Reconstruction of Concurrent System Models Described by Decomposed Data Tables

This paper deals with reconstruction of net models of concurrent systems described by information systems changing in time. Constructed net models have the form of coloured Petri nets. Resulting nets are constructed on the basis of decomposed information systems. In many practical cases, a description of modelled systems changes in time. New knowledge about structures and behaviours of systems appears. When new descriptions appear, the net models should be changed taking into consideration the new knowledge. An approach to reconstruction of net models is here presented. One of many possible cases is considered, i.e., when the new global state of the modelled system appears. The ability to compute reducts and components of a new information system, being a new description of a modelled system, in an efficient way is important for reconstruction. Therefore, some propositions and corollaries useful to compute reducts of a new information system on the basis of reducts of an old information system are given. These propositions and corollaries are the basis to formulate algorithms for computing new reducts and components. Moreover, a way to determine the cost of the reconstruction of a net model is given. The cost of the reconstruction is treated as the cost of adding new functional modules, communication lines or their modifications. The discussed approach to model reconstruction extends and refines that proposed by Z. Suraj in 1998. An example is given in this paper to illustrate the presented idea.