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Dissertation Information for Tom Carey

NAME:
- Tom Carey
- (Alias) Tomas Todd Carey

DEGREE:
- Ph.D.

DISCIPLINE:
- Computer Science

SCHOOL:
- University of Waterloo, Ontario (Canada) (1980)

ADVISORS:
- None

COMMITTEE MEMBERS:
- None

MPACT Status: Incomplete - Not_Inspected

Title: REACHABILITY IN RESTRICTED CLASSES OF PETRI NETS

Abstract: "A Petri net is an abstract model of control flow in a system of asynchronous activities. The sequences of possible events which can occur in the system are modelled by a sequence of transitions (firing sequence), which produces state changes in the net. We consider here cases of the reachability problem for Petri nets: given a net and initial state, called a marking, can it be determined if there is some firing sequence from the initial marking which leaves the net in a given final marking?

The reachability problem is shown to be decidable for certain classes of nets in which the firing sequences have restrictions forcing the occurrence of events in subsequences to be proportional to their occurrences in the whole sequence, so called bounded ratio (BR) nets. It is also shown that the reachability problem is decidable for nets whose firing sequences can be interpreted as a concatenation of a bounded number of such proportional sequences, general BR nets.

As an example of BR nets, we show that conflict-free nets are BR. As an example of general BR nets, we show that regular nets are general BR. This shows that the concept of ratio bounds can be applied to subclasses with differing restrictions. We conjecture that persistent nets are BR.

The possibility and difficulties of extending the methods developed for general BR nets are discussed."

MPACT Scores for Tom Carey

A = 0
C = 1
A+C = 1
T = 0
G = 0
W = 0
TD = 0
TA = 0
calculated 2008-01-31 06:32:38

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