What methods for making a proof always involves the negation of a statement?

One common method that involves the negation of a statement is proof by contradiction. In this approach, to prove a statement ( P ), one assumes that ( P ) is false (i.e., ( \neg P )) and then shows that this assumption leads to a logical contradiction. Another method is proof by contraposition, where instead of proving ( P ) implies ( Q ), one proves its equivalent form, ( \neg Q ) implies ( \neg P ). Both methods hinge on examining the negation to establish the truth of the original statement.