| m ≠ 0 ∧ m ≤ # x1, (r ' + x1)[m] = x2 .last, (r ' + x1)[# x2] = x2 .last, path(r ' + x2, H), reachable-n(H, # x2, r, x2 .last), # x2 < m, # x2 < # x1, m ≤ # x1, path(r ' + x1, H) ⊦ x1 = [], x2 = [], path(r ' + firstn(m, x1), H) ∧ x1[m -1] = x2 .last |
(r ' + x1)[m] = x2 .last, (r ' + x1)[# x2] = x2 .last, path(r ' + x2, H), reachable-n(H, # x2, r, x2 .last), # x2 < m, # x2 < # x1, m ≤ # x1, path(r ' + x1, H) ⊦ x1 = [], x2 = [], path(r ' + firstn(m, x1), H) ∧ x1[m - 1] = x2 .last
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ n -1 = n - 1], [CSIMPSEQ : ⊦ m < n → n ≠ 0])]]