Answer to Question #265789 in Discrete Mathematics for hasnain

Question

Show that (p → q) → (r → s) and (p → r) →

(q → s) are not logically equivalent.

The dual of a compound proposition that contains only the

logical operators ∨, ∧, and ¬ is the compound proposition

obtained by replacing each ∨ by ∧, each ∧ by ∨, each T

by F, and each F by T. The dual of s is denoted by s

∗.