(a, y)), ins≤(a, sort(x + y))) ∧ ordered≤(sort(x + ins≤(a, y))) ∧ ordered≤(ins≤(a, sort(x + y))), sort(x + ins≤(a, y)) = ins≤(a, sort(x + y))
Used terms: sort(x + ins≤(a, y)), ins≤(a, sort(x + y))