in a logical information-processing system, a formal semantic system consisting of an alphabet (a list of elementary symbols) and rules of formation, transformation, and interpretation. The formation rules establish which combinations of elementary symbols are allowed, the transformation rules establish which transformations of expressions (in the information language) result in logical inferences, and the interpretation rules specify how expressions composed according to the formation rules should be understood. Since the information language is used in logical information-processing systems to record facts and data, it must be unambiguous, convenient for deductive logical inference and for the identification of identical facts and data written in different form, and suitable for use in an information-processing computer. Such a construction of an information language does not allow all known facts and data to be input to a machine (that would be impossible), but only the essential ones, from which it is possible to obtain the rest by the transformation rules.
The more formalized the real language of a given branch of science (the most formalized languages are used in mathematics and chemistry), the easier it is to create an information language for it. It is necessary to distinguish an information language from an information retrieval language, which is designed for the solution of another, significantly simpler problem—the retrieval of texts (documents) whose basic semantic content answers a certain information request—and therefore has a different structure.
A. I. CHERNYI