diff --git a/encodings/strips/postprocess.lp b/encodings/strips/postprocess.lp new file mode 100644 index 0000000..2aa3fac --- /dev/null +++ b/encodings/strips/postprocess.lp @@ -0,0 +1,61 @@ +% Convert a plan (possibly with parallel actions), given by atoms over occurs/2, +% to a sequential plan, expressed by atoms over sequence/2 + +time(T) :- occurs(A,T). +time :- time(T). + +:- goal(X,V), not initialState(X,V), not time. + +next(T1,T2) :- time(T1), time(T2), T1 < T2, T <= T1 : time(T), T < T2. +init(T2) :- time(T2), #false : next(T1,T2). +stop(T1) :- time(T1), #false : next(T1,T2). + +offset(T2,M) :- time(T2), M = #count{A,T1 : occurs(A,T1), T1 < T2}. +actions(T,N) :- time(T), N = #count{A : occurs(A,T)}. +index(T,M+1..M+N) :- offset(T,M), actions(T,N). + +postcondition(A,X,V) :- postcondition(A,E,X,V), occurs(A,T). +postcondition(A,X) :- postcondition(A,X,V). + +before(A1,A2,T) :- occurs(A1,T), occurs(A2,T), A1 != A2, + precondition(A1,X,V1), postcondition(A2,X,V2), V1 != V2. + +order(A1,A2,T) :- occurs(A1,T), occurs(A2,T), A1 < A2, A <= A1 : occurs(A,T), A < A2. +first(A2,T) :- occurs(A2,T), #false : order(A1,A2,T). + +undone(A,T,M) :- occurs(A,T), offset(T,M). +undone(A,T,N) :- undone(A,T,N-1), select(A1,T,N), A != A1, index(T,N+1). + +done(A,T,N) :- select(A,T,N). +done(A,T,N) :- done(A,T,N-1), index(T,N). + +:- offset(T,M), actions(T,N), occurs(A,T), not done(A,T,M+N). + +holds(X,V,0) :- initialState(X,V), time. +holds(X,V,N) :- select(A,T,N), postcondition(A,X,V). +holds(X,V,N) :- select(A,T,N), holds(X,V,N-1), not postcondition(A,X). + +:- stop(T), offset(T,M), actions(T,N), goal(X,V), not holds(X,V,M+N). + +holds(X,N) :- holds(X,V,N). + +:- holds(X,N), #count{V : holds(X,V,N) } > 1. + +preconditions(A,T,N) :- undone(A,T,N), holds(X,V,N) : precondition(A,X,V). +applicable(A,T,N) :- preconditions(A,T,N), done(A1,T,N) : before(A1,A,T). + +inapplicable(A,T,N) :- done(A,T,N), index(T,N+1). +inapplicable(A,T,N) :- undone(A,T,N), precondition(A,X,V1), holds(X,V2,N), V1 != V2. +inapplicable(A,T,N) :- undone(A1,T,N), before(A1,A,T). + +continue(A2,T,N) :- order(A1,A2,T), inapplicable(A1,T,N), first(A1,T). +continue(A2,T,N) :- order(A1,A2,T), inapplicable(A1,T,N), continue(A1,T,N). + +select(A,T,N+1) :- applicable(A,T,N), first(A,T). +select(A,T,N+1) :- applicable(A,T,N), continue(A,T,N). + +sequence(A,N) :- select(A,T,N). + +% DISPLAY PART + +#show sequence/2.