Match the following : List - IList - II (a) (p→q)⇔(¬q→¬p) (i) Contrapositive (b) [(p∧q)→r]⇔[p→(q→r)]…

$(p\to q)\Leftrightarrow(\neg q\to\neg p)$ is the contrapositive law (i); $[(p\wedge q)\to r]\Leftrightarrow[p\to(q\to r)]$ is the exportation law (ii); $(p\to q)\Leftrightarrow[(p\wedge\neg q)\to o]$, where o is a contradiction, is reductio ad absurdum (iii), since assuming p and not-q leads to falsity; and $(p\leftrightarrow q)\Leftrightarrow[(p\to q)\wedge(q\to p)]$ defines equivalence (iv). The code is (i), (ii), (iii), (iv).