6stoppedIn(T1, Fluent, T2) :-
    7    time(T),
    8    time(T2),
    9    time(T1),
   10    T1 < T, T < T2,
   11    terminates(Event, Fluent, T),
   12    happens(Event, T).
   13
   14stoppedIn(T1, Fluent, T2) :-
   15    time(T),
   16    time(T2),
   17    time(T1),
   18    T1 < T, T < T2,
   19    releases(Event, Fluent, T),
   20    happens(Event, T).

   23startedIn(T1, Fluent, T2) :-
   24    time(T),
   25    time(T2),
   26    time(T1),
   27    T1 < T, T < T2,
   28    initiates(Event, Fluent, T),
   29    happens(Event, T).
   30
   31startedIn(T1, Fluent, T2) :-
   32    time(T),
   33    time(T2),
   34    time(T1),
   35    T1 < T, T < T2,
   36    releases(Event, Fluent, T),
   37    happens(Event, T).
   38
   39%% BEC3 - HoldsAt(f,t)
   40holdsAt(Fluent2, T2) :-
   41    time(T2),
   42    initiates(Event, Fluent1, T1),
   43    happens(Event, T1),
   44    trajectory(Fluent1, T1, Fluent2, T2),
   45    not stoppedIn(T1, Fluent1, T2).
   46
   47%% BEC4 - HoldsAt(f,t)
   48holdsAt(Fluent, T) :-
   49    time(T),
   50    0 < T,
   51    initiallyP(Fluent),
   52    not stoppedIn(0, Fluent, T).
   53
   54%% BEC5 - not HoldsAt(f,t)
   55-holdsAt(Fluent, T) :-
   56    time(T),
   57    0 < T,
   58    initiallyN(Fluent),
   59    not startedIn(0, Fluent, T).
   60
   61%% BEC6 - HoldsAt(f,t)
   62holdsAt(Fluent, T) :-
   63    time(T),
   64    initiates(Event, Fluent, T1),
   65    happens(Event, T1),
   66    T1 < T,
   67    not stoppedIn(T1, Fluent, T).
   68
   69%% BEC7 - not HoldsAt(f,t)
   70-holdsAt(Fluent, T) :-
   71    time(T),
   72    terminates(Event, Fluent, T1),
   73    happens(Event, T1),
   74    T1 < T,
   75    not