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Converse, Inverse, Contrapositive

Given an if-then statement "if p, then q", we can create three related statements:

A conditional statement consists of two parts, a hypothesis in the “if” clause and a conclusion in the “then” clause.  For instance, “If it rains, then they will cancel school.” 
              “It rains, “is the hypothesis.
              “They will cancel school,” is the conclusion.

To form the converse of the conditional statement, interchange the hypothesis and the conclusion.
            The converse of “If it rains, then they will cancel school” is “If they cancel school, then it rains.”

To form the inverse of the conditional statement, take the negation of both the hypothesis and the conclusion.
            The inverse of “If it rains, then they will cancel school” is “If it does not rain, then they do not cancel school.”

To form the contrapositive of the conditional statement, interchange the hypothesis and the conclusion of the inverse statement. 
            The contrapositive of “If it rains, then they will cancel school” is “If they do not cancel school, then it does not rain.”

Statement	If p, then q.
Converse	If q, then p.
Inverse	If not p, then not q.
Contrapositive	If not q, then not p.

 

If the statement is true, then the contrapositive is also logically true. If the converse is true, then the inverse is also logically true.