SKEDSOFT

Logical Identities: If two propositional forms are logically equivalent one can be substituted for the other in any proposition in which they occur. Table below shows a list of important equivalences, which are called “identities.” The symbols P, Q , and R represent arbitrary propositional forms. The symbol “1” is used to represent either a “tautology” or a true proposition. Similarly, “0” represents a false proposition or a contradiction.

All the above identities can be proved by constructing truth tables. The following table gives a list of tautologies which are implications.