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Propositional letters

SEMANTICS: the basic expressions of a propositional language (also called propositional variables, as opposed to logical constants like Neg and &). Conventionally, a letter from the range {p, q, r or a p with primes (p',p'',...) represents a single proposition. The propositional formulas of propositional logic are built from propositional letters and connectives. Propositional letters should be distinguished from metavariables such as phi and psi which are used in the definitions of the logic. See also propositional logic.

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