I've been trying to solve the exercise 7(a) of Velleman's "How To Prove It" and haven't succeeded. It asks the verification of the following equivalence:
$$ (P \to Q) \land (Q \to R) = (P \to R) \land ((P \leftrightarrow Q) \lor (R \leftrightarrow Q)) $$
While checking the website for help, I found a question posed by the user "yamad", who, despite his concern with a step futher on the resolution, came to this possible reduced form:
$$(\lnot P \lor Q) \land (\lnot Q \lor R) \land (\lnot P \lor R)$$
The problem is I couldn't even get to this step or any other simplfied form. I would appreciate if someone could provide me a hint.