| # y ≤ # y0, # y = # y0, a0 ' + y0 + z = y + z0, a0 ∈ y ∨ a0 ∈ z0 ⊦ y + z0[# y0 - # y, a] = y + a ' + z |
a0 ' + y0 + z = y + z0, # y = # y0, a0 ∈ y ∨ a0 ∈ z0 ⊦ z0[0, a] = a ' + z
Used simplifier rules: ler: ⊦ m ≤ m; from specification nat%zero: ⊦ m - m = 0; from specification nat%a: ⊦ (x + y) + z = x + y + z; from specification list%app-01: ⊦ x + y = x + z ↔ y = z; from specification list