1. A type of semantics for deductive systems differing from semantics employing logical matrices in how sentences are related to truth values. While semantics with matrices construe models or valuations as functions mapping sentences’ truth values, relational semantics employ a binary relation $\rho$ between sentences and truth values. Thus, $\phi \rho 1$ may mean that $\phi$ is true, and $\phi \rho 0$ may means that $\phi$ is false. A truth value gap is represented by the fact that neither $\phi \rho 1$ nor $\phi \rho 0$ hold; and truth value glut is represented by the fact that both $\phi \rho 1$ and $\phi \rho 0$ hold.

2. A semantics that employs an accessibility relation between possible worlds, e.g., Kripke semantics.