% AILog code to demonstrate default reasoning.

% This is the code discussed in Example 5.27 of Section 5.5.1 of Poole
% and Mackworth, Artificial Intelligence: foundations of computational
% agents, Cambridge, 2010.

% Copyright (c) David Poole and Alan Mackworth 2009. This program
% is released under GPL, version 3 or later; see http://www.gnu.org/licenses/gpl.html

% To run this in AILog, you should put it in the same directory as AILog and then call
% load 'beach.ail'.

away_from_beach <- ~ on_beach.
beach_access <- on_beach & ~ab_beach_access.
swim_at_beach <- beach_access & ~ab_swim_at_beach.
ab_swim_at_beach <- enclosed_bay & big_city & ~ab_no_swimming_near_city.
ab_no_swimming_near_city <- in_BC & ~ab_BC_beaches.

% some queries commands to try:
% ask away_from_beach.
% ask beach_access.
% tell beach_access.
% ask away_from_beach.
% ask swim_at_beach.
% tell enclosed_bay.
% ask swim_at_beach.
% tell big_city.
% ask swim_at_beach.
% tell in_BC.
% ask swim_at_beach.