1). ~(K•L) 2). K -> L Therefore, ~K | 3). ~~K Assumption for Indirect Proof | 4). K, 3, Double Negation | 5). L, 2, Modus Ponens | 6). ~K v ~L 1, DeMorgan's Law | 7). ~L v ~K 6, Commutation | 8). ~~L 5, Double Negation | 9). ~K 7,8, Disjunctive syllogism |10). K•~K 4,9, Conjunction 11). ~K Lines 4-10 Indirect Proof Edwin
Number | Statement | Line(s) Used | Reason |
1 | ~(K & L) | ||
2 | K --> L | ||
:. | ~K | ||
3 | ~K v ~L | 1 | De Morgan’s Law |
4 | K --> ~L | 3 | Material Implication |
5 | L --> ~K | 4 | Transposition |
6 | K --> ~K | 2,5 | Hypothetical Syllogism |
7 | ~K v ~K | 6 | Material Implication |
8 | ~K | 7 | Tautology |