| Pelem(a, c), Pelem(c, c0), Pelem(c1, b), rtc(m0, Pelem)(c0, b), rtc(m0, Pelem)(c, c1), ∀ Pelem, a, c, b. Pelem(a, c) ∧ rtc(m0, Pelem)(c, b) → (∃ c. rtc(m0, Pelem)(a, c) ∧ Pelem(c, b)) ⊦ ∃ c1. (∃ c. Pelem(a, c) ∧ rtc(m0, Pelem)(c, c1)) ∧ Pelem(c1, b), ∃ c. Pelem(a, c) ∧ rtc(m0, Pelem)(c, c1) |
Used terms: c