Question

In this problem you are provided with three biconditionals, and must deduce a new one based on the endpoints of what can be regarded as the chain of the trio. One might, upon saving the maneuver in one‘s mind or one‘s library, dub the generalization of what a successful proof shows as biconditional intro by chaining (although you will no doubt be able to devise a less verbose label for the tactic in question). Expressed metalogically, your overall task is to validate: { P ↔ Q , Q ↔ R , R ↔ S } ⊢ P ↔ S . You are of course free to use the PC oracle during the construction of your proof, but no use of the oracle can remain in your finished, for-credit proof.

Answer 1