Fuzzy logic is used in artificial intelligence.

In fuzzy logic, a proposition has a truth value that is a number between 0 and 1, inclusive.

A proposition with a truth value of 0 is false and one with a truth value of 1 is true.

Truth values that are between 0 and 1 indicate varying degrees of truth.

For instance, the truth value 0.8 can be assigned to the statement “Fred is happy,”because Fred is happy most of the time,

and the truth value 0.4 can be assigned to the statement “John is happy,” because John is happy slightly less than half the time.