| frag*(IOAut(start, step, ext))(sl, al) ⊦ ∃ sl0, al0. sl0.head = sl.head ∧ sl0.last = sl.last ∧ frag*(IOAut(start, step, ext))(sl0, al0) ∧ (∀ sl1, al1. sl1.head = sl.head ∧ sl1.last = sl.last ∧ frag*(IOAut(start, step, ext))(sl1, al1) → # sl0 ≤ # sl1) |