Solutions to Homework #9, Problems 23-29

3. A ( (B is a logical consequence of A ( B ( C, B ( (A ( (C), and A ( C. Since what we want to show is a biconditional, we need to prove A ( (B and (B ( A. Let’s assume A. Now, since A ( C, one of our premises becomes B ( (A ( (A). However A ( (A is a contradiction and therefore always false. Since the consequent is always false, so is the ... ................
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