Definition
Signed Formula
A signed formula is a pair
where is a sign and is a formula. The sign indicates that is true; the sign indicates that is false. Signed formulas are used in the semantic tableau method to track truth-value assignments during the decomposition of complex formulas.
Signs
Signs
— the formula is true — the formula is false A signed formula
asserts that holds under some interpretation. A signed formula asserts that does not hold.