| path(a ' + y), b ∈ succ(y .last), reach(a, y .last, # y) ⊦ y = [], succ(y .last) = ∅, # succ(y .last) = 0, path(a ' + y + b ') |
⊦ path(x + a ' + b ') ↔ b ∈ succ(a) ∧ path(x + a ')
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ (x + y) + z = x + y + z], [CSIMPSEQ : ⊦ a + x = a ' + x], [CSIMPSEQ : x ≠ [] ⊦ x .butlast + x .last ' = x])], [EXTRATERMS : (a + y .butlast, y .last, b)]]