% AILog representation of some rooms.

% This is the code discussed in Section 12.3.3 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 'before.ail'.

% before(T1,T2) is true if time T1 is before time T2 in a day.

before(am(H1,M1),pm(H2,M2)).
before(am(12,M1),am(H2,M2)) <-
    H2<12.
before(am(H1,M1),am(H2,M2)) <-
    H1<H2 &
    H2<12.
before(am(H,M1),am(H,M2)) <-
    M1<M2.
before(pm(12,M1),pm(H2,M2)) <-
    H2<12.
before(pm(H1,M1),pm(H2,M2)) <-
    H1<H2 &
    H2<12.
before(pm(H,M1),pm(H,M2)) <-
    M1<M2.

% test cases:
% ask before(am(2,30),am(3,10)).
% ask before(am(3,30),am(3,10)).
% ask before(am(3,30),pm(3,10)).
% ask before(am(12,30),am(3,10)).