CST329 - Week 4

This week we learned about the concept of proof by contradiction. This includes writing a subproof in which the last two lines are a contradiction. Then, the Reductio ad absurdum (RAA) rule can be applied to derive the negation of the first line of the proof. A contradictory sentence is a sentence that can never be true and is the opposite of a tautology. Next, we spent a chunk of time learning about different proof strategies. The professor gave a lecture on how to best approach writing a proof based on what conclusion you are trying to prove. Some ideas include working backward and working forwards. Next, we learned two new rules: bicondition and equivalence. Lastly, we delved deeper into the three kinds of sentences: tautology, contradictory sentence, and contingent sentence. This week culminated our comprehensive study about the rules and application of propositional logic.