# Necessary and Sufficient Condition Set

(Redirected from necessary and sufficient conditions)

A Necessary and Sufficient Condition Set is a condition set composed of Necessary Conditions and Sufficient Conditions.

**See:**Logic, Statement (Logic), if And Only if.

## References

### 2015

- (Wikipedia, 2015) ⇒ http://en.wikipedia.org/wiki/Necessity_and_sufficiency Retrieved:2015-1-20.
- In logic,
**necessity**and sufficiency are implicational relationships between statements. The assertion that one statement is a*necessary and sufficient*condition of another means that the former statement is true if and only if the latter is true. That is, the two statements must be either simultaneously true or simultaneously false.^{[1]}^{[2]}^{[3]}In ordinary English, 'necessary' and 'sufficient' indicate relations between conditions or states of affairs, not statements. Being a male sibling is a necessary and sufficient condition for being a brother. Fred's being a male sibling is necessary and sufficient for the truth of the statement that Fred is a brother.

- In logic,