 An important notion in probability theory is that of conditional probability, that is, the probability of a proposition \(A\) conditional on a proposition \(B\), in symbols, \(\Pr( A\pmid B)\). Although it is sometimes taken as a primitive notion, conditional probability is usually defined as the probability of the conjunction \(\Pr(A \wedge B)\) divided by the probability of the proposition being conditioned on, \(\Pr(B)\), or in other words, 