NOToperaattori

NOToperaattori, or logical NOT operator, is a unary operator used in logic and computing to negate a boolean value. It inverts its operand: if the input is true, the result is false, and if the input is false, the result is true. In Boolean algebra and propositional logic, this operation is fundamental for expressing negation and complements.

Notation and equivalents vary by context. In many programming languages the negation is written with the exclamation mark (!), as in C, C++, Java, and JavaScript, or with the tilde (~) for bitwise negation. In mathematics and some programming contexts the symbol ¬ or the word NOT is used. SQL uses NOT as a keyword to negate boolean expressions, and hardware logic uses the NOT gate (inverter).

Applications and properties. The NOT operator is used to form negated conditions in control flow, to implement logical expressions, and to perform bitwise operations on binary data. In search and filtering, NOT excludes terms or records. A key property in Boolean logic is De Morgan's laws, which show how NOT distributes over AND and OR: not (A and B) equals (not A) or (not B), and not (A or B) equals (not A) and (not B).

Context and scope. Negation is a foundational operation in classical logic and digital design, as well as in many programming languages with language-specific syntax and three-valued logic considerations (as in SQL, where NULL can affect the outcome of NOT).