propositional function

propositional function

Sentencelike expression that may be thought of as obtained from a sentence by substituting variables for constants occurring in the sentence. For example, “x was a parent of y” may be thought of as obtained from “Adam was a parent of Abel.” A propositional function therefore has no truth-value, becoming true or false only when its free variables are replaced by constants of appropriate syntactic categories (e.g., “Abraham was a parent of Isaac”).

---

propositional function [‚präp·ə¦zish·ən·əl ′fəŋk·shən]

(mathematics)

An expression that becomes a proposition when the values of certain symbols in the expression are specified, and that is either true or false depending on these values. Also known as logical function; open sentence; open statement; predicate; sentential function; statement function.