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.
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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)
“In the most desirable conditions, the child learns to manage anxiety by being exposed to just the right amounts of it, not much more and not much less. This optimal amount of anxiety varies with the child’s age and temperament. It may also vary with cultural values.... There is no mathematical formula for calculating exact amounts of optimal anxiety. This is why child rearing is an art and not a science.”
—Alicia F. Lieberman (20th century)