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Author: Admin | 2025-04-27
Full reachability graph because in the current final marking, [p2], t3 is still enabled.Total0.00 / 0.50Question ExplanationHow to construct a reachability graph is explained in more detail in the lecture 'Petri Nets (2/2)' of week 2.Question 4Which of the following Petri nets best describes the following process of treatment of a patient at a dentist? If we look at the patient separately, then each patient can be in one of five states: the patient is at home (state "p_home"),the patient is sitting in the waiting room (state "p_wait"), the patient is treated (state "p_treat"),the treatment is finished (state "p_done"), and the patient has left the practice (state "p_left").There are four events: the patient enters the practice ("enter"); the treatment starts ("start"); thetreatment is documented ("docu"); and the treatment ends ("end"). The dentist can be in threestates: "d_free", "d_busy", and "d_docu". There are three respective events: "start", "docu", and"end". The nurse can be either in state "n_free" or in state "n_busy". There are two events wherethe nurse is involved: "start" and "docu". Finally, there is also a secretary involved. Either shesits at the reception (state "s_reception") or she helps the dentist documenting the treatment andwriting a prescription (state "s_docu"). For the documentation, there are two events relevant:"docu" and "end". Furthermore, when a patient enters the practice, the secretary is taking careof the reception. Suppose that initially there are two patients at home, the dentist and the nurseare in state "free", and the secretary is sitting at the reception.Note that you can click on the process models shown to enlarge them.Your AnswerScoreExplanationCorrect0.50This Petri net indeed makes sure that the patient, dentist, secretary and nurse are utilized correctly and made available when they are not busy any more.Total0.50 / 0.50Question ExplanationMore examples of how to model certain processes based on their descriptions are discussed in the lecture 'Petri Nets (2/2)' in week 2.Question 5Given the Petri net below, which of the following properties hold:Your AnswerScoreExplanationAll places are bounded.Correct0.10All places, and therefore the Petri net, are indeed bounded since at no point in time p1 or p2 contains more than 3 tokens.All places are safe.Correct0.10A place is safe when it is 1-bounded, which is not the case here since both places are 3-bounded.The marked Petri net has a reachable dead marking.Correct0.10The Petri net contains a deadlock since t3 can remove all tokens from the Petri net after which no further transition is enabled.All transitions are liveCorrect0.10None of the transitions are live since there is a reachable marking, the empty marking, after which none of the transitions are enabled.All transitions are dead.Correct0.10Not all transitions are dead since in the initial marking transition t1 is enabled.Total0.50 / 0.50Question ExplanationDifferent Petri net properties are discussed in 'Transition
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