The correct answer is: A. Positive literal
A positive literal is a propositional variable or its negation. It is a literal that is true if the propositional variable is true.
A negative literal is a propositional variable or its negation. It is a literal that is true if the propositional variable is false.
Generalized modus ponens is a rule of inference that states that if $P$ implies $Q$ and $P$ is true, then $Q$ must also be true.
A neutral literal is a propositional variable or its negation. It is a literal that is neither true nor false.
Definite clauses are a type of logical formula that is used in logic programming. They are made up of a head and a body. The head is a propositional variable, and the body is a conjunction of literals.
Positive literals are more suitable normal form to be used with definite clauses
6.3-42 24.9-48.3 48.6-11.4 42.9-11.4 132.3-11.4 132.3s0 89.4 11.4 132.3c6.3 23.7 24.8 41.5 48.3 47.8C117.2 448 288 448 288 448s170.8 0 213.4-11.5c23.5-6.3 42-24.2 48.3-47.8 11.4-42.9 11.4-132.3 11.4-132.3s0-89.4-11.4-132.3zm-317.5 213.5V175.2l142.7 81.2-142.7 81.2z"/> Subscribe on YouTube