背はい理り法ほう

noun

reductio ad absurdum; proof by contradiction

A logical method in mathematics and philosophy where a proposition is proven by showing that its negation leads to a contradiction.

• 背はい理り法ほうを使つかって、√2が無む理り数すうであることを証しょう明めいできる。

  Using proof by contradiction, one can prove that √2 is irrational.