### Glossary section: theory The process of forming a set, typically by binding a free variable in a formula which expresses the truth condition, for membership in the set, of the value denoted by the variable. Comprehension and separation are particular kinds of set abstraction. Abstraction to properties (predicates or propositional functions) is analogous. (functional), Forming a function, typically by binding a free variable in an expression which denotes the value of the function for the argument whose value is denoted by the variable. also abstract algebra computer algebra (logic), a proof which proceeds by analysis of the desired conclusion showing that it is derivable from accepted premises (from classical Greece). Such proofs are now sometimes known as a backward or goal oriented proofs. (philosophy), expressing a relationship between concepts. A statement or proposition which lacks empirical content and is true in virtue of its meaning. (philosophy), a kind of philosophy particularly concerned with logical or linguistic analysis (see: Varieties of Philosophical Analysis). theory) definable in second order arithmetic (philosophy), a paradox or contradiction posteriori knowable or justifiable only on the basis of experience priori knowable or justifiable prior to experience based on purely rational considerations also gödelization method a method of doing mathematics in which subject areas are presented and studied as axiomatic theories (computing), a semantics for a programming language given by defining axioms which permit reasoning about the effects of execution of the various parts of a program.