| ¬(pos('a', sortedchars) ≤ pos('a', sortedchars) ∧ pos('a', sortedchars) ≤ pos('z', sortedchars)) ⊦ upcase('a') = 'A' |
pos('z', sortedchars) < pos('a', sortedchars) ⊦ upcase('a') = 'A'
Used simplifier rules: ⊦ m < n → n ≠ 0;% ⊦ m < n → n ≠ 0; (forward)% ⊦ ¬ m ≤ n ↔ n < m;% ⊦ m ≤ m;