Validity - Natural & Formal Sciences - Mathematics & Logic Dictionary Definition Property of a sentence (formula closed under free variables) that it is true under every admissible interpretation or valuation in the logic; a sentence that holds in all models is valid (a logical truth).
Validity - Natural & Formal Sciences - Mathematics & Logic Dictionary Definition Property of a sentence (formula closed under free variables) that it is true under every admissible interpretation or valuation in the logic; a sentence that holds in all models is valid (a logical truth).