In philosophical logic, supervaluationism is a semantics for dealing with irreferential singular terms and vagueness.
[1] It allows one to apply the tautologies of propositional logic in cases where truth values are undefined.
According to supervaluationism, a proposition can have a definite truth value even when its components do not.
A supervaluation V is a function from sentences to truth values such that x is supertrue (i.e. V(x)=True) if and only if v(x)=True for every v. Likewise for superfalse.
For example, let Lp be the formal translation of "Pegasus likes licorice".