There are several dozen definitions of this concept. The definition of the concept of a system has changed not only in form but also in substance.
A system is:
- a complex of interacting components (L. von Bertalanffy).
- a set of elements standing in certain relations to one another and to the environment (L. von Bertalanffy).
- a whole that is composed of many parts; an ensemble of attributes (C. Cherry).
- a set of interconnected elements, separated from the environment and interacting with it as a whole (F. I. Peregudov, F. P. Tarasenko).
- an arrangement, set, or collection of things connected or related to each other in such a way that together they form a certain unity, an integrity; an arrangement of physical components connected or related to each other in such a way that they form or act as a unified whole (Distefano).
- a combination of interacting elements organized to achieve one or more stated purposes (ISO/IEC 15288).
- a finite set of functional elements and relations among them, distinguished from its environment in accordance with a specific purpose within a defined time interval (V. N. Sagatovsky).
- a reflection in the consciousness of a subject (researcher, observer) of the properties of objects and their relationships in the task of research and cognition (Yu. I. Chernyak).
- a system S defined on an object A with respect to an integrative property (quality) is a set of such elements, standing in such relations, that give rise to the given integrative property (E. B. Agoshkova, B. V. Akhlibininsky).
- a collection of integrated and regularly interacting or interdependent elements created to achieve specific objectives, where the relationships among elements are defined and stable, and the overall performance or functionality of the system exceeds that of the simple sum of its elements (PMBOK).
- a device that accepts one or more inputs and generates one or more outputs (Drenick).
- a device, process, or scheme that behaves according to some prescription; the function of the system consists in operating over time on information and/or energy and/or matter to produce information and/or energy and/or matter (D. Ellis, F. Ludwig).
- a mathematical abstraction that serves as a model of a dynamic phenomenon (H. Freeman).
- an integrated collection of interacting elements designed for the cooperative performance of a predetermined function (R. Gibson).
- a set of objects together with relationships between the objects and between their attributes (A. Hall, R. Fagen).
- a collection of entities or things, animate or inanimate, that receives certain inputs and acts on them to produce certain outputs, with the aim of maximizing certain functions of inputs and outputs (R. Kershner).
- a region bounded in space and time in which the component parts are connected by functional relationships (J. Miller).
- from a mathematical standpoint, a certain part of the world that at any given time can be described by assigning specific values to a certain set of variables; it is not merely a collection of units (particles, individuals) where each unit is governed by laws of causality acting upon it, but a totality of relations among those units. The more tightly interconnected the relations, the more organized the system formed by those relations (A. Rapoport).
- a set of actions (functions), connected in time and space by a set of practical tasks of decision-making and evaluation of behavior, that is, tasks of management (S. Sengupta, R. Ackoff).
- a term used to denote at least two different concepts: a regular, or ordered, arrangement consisting of elements or parts that are interconnected and act as one whole; a collection, or group of elements (parts), necessary for the performance of some operation (A. Wilson, M. Wilson).
- a nonempty set of elements containing at least two elements, where the elements of this set stand in certain relations and connections to one another (G. Kroeber).
- an abstract system, or simply a system, which is a partially connected set of abstract objects constituting the components of the system. The components of the system may be oriented or unoriented; their number may be finite or infinite; each of them may be defined by a finite or infinite number of basic variables (L. Zadeh, C. Desoer).
- a set of connected acting elements (O. Lange).
- any form of distribution of activity in a chain that is perceived by some observer as regular (G. Pask).
- a set of interrelated components of one kind or another, ordered by relations possessing well-defined properties; this set is characterized by a unity expressed in its integral properties and functions (V. S. Tyukhtin).
- a diversity of relations and connections among the elements of a set that constitutes an integral unity. It makes sense to understand a system as an organized set forming an integral unity (A. D. Ursul).
- a complex of selectively involved components in which the interaction and interrelation of the components take the character of mutual facilitation aimed at obtaining a focused useful result (P. K. Anokhin).
- a collection of real or imaginary elements distinguished in any way from the rest of the world. This collection is a system if: the connections existing among these elements are specified; each element is considered internally indivisible; the system interacts with the world outside it as a whole; when evolving in time, the collection is considered one system if a one-to-one correspondence can be established between its elements at different moments in time. The correspondence must be single-valued, not bijective. Temporal ordering is not a necessary attribute; where divergence occurs, the whole can be considered one system, or subsystems may be distinguished within the system (L. A. Blumenfeld).
- a set of objects on which a predetermined relation with fixed properties is realized. The dual definition is: a system as a set of objects that possess predetermined properties with fixed relations among them (A. I. Uyemov).