These are 5 action descriptions with conditional effects:Action(A, Precond:{X}, Effect:{when P : ~X), Z})Action(B, Precond:{Y}, Effect:{when Z : ~P), ~Y,~Z,X})Action(C, Precond:{~Z}, Effect:{when P : ~X), Y})Action(D, Precond:{~X}, Effect:{when Q : X)})Action(E, Precond:{Z}, Effect:{when Q : ~Z)})What state would result from executing the action sequence [E,D,A,B,C] in the state {P,Q,Y,Z}?I know the answer but I really don't know how to achieve it. Anyone please shed some light? (Please include workings)
How to solve this Planning Domain Definition Language (PDDL) question?
artificial intelligence
I will turn my comment into an answer.  Recall that if your state is $\{P,Q,Y,Z\}$, and an effect of an action is $\sim\!Z$ (from now on written $\neg Z$), then the new state will not contain $Z$, i.e., the state will be, if nothing else is an effect, $\{P,Q,Y\}$.Since the question asks what the result of a sequence of actions will be, we need to solve this in the order of that sequence.  The sequence asked was $[E,D,A,B,C]$, and the state was $\{P,Q,Y,Z\}$?  Observe that we by square brackets denote a sequence (i.e., an ordered list) and by curly brackets, an unordered set (the usual kind).Action $E$ in state $\{P,Q,Y,Z\}$:  Precondition $Z$ is good since $Z$ is in the state.  Effect is when $Q$, $\neg Z$.  The new state will thus be $\{P,Q,Y\}$.  We omit writing $\neg Z$ since every element not occurring in the state will be assumed to be not held. Action $D$ in state $\{P,Q,Y\}$:  Precondition $\neg X$ is good.  Effect: when $Q$, $X$.  Hence new state will be $\{P,Q,X,Y\}$.Action $A$ in state $\{P,Q,X,Y\}$:  Precondition is good, $X$ is in the state.  Effect: when $P$, $\neg X$, and $Z$.  $P$ is in the state, hence we remove $X$ and we also add $Z$.  New state is $\{P,Q,Y,Z\}$.Action $B$ in state $\{P,Q,Y,Z\}$: Precondition $Y$ is good.  Effect when $Z$, $\neg P$, also $\neg Y$, $\neg Z$and $X$.  $Z$ is true, hence we lose $P$.  We also lose $Y$ and $Z$ and gain $X$.  New state is $\{Q,X\}$.Action $C$ in state $\{Q,X\}$: Precondition is $\neg Z$, so good.  Effect: when $P$, $\neg X$, and $Y$.  This is the first time we encounter an implication in which the antecedent $P$ is false, so we don't remove $X$.  We still add $Y$, though.  Hence the new, and final state is$$\{Q,X,Y\}.$$