## Variables

Most ordinary letters are accepted as variables. These may be subscripted or superscripted so long as it is understood that the variable formed is not semantically compound. For example "x_i" can be used for "x-inner" if no reference to a variable "i" is intended. For most mathematical purposes these variables are all that is needed.

Symbolic logic expressions and some definitions require some special kinds of variables shown here:
 \pvar - \tvar Sentential Variables \ppvar -\ttvar More Sentential Variables \pbar - \rbar Unary Predicate Variables \pbarp - \rbarp Binary Predicate Variables \pbarpp - \rbarpp Ternary Predicate Variables \ubar - \wbar Unary Function Symbol Variables \ubarp - \wbarp Binary Function Symbol Variables \ubarpp - \wbarpp Ternary Function Symbol Variables

Examples:

(\pvar \Iff \qvar \c (\pvar \c \qvar))

(x = y \c \pbar x \Iff \pbar y)

(x \in \setof t \pbar t \Iff \pbar x \and x \in \U)