Axiomatizing the algebra of net computations and processes:
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Bibliographische Detailangaben
Beteiligte Personen: Degano, Pierpaolo 1950- (VerfasserIn), Meseguer, José (VerfasserIn), Montanari, Ugo 1943- (VerfasserIn)
Format: Buch
Sprache:Englisch
Veröffentlicht: Stanford, Calif. 1990
Schriftenreihe:Computer Science Laboratory <Menlo Park, Calif.>: SRI-CSL 90,12
Schlagwörter:
Abstract:Abstract: "Descriptions of concurrent behaviors in terms of partial orderings (called nonsequential processes or simply processes in Petri net theory) have been recognized as superior when information about distribution in space, about causal dependency or about fairness must be provided. However, at least in the general case of Place/Transition (P/T) nets, the proposed models lack a suitable, general notion of sequential composition. In this paper, a new algebraic axiomatization is proposed, where, given a net N, a term algebra P[N] with two operations of parallel and sequential composition is defined. The congruence classes generated by a few simple axioms are proved isomorphic to slight refinement of classical processes
Actually, P[N] is a symmetric monoidal category, parallel composition is the monoidal operation on morphisms and sequential composition is morphism composition. Besides P[N], we introduce a category S[N] containing the classical occurrence and step sequences. The term algebras of P[N] and of S[N] are in general incomparable, and thus we introduce two more categories K[N] and T[N] providing an upper and a lower bound, respectively. A simple axiom expressing the functoriality of parallel composition allows us to map K[N] to P[N] and S[N] to T[N], while commutativity of parallel composition maps K[N] to S[N] and P[N] to T[N] (see Figure 4)
Morphisms of K[N] constitute a new notion of concrete net computation, while the strictly symmetric monoidal category T[N] was introduced previously by two of the authors as a new algebraic foundation for P/T nets [13]. In the context of the present paper, the morphisms of T[N] are proved isomorphic to the processes recently defined in terms of the 'swap' transformation by Best and Devillers [4]. Thus the diamond of the four categories gives a full account in algebraic terms of the relations between interleaving and partial ordering observations of P/T net computations.
Umfang:23 S.