| # s0 + # s = #(s0 ∪ s) + #(s0 ∩ s), #(s0 ∩ s) ≤ # s0 + # s ⊦ #(s ∪ s0) = # s0 + # s - #(s0 ∩ s), a ∈ s, a ∈ s0 |
Used simplifier rules: unc: ⊦ s ∪ s0 = s0 ∪ s;%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%c: ⊦ m + n = n + m; from specification nat-basic2%eqs: ⊦ m = n + n0 ∧ m = n + n1 → n0 = n1; (forward) from specification nat-basic2%n ≤ m ⊦ n0 = m - n ↔ m = n0 + n; (elim) Used terms: # s0 + # s, #(s0 ∩ s), n