 In Kleene’s strong three-valued logic, the value \(\bot\) (undefined) can be interpreted as “not yet defined”. So one could think of formulae with the value \(\bot\) as formulae that actually have a classical truth value (true or false), but which has just not been determined yet. This interpretation of undefined is reflected in the truth tables for the logic, given below. The upper truth table is for disjunction, the lower for negation: