| s ⊆ s1 ++ a, a ∈ s, ∀ s. s ⊆ s1 → (∃ s2. s ∪ s2 = s1 ∧ s ∩ s2 = ∅) ⊦ s = ∅, # s = 0, a ∈ s1, ∃ s2. s ∪ s2 = s1 ++ a ∧ s ∩ s2 = ∅ |
s ⊆ s1 ++ a, a ∈ s, s -- a ⊆ s1 → (∃ s2. (s -- a) ∪ s2 = s1 ∧ (s -- a) ∩ s2 = ∅) ⊦ s = ∅, # s = 0, a ∈ s1, ∃ s2. s ∪ s2 = s1 ++ a ∧ s ∩ s2 = ∅
Used terms: s -- a