Definition:Basic Proposition

Definition
Let $$f: \mathbb B^k \to \mathbb B$$ be a boolean function, where:
 * $$\mathbb B = \left\{{0, 1}\right\}$$ is a boolean domain;
 * $$k\!$$ is a nonnegative integer.

A basic proposition is one of the projection functions $$\operatorname{pr}_j: \mathbb B^k \to \mathbb B$$, defined as follows:

Let $$X = \left({p_1, p_2, \ldots, p_k}\right) \in \mathbb B^k$$.

Then $$\operatorname{pr}_j \left({X}\right) = p_j$$.

That is, a basic proposition is one of the elements of the $k$-tuple $$\left({p_1, p_2, \ldots, p_k}\right)$$.

Also see

 * Literal, which is the same thing from the perspective of propositional logic.