valuation function

Noun

 * 1)  A function which assigns a truth value to every well-formed formula, which is identical to the model's interpretation function when applied to atomic propositions, and which otherwise assigns a truth value recursively depending on the formula's top logical connective and the truth values of the subformulae surrounding that logical connective.
 * Say that a model's interpration assigns true to A and false to B. Then the valuation function assigns false to "not A", true to "not B", false to "A implies B", false to "A and B", and true to "A or B".