| ∀ a. ¬ a ∈ s ∨ ¬ a ∈ s0, ∀ a. ¬ a ∈ s ∨ ¬ a ∈ s1 ⊦ ∀ a. ¬ a ∈ s ∨ ¬ a ∈ s0 ∪ s1 |
a ∈ s, ∀ a. ¬ a ∈ s ∨ ¬ a ∈ s0, ∀ a. ¬ a ∈ s ∨ ¬ a ∈ s1, a ∈ s0 ∨ a ∈ s1 ⊦ # s = 0, s = ∅
Used simplifier rules: unrax: ⊦ a ∈ s ∪ s0 ↔ a ∈ s ∨ a ∈ s0;%una: ⊦ (s ∪ s0) ∪ s1 = s ∪ s0 ∪ s1;%unc: ⊦ s ∪ s0 = s0 ∪ s;%size-zero-01: ⊦ s ≠ ∅ → # s ≠ 0; (forward) from specification set-basic%ne-01: ⊦ a ∈ s → s ≠ ∅; (forward) from specification set-basic