Found:

Propositional formula

**SEMANTICS: **a well-formed expression of
**propositional logic**. What counts as a propositional formula is defined by the syntax of propositional logic:

(i) a propositional letters in the vocabulary of L are formulas in L b if psi is a formula of L, Neg psi is too c if phi and psi are formulas in L, (phi & psi), (phi V psi), (phi -> psi) and (phi <-> psi) are too d only that which can be generated by the clauses (a)-(c) in a finite number of steps is a formula in L.The clauses (a)-(c) define what counts as a formula; clause (d) states that nothing else can be a formula of L.

LIT. | Gamut, L.T.F. (1991) |