# y + # z = n0 + n, # y = n0, n ≤ # y + # z ⊦ ∃ y0, z0. y + z = y0 + z0 ∧ # z0 = n
Used simplifier rules: n ≤ m ⊦ n0 = m - n ↔ m = n0 + n; (elim) Used terms: # y + # z, n, n0