The operation of interchanging true and false in a logical statement. The negation of 
is often called "NOT-
," and can be denoted 
, or with the negation sign 
, so not-
is written 
.
Note that in computer languages such as C, perl, and the Wolfram Language, not-
is denoted 
.
In FORTRAN, not-
is written .not.A, where 
is a variable of logical type.
