The on-line interpreter in Prolog (the main loop).

online(P,S,H,Pol,U) :-  
               incrBestDo(P,S,H,ProgRemaining,Pol1,U1,Prob1),
( final(ProgRemaining,S,H,Pol1,U1), Pol=Pol1, U=U1 ;
  reward(R,S),  Pol1 = (A : Rest),
 ( agentAction(A), deterministic(A,S),
     doReally(A),         /* execute A in reality*/
       !,                /* commit to the result */
     senseExo(do(A,S), SE),   /* exogenous actions, if any */
     decrement(H, Hor),
     online(ProgRemaining,SE,Hor,PolFut,UFut), 
     Pol=(A : PolFut), U is R + UFut  ;  /* Or */
   senseAction(A),
     doReally(A),          /* do sensing */
       !,                /* commit to results of sensing*/
     senseExo(do(A,S), SE),   /* exogenous actions, if any */
     decrement(H, Hor),
     online(ProgRemaining,SE,Hor,PolFut,UFut),
     Pol=(A : PolFut), U is R + UFut  ;  /* Or */
   agentAction(A), stochastic(A,S,List),
     doReally(A),            /* execute A in reality*/
       !,                 /* commit to the result */   
     senseEffect(A,S,SEff), 
     diagnose(SEff,List,SN),    /* Find what happened */
     senseExo(SN, SE),      /* exogenous actions, if any */
     decrement(H, Hor),
     online(ProgRemaining,SE,Hor,PolFut,UFut), 
     Pol=(A : PolFut), U is R + UFut 
  ) 
).