In: Technical Report TR93-7, Computer Science Department, University of Tasmania. 1993.
Abstract: Hierarchical Coloured Petri Nets provide a powerful technique for modelling concurrent systems. The colouring of tokens avoids the need for unnecessarily duplicating the control structure of the net, as is the case for the simpler place/transition nets. The decomposition of complex nets is further encouraged by the provision of hierarchy constructs, whereby a subnet can be isolated as a separate page. It is common to find substitution transitions and place fusion sets implemented as the hierarchy constructs of coloured petri net tools. This paper examines the provision of substitution places and considers why this construct has not been more popular. It suggests an improved semantics for the construct to that originally proposed; it proposes a desirable extension; and it considers the contexts where this sort of construct would be most desirable