,F │{F#=<0},E │{E\=turn_off}) :-
                                                   <ul>
                                                     <li> 
                                                       F #< D,
                                                     </li>
                                                     <li> 
                                                       not terminates(E │{E\=turn_off},B │{B\=light_on},F │{F#=<0}) :-
                                                      