In formal logic, a formal system (also called a logical system,[1] a logistic system,[1] a logical calculus,[2] or simply a logic[1]) consists of a formal language together with a deductive system (also called a deductive apparatus) which consists of a set of inference rules and/or axioms. A formal system is used to derive one expression from one or more other expressions antecedently expressed in the system. These expressions are called axioms, in the case of those previously supposed to be true, or theorems, in the case of those derived. A formal system may be formulated and studied for its intrinsic properties, or it may be intended as a description (i.e. a model) of external phenomena.
Contents |
|
