A MODIFIED REACHABILITY TREE APPROACH TO ANALYSIS OF

UNBOUNDED PETRINETS

Instructor: Prof. Lingxi liCourse: Introduction to Discrete Event Dynamic Systems Presented by: Anirudh

ECE-595 Spring 2013 Critiques Seminar

Reachability Tree a fundamental tool to investigate properties of PN’s

Distinguishing FRT from MRT:

Preliminaries:

• w-number: Introduces w-number notion that provides more information. S=Kwn+q.• Addition of w-numbers and integers.• Comparison of two w-vectors.• Calculation of next state function.• Association of w-number components.• Conditionally enabled.• Classification of nodes:

Interior. Terminal. Duplicate. w-duplicate.

MRT Algorithm Generation:

FRT for PNI and PN2

MRT for PN2

MRT for PN1

PN1

PN2

EXAMPLE FOR MRT TO SOLVE REACHABILTY PROBLEM:

PN

FRT for PNMRT for PN

EXAMPLE FOR MRT TO SOLVE DEADLOCK PROBLEM:

Conclusions:

• MRT provides more information on structure of infiniteness on introducing w-number.

• MRT provides the powerful reachability set of unbounded petrinets.

• A useful algorithm that solves deadlock and reachability problems.

• MRT’s deadlock and reachabilty analysis vital for many applications.