\begin{definition}[Definition:Basic Proposition]
Let $f: \mathbb B^k \to \mathbb B$ be a boolean function, where:
:$\mathbb B = \set {0, 1}$ is a boolean domain
:$k$ is a natural number.
A '''basic proposition''' is one of the projection functions $\pr_j: \mathbb B^k \to \mathbb B$, defined as follows:
Let $X = \tuple {p_1, p_2, \ldots, p_k} \in \mathbb B^k$.
Then:
:$\map {\pr_j} X = p_j$
That is, a '''basic proposition''' is one of the elements of the $k$-tuple $\tuple {p_1, p_2, \ldots, p_k}$.
\end{definition}