fix incorrect theorem
Proloy Mishra
1 year, 9 months ago
170 | 170 | theorem |
171 | 171 | not(not(A)) = A |
172 | 172 | proof |
173 | 1 = 1 | |
174 | 1 = or(A, not(A)) | |
175 | 1 = or(not(A), A) | |
176 | or(not(not(A)), 1) = or(not(not(A)), or(not(A), A)) [by congruence of X and or(not(not(A)), X)] | |
177 | not(not(A)) = or(not(not(A)), or(not(A), A)) | |
178 | not(not(A)) = or(or(not(not(A)), not(A)), A) | |
179 | not(not(A)) = or(or(not(A), not(not(A))), A) | |
180 | not(not(A)) = or(1, A) | |
181 | not(not(A)) = or(A, 1) | |
173 | and(or(not(not(A)), A), 1) = and(or(not(not(A)), A), 1) | |
174 | and(or(not(not(A)), A), 1) = and(or(A, not(not(A))), 1) | |
175 | and(or(not(not(A)), A), 1) = and(or(A, not(not(A))), or(A, not(A))) | |
176 | and(or(not(not(A)), A), 1) = or(A, and(not(not(A)), not(A))) | |
177 | and(or(not(not(A)), A), 1) = or(A, and(not(A), not(not(A)))) | |
178 | and(or(not(not(A)), A), 1) = or(A, 0) | |
179 | and(or(not(not(A)), A), 1) = A | |
180 | and(or(not(not(A)), A), or(not(A), not(not(A)))) = A [by #or-comp with A=not(A)] | |
181 | and(or(not(not(A)), A), or(not(not(A)), not(A))) = A | |
182 | or(not(not(A)), and(A, not(A))) = A | |
183 | or(not(not(A)), 0) = A | |
182 | 184 | not(not(A)) = A |
183 | 185 | qed |