KLIR’S REVIEW OF *MODEL-BASED SYSTEMS ENGINEERING*

From the *International Journal of General Systems*, George Klir, Editor, Volume 25, Number 2, pages 179-180, 1996, Gordon and Breach, Amsterdam:

*Model-Based Systems Engineering: An Introduction to the Mathematical Theory of Discrete Systems and to the Tricotyledon Theory of System Design*, by A. Wayne Wymore, CRC Press, Boca Raton FL 33431, 1993 (1 800 272 7737), xiii+710 pages, ISBM 0-8493-8012-X.

Wayne Wymore is now well established as an important leader in systems engineering and a founder of a highly original "school of thought" in the area of systems design. His contribution to this area, which will be the subject of a special issue of this journal in the near future, is best exposed in a trilogy consisting of this book and its two predecessors [Wymore, 1967, 1976]. Wymore’s approach to systems design is characterized by mathematical rigor, comprehensiveness, and broad applicability. This book is, in some sense; the most complete presentation of his approach, even though it is restricted (contrary to its predecessors) to discrete systems.

The book was written as a text for a two-semester course in systems engineering. The restriction to discrete systems was chosen primarily for pedagogical reasons. As stated in the Preface, "The material in the text was chosen to attain three principal objectives:

• to provide the system theoretic foundations necessary to the study and practice of systems engineering,

• to explicate mathematical system theory as the basis for the development of models and designs of large-scale, complex systems consisting of personnel, machines and software and

• to introduce the student to the tricotyledon theory of system design (T3SD) and to the considerations involved in applying the theory to the design of real systems."

The term *tricotyledon theory* was chosen by Wymore early in his writings to name the specific mathematical system theory he developed to facilitate the process of systems design.

The book can be roughly divided into three parts, all approximately the same size. The first part, consisting of Chapters 1-6, covers a general introduction to systems engineering and basic concepts of the tricotyledon theory of system design. The presentation is well organized, all definitions are precise and, yet, sufficiently broad, and the various properties of systems are stated as mathematical theorems and accompanied by appropriate proofs. For example, systems engineering is defined as "the intellectual, academic and professional discipline the principal concern of which is the responsibility to ensure that all requirements for a bioware/hardware/software system are satisfied throughout the life cycle of the system."

The second part of the book, consisting of Chapters 6-9, examines in detail six categories of system design requirements recognized by Wymore. They are:

• input/output requirements

• technology requirements

• performance requirements

• cost requirements

• tradeoff requirements

• system test requirements

This emphasis on design requirements is characteristic of Wymore’s approach and is present in all his other writings as well. The coverage of the six requirement categories is excellent, and indicates Wymore’s extensive experience in practical design of complex systems.

The third part of the book consists of nine appendices. One of the appendices covers in 105 pages the relevant mathematical preliminaries. The other appendices cover notation employed in the tricotyledon theory and examples of systems, design requirements of each of the six categories, and design problems.

In summary, this book is a significant contribution to the literature on systems engineering. The style of writing is very similar to Wymore’s previous books. However, a considerably greater attention is given to pedagogical aspects. I consider the book an outstanding text for courses on system design and I highly recommend it to instructors in these courses.

REFERENCES

Wymore, A. W. [1967] *A Mathematical Theory of Systems Engineering: The Elements*, John Wiley, New York.

Wymore, A. W. [1976] *Systems Engineering Methodology for Interdisciplinary Teams*, John Wiley, New York.

George J. Klir

Center for Intelligent Systems and

Department of Systems Science and Industrial Engineering

Thomas J. Watson School of Engineering and Applied Science

State University of New York

Binghamton NY 13902-6000, USA