Diploma Thesis. Université Libre de Bruxelles, Belgium, 1990.
Abstract: The paper is mainly concerned with establishing satisfying equivalence relations for Petri nets and COSY systems. The approach in section 1 is sequential: Petri nets and COSY path programs are described in terms of their languages; several language equivalences are defined; the section is concluded with a criticism of the inability of these equivalences to reflect concurrency. The approach in section 2 is concurrent (but nonetheless based on the sequential concepts introduced in section 1): Petri nets and COSY systems are described in terms of the languages of their refinements; the shortcomings (concerning concurrency) of equivalences introduced in section 1 are corrected.
Keywords: language; refinement; equivalence relation (for nets and) COSY systems; COSY path program language; net language; language equivalence; language (of) refinement.