| ⊦ perm(x + (a + y), x0 + (a + y0)) ↔ perm(x + y, x0 + y0) |
Used simplifier rules: perm-rmv-in-list: ⊦ perm(x + a ' + y, x0 + a ' + y0) ↔ perm(x + y, x0 + y0);%a: ⊦ (x + y) + z = x + y + z; from specification list%c: ⊦ a + x = a ' + x; from specification list