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Lecture 23 – April 11, 2002

Lecture 23 – April 11, 2002. Semester end questions More about Bond agents Models and languages supporting concurrency Petri Nets. Final Exam and Project. The final exam will be Thursday April 25, 7:00 – 9:00 PM in this class room.

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Lecture 23 – April 11, 2002

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  1. Lecture 23 – April 11, 2002 • Semester end questions • More about Bond agents • Models and languages supporting concurrency • Petri Nets

  2. Final Exam and Project • The final exam will be Thursday April 25, 7:00 – 9:00 PM in this class room. • The class project is due on Monday April 22 at 9 AM. See http://www.cs.ucf.edu/~dcm/Spring02Class/Projects.html for a description of the format and contents of project.

  3. Office Hours during the last weeks • I will be out of town Sunday April 14 till Saturday, April 20. • I will be available on • Tuesday, April 24, 3 – 6 PM • Thursday, April 15, 4- 7 PM

  4. Final Exam • Open book • Comprehensive • Two hours • 4-6 problems

  5. Final project presentations • Tuessday – April 16: • 7:00 – 7:20 David Aihe • 7:20 – 7:40 Kiran Anna • 7:40 - 8:00 Temitope Alo • 8:00 - 8:20 Xin Bai • Thursday – April 18 • 7:00 – 7:20 Wafa Elgarath • 7:20 – 7:40 Shan Natarajan • 7:40 – 8:00 Sudipta Rashit • 8:00 - 8:20 Vivek Singh

  6. Final project presentations • Friday – April 19 CS 232 (Seminar Room) • 9:00 – 9:45 John Anthony • 9:45 – 10:30 Brian Hill • 10:30 – 11:15 Mathew Lowerey • 11:15 – 12:00 Aniruddha Tumalla

  7. Agent transformations • Trimming. • Splitting. • Joining.

  8. Place/Transition nets • In 1962 Carl Adam Petri introduced a family of graphs, called Place-Transition, P/T nets to model dynamic behavior of systems. • P/T nets, are bipartite populated with tokens, that flow through the graph. • A bipartite graph is one with two classes of nodes; arcs always connect a node in one class with one or more nodes in the other class. • In the case of P/T nets the two classes of nodes are places and transitions; arcs connect one place with one or more transitions or a transition with one or more places.

  9. P/T nets • Enabling and firing of a transition • Weight of flow relations (arcs). • Marked P/T net • Preset and postset of a transition/place. • Modeling choice and concurrency. • Confusion – symmetric and asymmetric • Marked graph –concurrency but no choice • State graph graph – choice but no concurrency • Inhibitor arcs – modeling priority

  10. P/T nets • Marking  state • Finite/infinite capacity nets • Strict/weak firing rules • Extended P/T nets – P/T nets with inhibitor arcs. • Modeling exclusion.

  11. Properties on P/T nets • Marking independent properties of P/T nets – structural properties • Marking dependent properties of P/T nets.

  12. State machines • Finite state machines can be modeled by a subclass of L-labeled P/T nets called state machines (SM) with the property that • In a SM each transition has exactly one incoming and one outgoing arc or • This topological constraint limits the expressiveness of a state machine, no concurrency is possible.

  13. Marked graphs • In a marked graph each place has only one incoming and one outgoing arc thus marked graphs do no not allow modeling of choice.

  14. Confusion; free-choice and extended free-choice P/T nets. • When choice and concurrency are mixed, we end up with a situation called confusion. • Symmetric confusion means that two or more transitions are concurrent and, in the same time, they are in conflict with another one. • In an extended free-choice net if two transition share an input place they must share all places in their presets. In an asymmetric choice net two transitions may share only a subset of their input places.

  15. Marking dependent properties • Liveness • Boundedness • Safety • Refersibility

  16. Firing sequence • Firing sequence • Rechability analysis

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