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PEAR: Petri-net Evolution Analysis Report

Table of contents

Description

PEAR is a Python program that takes advantage of Petri nets and logical conditions to develop a screening tool aimed at studying the effect of perturbations in interconnected systems.

Petri nets

A Petri net is a mathematical model that allows the representation and description of a process, but also the modeling of the process evolution in terms of its new state after the occurrence of a perturbation event. Edges in the graph, called arcs (graphycally represented as arrows), are directed and connect places (graphycally represented as circles) to transitions (graphycally represented as rectangles) or transitions to places. To simulate a dynamic process, a number of tokens is assigned to each place in order to indicate the presence of some quantitative property. This assignment of tokens to places encodes the state of the system and is called a marking. The tokens move among the places when some event happens (transition firing). A transition can only fire when it is enabled, meaning that each of its input places has at least one token in the current marking. The firing of a transition is triggered by a specific event that occurs in the environment. The order in which events are generated depends upon the event which generates them and the hyerarchy of the system. When a transition fires, it removes one token from each place connected by input arcs and gives one token to each place connected by output arcs until a stop condition is met.

Dependencies and installation

PEAR requires snakes.

Installing from source

You can clone the repository using

> git clone https://github.com/auroramaurizio/PEAR

To install the package just type:

> python setup.py install

To uninstall the package you have to rerun the installation and record the installed files in order to remove them:

> python setup.py install --record installed_files.txt
> cat installed_files.txt | xargs rm -rf

Authors

License

See the LICENSE file for license rights and limitations (MIT).