Partial Order Plan <Actions, Orderings Links> Start At(Home) sells(hws Drill) Sells(SM, Milk) Sells(SM, Ban. At(Home Go(HW At(HWS) Sells(hwS, Drill Buy(Drill At(HWs GO(SM) At(SM), Sells(Sm,Milk) At(Sm), Sells(SM, Ban. Buy(Milk) Buy(Ban. AtaMI Go(Home) Have milk) at(Home) Havel Ban ) Have(drill) Finish
Start Go(HWS) Go(Home) Finish Buy(Drill) Buy(Milk) Buy(Ban.) Go(SM) Have(Milk) At(Home) Have(Ban.) Have(Drill) At(SM), Sells(SM,Milk) At(SM) At(SM), Sells(SM,Ban.) At(Home) At(HWS) At(HWS) Sells(HWS,Drill) At(Home) Sells(HWS,Drill) Sells(SM,Milk) Sells(SM,Ban.) Partial Order Plan <Actions,Orderings,Links>
Partial Order planning Partial Order planning problem Problem Encoding Partial Order plans Plan correctness Partial order plan generation Plan execution and monitoring
Partial Order Planning – Partial Order Planning Problem • Problem Encoding • Partial Order Plans • Plan Correctness – Partial Order Plan Generation – Plan Execution and Monitoring
What constitutes a correct plan? Complete Plan Achieves all goals At(Home) Sells(HWS, Drill) Sells(SM, Milk) Sells(SM, Ban. Achieves all preconditions No actions intervenes to undo needed precondition At(HWS) Sells(HWS, Drill Buy(Drill) · Consistent plan HWS GO(SM There exists an execution At(SM) Sells( SM Milk) At(SM), Sells(SM, Ban. Buy(Ban) sequence that is consistent with the ordering Have(milk)At(Home)Have( Ban. Have( drill)
What Constitutes a Correct Plan? • Complete Plan – Achieves all Goals • Achieves all preconditions … • No actions intervenes to undo needed precondition • Consistent Plan – There exists an execution sequence that is consistent with the ordering Start Go(HWS) Go(Home) Finish Buy(Drill) Buy(Milk) Buy(Ban.) Go(SM) Have(Milk) At(Home) Have(Ban.) Have(Drill) At(SM), Sells(SM,Milk) At(SM) At(SM), Sells(SM,Ban.) At(Home) At(HWS) At(HWS) Sells(HWS,Drill) At(Home) Sells(HWS,Drill) Sells(SM,Milk) Sells(SM,Ban.)
Why is an ordering needed? At(HWS GO(SM) At(SM), not At(HWS) At(SM Buy(Milk) AtISML Go(Home At(Home), not At(SM)
Why is an ordering needed? Go(Home) Buy(Milk) Go(SM) At(Home), not At(SM) At(SM) At(SM) At(HWS) At(SM), not At(HWS)
Why is an ordering needed? Suppose the other order is allowed what happens At(HWS GO(SM) At(SM), not At(HWS) Threatened AtISML Precondition G OfHome At(Home), not At(SM) At(SML Buy(Milk)
Why is an ordering needed? Go(Home) At(Home), not At(SM) At(SM) Buy(Milk) At(SM) Suppose the other order is allowed, what happens? “Threatened Precondition” Go(SM) At(HWS) At(SM), not At(HWS)