Formal Systems Concepts

Presented at SMC INCOSE 2006

Joseph J. Simpson and Mary J. Simpson

Abstract: A common conceptual thread that runs through a large portion of systems, systems
engineering, and software engineering literature is explored by this paper.  This conceptual
thread is based on the formal concept of a Moore type of sequential machine (Moore 1956) as
well as the definition of a system and a meta-system. Practical approaches and applications
generated by this common thread are outlined and discussed in terms of complexity reduction,
design efficiency and communication enhancement. Hartmanis and Stearns utilized the abstract
definition of a sequential state machine as a mathematical model of discrete, deterministic
computing devices with finite memory.  These machines have a finite set of inputs, outputs and
internal configurations. Wymore expanded on this work while developing his model-based
systems engineering approach.  In each case, Moore and Wymore, the system concept has the
same form.  The system content; specific inputs, outputs types and transition functions, are
different.  In the software engineering arena, “abstract state machines” and “requirements state
machines” have been developed as formal approaches closely related to Moore state machines. 
This paper presents an expanded systems and meta-systems framework that extends the formal
system concepts.  System abstraction stacks are introduced in this paper.

A link to the PDF presentation slides:Formal Systems Concepts