| ∀ a. ((t = leaf ⊃ a; t .leftmost)) = a ∨ ((t = leaf ⊃ a; t .leftmost)) ∈ t, ∀ a. ((t1 = leaf ⊃ a; t1 .leftmost)) = a ∨ ((t1 = leaf ⊃ a; t1 .leftmost)) ∈ t1 ⊦ ((t = leaf ⊃ a0; t .leftmost)) = a, ((t = leaf ⊃ a0; t .leftmost)) = a0, ((t = leaf ⊃ a0; t .leftmost)) ∈ t1, ((t = leaf ⊃ a0; t .leftmost)) ∈ t |
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (a0)]]