Validity - Valid Formula

Valid Formula

A formula of a formal language is a valid formula if and only if it is true under every possible interpretation of the language. In propositional logic, they are tautologies.

Read more about this topic:  Validity

Famous quotes containing the words valid and/or formula:

    Just as soon as we notice that someone has to force himself to pay attention when dealing and talking with us, we have a valid demonstration that he does not love us or that he does not love us anymore.
    Friedrich Nietzsche (1844–1900)

    But suppose, asks the student of the professor, we follow all your structural rules for writing, what about that “something else” that brings the book alive? What is the formula for that? The formula for that is not included in the curriculum.
    Fannie Hurst (1889–1968)