In the previous post, we have discussed compound propositions. We learned that compound proposition is a proposition formed from simple propositions using some logical connectors. The first logical connector that we are going learn is about “not” which is used for negation.

The negation of a proposition p denoted by ~p (read as “not p”) and is defined by the following truth table. As we can see, if p is true, then ~p is false. If p is false, then ~p is true.

Consider the following negations.

Example 1
q: I am going to the party.
~q: I am not going to the party.

Example 2
r: John is wealthy.
~r: John is not wealthy.  Continue reading →