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%%%%% A reader and his "switcher" friend
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%%% The switcher and the reader are at the door.
%%% The light is switched off
%%% The reader wish to read the book on the table
%%% He needs 5 (sequential) minutes to end the reading of the book
%%% The light must be on for reading, of course
%%% The power switch is in a house corner
%%% When switched on, light turns off automatically after two minutes 
%%% (Therefore the switcher need switching-on it again).
%%% The move point2point actions have different lengths.
%%% The goal is to allow the reader to end the reading of the book
%%% and to put the switcher in the same place as the reader
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%%% Developped and encoded by DFP, May 2010
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%%% You'll discover the plan with :-bmap(9).
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%%%%%%%%% WARNING !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
%%% set loopcontrol to off in BMAP (needed at the beginning of the plan)
%%% Otherwise, add a faked fluent to ensure all states are different
%%% simply uncommenting the following line
%%% fluent(time,0,100). initially(time eq 0). caused([],time ++).
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agent(switcher).
agent(reader).

%%% positions:
%% 1. door - 2. switch - 3. table 

position(1).
position(2).
position(3).

%%%%

fluent(at(X),1,3) :- agent(X).
fluent(light_on,0,1).
fluent(all_read,0,1).

%%%%%%%% ACTION with duration %%%%%%%%

action([X], move(1,2), 3) :-  agent(X).
action([X], move(2,1), 3) :-  agent(X).
action([X], move(1,3), 4) :- agent(X).
action([X], move(3,1), 4) :- agent(X).
action([X], move(2,3), 1) :-  agent(X).
action([X], move(3,2), 1) :-  agent(X).

action([switcher], switch_on, 1).

action([reader], read, 1).
       
%%%%%%%% EXECUTABILITY %%%%%%%%

executable([X], move(A,B), [at(X) eq A]) :-
     action([X], move(A,B),_).
     
executable([switcher], switch_on, [at(switcher) eq 2]).
executable(  [reader], read,      [at(reader) eq 3,   light_on eq 1]).

%%%%%%%% EFFECTS  %%%%%%%%

causes(light_on eq 1, [actocc([switcher], switch_on)],2).

causes(light_on eq 0, [actocc([switcher], switch_on)^(-1) eq 0,
                       actocc([switcher], switch_on) eq 0],1).

causes(all_read eq 1, 
    [actocc([reader], read)^(-4),
     actocc([reader], read)^(-3),
     actocc([reader], read)^(-2),
     actocc([reader], read)^(-1),
     actocc([reader], read)      ]).
     
causes(at(X) eq B, 
    [actocc([X],move(A,B))^(Dneg) gt actocc([X],move(A,B))^(Dmeg)]) :- 
    action([X],move(A,B),D), Dmeg is -D, Dneg is 1-D.
   
                   
%%%%%%%% Initial State and Goal

initially(at(X) eq 1) :- agent(X).
initially(light_on eq 0).
initially(all_read eq 0).

%%%%%

goal(all_read eq 1).
goal(at(switcher) eq at(reader)).

%%% This minimizes the unessential switch-on actions

plan_cost(plan leq 16).

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