noun
necessary and sufficient condition
Technical term used in logic, mathematics, and philosophy. Refers to a condition that is both required and enough for a statement to be true.
三角形が正三角形であることは、三辺が等しいことの必要十分条件です。
Being an equilateral triangle is a necessary and sufficient condition for having three equal sides.
この定理の必要十分条件を証明しなさい。
Prove the necessary and sufficient condition for this theorem.