| ∀ b. b ∈ S → reach(a, b, n) ∧ ¬ reach<(a, b, n) ⊦ reachS(a, S -- b, n) |
⊦ reachS(a, S, n) ↔ (∀ b. b ∈ S → reach(a, b, n) ∧ ¬ reach<(a, b, n))
∀ b. b ∈ S → reach(a, b, n) ∧ ¬ reach<(a, b, n) ⊦ ∀ b0. b0 ∈ S -- b → reach(a, b0, n) ∧ ¬ reach<(a, b0, n)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (n, S -- b, a)]]