Literal

Definition

Literal

A literal is an atom or the negation of an atom. The precise reading depends on the order of the underlying logic: propositional literals and first-order literals differ in what counts as an atom.

Propositional logic

Definition

Literal (Propositional Logic)

A literal is an atom or the negation of an atom.

• A positive literal is an atom $p$ (positive literal).
• A negative literal is the negation $\neg p$ of an atom (negative literal).

Every clause and every conjunctive normal form is built from literals.

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