e/Proof by contradiction

Information
has gloss	eng: In logic, proof by contradiction is a form of proof that establishes the truth or validity of a proposition by showing that the proposition being false would imply a contradiction. Since by the law of bivalence a proposition must be either true or false, and its falsity has been shown impossible, the proposition must be true.
lexicalization	eng: proof by contradiction
instance of	(noun) a formal series of statements showing that if one thing is true something else necessarily follows from it proof