Aletta Nylén

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We consider (unbounded) Timed Petri Nets (TPNs) where each token is equipped with a real-valued clock representing the “age” of the token. Each arc in the net is provided with a subinterval of the natural numbers, restricting the ages of the tokens travelling the arc. We apply a methodology developed in [AN00], based on the theory of better quasi orderings(More)
Many existing algorithms for model checking of in nite-state systems operate on constraints which are use d to represent (potentially in nite) sets of states. A gener alpowerful technique which can be employed for proving termination of these algorithms is that of w ell quasi-orderings. Several methodolo gies have been pr op ose d for derivation of new well(More)
Net unfoldings have attracted great attention as a powerful technique for combating state space explosion in model checking, and have been applied to verification of finite state systems including 1-safe (finite) Petri nets and synchronous products of finite transition systems. Given that net unfoldings represent the state space in a distributed, implicit(More)
We consider verification of safety properties for concurrent real-timed systems modelled as timed Petri nets, by performing symbolic forward reachability analysis. We introduce a formalism, called region generators for representing sets of markings of timed Petri nets. Region generators characterize downward closed sets of regions, and provide exact(More)
During the past two years, Massive Open Online Courses (MOOCs) have created wide interest in the academic world raising both enthusiasm for new opportunities for universities and many concerns for the future of university education. The discussion has mainly appeared in non-scientific forums, such as magazine articles, columns and blogs, making it difficult(More)
ion of a control task with a specified period and a fixed input-output latency shorter than the period. Individual tasks can be combined into more complex components without loss of their individual guaranteed fixed-latency properties. I/O occurs at fixed predefined points in time, at which inputs are read or controller outputs become visible. The control(More)