Definition:Logical Connective/Unary

Definition

A unary logical connective (or one-place connective) is a logical connective whose effect on its compound statement is determined by the truth value of one substatement.

In standard Aristotelian logic, there are four of these.

The only non-trivial one is logical not, as shown on Unary Truth Functions.

Also defined as

Some treatments do not consider a unary connective to be a logical connective as such, because it does not actually "connect" anything, but this is a trivial point which can serve only to confuse.

Also see

• Definition:Binary Logical Connective

Linguistic Note

The word unary is pronounced yoo-nary.

Hence when the indefinite article precedes it, the form is (for example) a unary operation.

Sources

• 1980: D.J. O'Connor and Betty Powell: Elementary Logic ... (previous) ... (next): $\S \text{I}: 2$: Logical Constants $(1)$