=================================================================
Logtalk - Object oriented extension to Prolog
Release 2.22.1
Copyright (c) 1998-2004 Paulo Moura. All Rights Reserved.
To load this example and for sample queries, please see the SCRIPT file.
In this example we have several types of polygons that can be concentric.
This is represented by a concentric binary relation ensuring that whenever
a polygon is moved towards a new position, all polygons likewise concentric
are moved along with them.
