Hintikka set
In mathematical logic, a Hintikka set is a set of logical formulas whose elements satisfy the following properties: An atom or its conjugate can appear in the set but not both, If a formula in the set has a main operator that is of "conjunctive-type", then its two operands appear in the set, If a formula in the set has a main operator that is of "disjunctive-type", then at least one of its two operands appears in the set. The exact meaning of "conjunctive-type" and "disjunctive-type" is defined by the method of semantic tableaux.