tic_tac_toe.lp

player(x).
player(o).
#domain player(P).

next(x,o).
next(o,x).

first_player(x).

{ happens(mark(P,C),T) } :-
	holds_at(turn(P),T),
	holds_at(blank(C),T),
  not happens(victory(Pp),T),
	next(Pp,P).

cell(0;1;2;
     3;4;5;
     6;7;8).
#domain cell(C).

event(mark(P,C)).
event(victory(P)).

fluent(blank(C)).
fluent(marked(P,C)).
fluent(turn(P)).

holds_at(blank(C),0).

-holds_at(marked(P,C),0).

holds_at(turn(P),0) :- first_player(P).
-holds_at(turn(P),0) :- not holds_at(turn(P),0).

-released_at(F,0).

initiates(mark(P,C),marked(P,C),T).
terminates(mark(P,C),blank(C),T).

initiates(mark(P,C),turn(Pn),T) :- next(P,Pn).
terminates(mark(P,C),turn(P),T).


happens(victory(P),T) :-
	holds_at(marked(P,C1),T),
	holds_at(marked(P,C2),T),
	holds_at(marked(P,C3),T),
	cell(C1;C2;C3),
	trigger(C1,C2,C3).


trigger(0,1,2). % -
trigger(3,4,5). % -
trigger(6,7,8). % -
 
trigger(0,3,5). % |
trigger(1,4,7). % |
trigger(2,5,8). % |

trigger(0,4,8). % \
trigger(6,4,5). % /


#const t_max=3.
timepoint(0..t_max).

:- 2 { happens(Ev,T) :event(Ev) }.
:- 0 { happens(Ev,T) :event(Ev) } 0.