| reach<(source, a, n0), b ∈ succ(a) ⊦ succ(a) = ∅, # succ(a) = 0, ∃ m. ¬ n0 < m ∧ reach(source, b, m) |
⊦ reach<(a, b, n) ↔ (∃ m. m < n ∧ reach(a, b, m))
∃ m. m < n0 ∧ reach(source, a, m), b ∈ succ(a) ⊦ succ(a) = ∅, # succ(a) = 0, ∃ m. ¬ n0 < m ∧ reach(source, b, m)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (n0, a, source)]]