Horst F. Wedde
An Exercise in Flexible Formal Modeling under Realistic Assumptions
Systems Research, Nr. 1 (2), 1984
A brief introduction into the Theory of Interaction Systems is given. This is an innovative general formal tool for adequately modeling very large and complex dynamical systems (distributed systems). The formalism is purely built on interaction primitives. In order to demonstrate its possible use as a modeling and communication tool for the design and development phase of a large real modeling/reorganization process a developing elevator problem is defined and discussed which adequately reflects essential aspects of a real modeling process: Uncertainty of observations, partial autonomy of subsystems, limited range of decisions or of responsibility, interrelation of requirements on different design levels, partial reorganization/redesign. A formal solution is constructed for this problem in various iterative steps using standard constructions which describe the local change of requirements and which have a well-defined global effect without influencing, or changing, the formal specification at, or for, distant locations or activities. So we prove the adequacy of our tools regarding the mentioned modeling aspects, in particular their flexibility. It is explained how the formal approach of interaction systems may help to constitute innovative forms of formal reasoning and of systems thinking needed for a practice-oriented systematic way of solving organizational/design problems in large real systems.