 If \(\bS = \{x_1 , \ldots ,x_n\}\) is a set of values in the range of X, then \(X \in \bS\) is used as shorthand for the disjunction of propositions of the form \(X = x_i\), for \(i = 1,\ldots\), n. Boldface represents ordered sets or vectors. If \(\bX = \{X_1 , \ldots ,X_n\}\) is a vector of variables, and \(\bx = \{x_1 , \ldots ,x_n\}\) is a vector of values, with each value \(x_i\) in the range of the corresponding variable \(X_i\), then \(\bX = \bx\) is the conjunction of propositions of the form \(X_i = x_i\).