Loading ...
Sorry, an error occurred while loading the content.
 

POP Planner Implementation: Choose-Operator

Expand Messages
  • yougooh2000
    Hi, I am attempting to implement the POP planner as is described in AIMA s 1st version (Chap. 11.). I am having doubts regarding the call choose-operator
    Message 1 of 7 , Dec 11, 2003
      Hi,

      I am attempting to implement the POP planner as is described in AIMA's
      1st version (Chap. 11.). I am having doubts regarding the call
      "choose-operator" that is described in the book. The
      pseudo-code says
      that if the step to add (S-add) is selected from operator's list (not
      the plan), then it is necessary to:
      1)Add this new step to the plans already existing steps.
      2)Add the ordering: Start < S-add < Finish

      I cannot understand what is the need for step 2). Say for example I
      start the planner with a minimal plan of {Start, Finish} and on
      selecting the first operator, I only find an S-add from the operator's
      list. I will have to add the ordering S-add < S-need, where S-need =
      Finish, according to the 5th pseudo-code line of the call. After that
      I see that I have to execute steps 1 and 2 as described above. Now I
      have a _repeated_ attempt to add ordering S-add < Finish.

      I have considered not doing step 2) which would result in a missing
      ordering Start < S-add. I figure this will eventually be added to the
      orderings when I process step S-add (i.e: attempt to satisfy its
      pre-conditions).

      Am I missing something?

      TIA.
      Hugo Ferreira.
    • E etech058
      Hello, Which language will you use for implementation? Best regards/chenyu ... From: yougooh2000 [mailto:hugo.ferreira@mail.telepac.pt] Sent:
      Message 2 of 7 , Dec 11, 2003
        Hello,
        Which language will you use for implementation?

        Best regards/chenyu

        -----Original Message-----
        From: yougooh2000 [mailto:hugo.ferreira@...]
        Sent: 2003年12月12日 0:06
        To: aima-talk@yahoogroups.com
        Subject: [aima-talk] POP Planner Implementation: Choose-Operator

        Hi,

        I am attempting to implement the POP planner as is described in AIMA's
        1st version (Chap. 11.). I am having doubts regarding the call
        "choose-operator" that is described in the book. The
        pseudo-code says
        that if the step to add (S-add) is selected from operator's list (not
        the plan), then it is necessary to:
        1)Add this new step to the plans already existing steps.
        2)Add the ordering: Start < S-add < Finish

        I cannot understand what is the need for step 2). Say for example I
        start the planner with a minimal plan of {Start, Finish} and on
        selecting the first operator, I only find an S-add from the operator's
        list. I will have to add the ordering S-add < S-need, where S-need =
        Finish, according to the 5th pseudo-code line of the call. After that
        I see that I have to execute steps 1 and 2 as described above. Now I
        have a _repeated_ attempt to add ordering S-add < Finish.

        I have considered not doing step 2) which would result in a missing
        ordering Start < S-add. I figure this will eventually be added to the
        orderings when I process step S-add (i.e: attempt to satisfy its
        pre-conditions).

        Am I missing something?

        TIA.
        Hugo Ferreira.



        To unsubscribe from this group, send an email to:
        aima-talk-unsubscribe@yahoogroups.com



        Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
      • yougooh2000
        Hi, First versions will (hopefully) be in Prolog. This is for research purposes. Regards, Hugo. ... AIMA s ... (not ... operator s ... that ... the ...
        Message 3 of 7 , Dec 12, 2003
          Hi,

          First versions will (hopefully) be in Prolog. This is for research
          purposes.

          Regards,
          Hugo.


          --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...> wrote:
          > Hello,
          > Which language will you use for implementation?
          >
          > Best regards/chenyu
          >
          > -----Original Message-----
          > From: yougooh2000 [mailto:hugo.ferreira@m...]
          > Sent: 2003Äê12ÔÂ12ÈÕ 0:06
          > To: aima-talk@yahoogroups.com
          > Subject: [aima-talk] POP Planner Implementation: Choose-Operator
          >
          > Hi,
          >
          > I am attempting to implement the POP planner as is described in
          AIMA's
          > 1st version (Chap. 11.). I am having doubts regarding the call
          > "choose-operator" that is described in the book. The
          > pseudo-code says
          > that if the step to add (S-add) is selected from operator's list
          (not
          > the plan), then it is necessary to:
          > 1)Add this new step to the plans already existing steps.
          > 2)Add the ordering: Start < S-add < Finish
          >
          > I cannot understand what is the need for step 2). Say for example I
          > start the planner with a minimal plan of {Start, Finish} and on
          > selecting the first operator, I only find an S-add from the
          operator's
          > list. I will have to add the ordering S-add < S-need, where S-need =
          > Finish, according to the 5th pseudo-code line of the call. After
          that
          > I see that I have to execute steps 1 and 2 as described above. Now I
          > have a _repeated_ attempt to add ordering S-add < Finish.
          >
          > I have considered not doing step 2) which would result in a missing
          > ordering Start < S-add. I figure this will eventually be added to
          the
          > orderings when I process step S-add (i.e: attempt to satisfy its
          > pre-conditions).
          >
          > Am I missing something?
          >
          > TIA.
          > Hugo Ferreira.
          >
          >
          >
          > To unsubscribe from this group, send an email to:
          > aima-talk-unsubscribe@yahoogroups.com
          >
          >
          >
          > Your use of Yahoo! Groups is subject to
          http://docs.yahoo.com/info/terms/
        • E etech058
          Hello, I have read the pecudo code again give you my thinking here. If you delete the step 2) (start
          Message 4 of 7 , Dec 17, 2003

            Hello,

            I have read the pecudo code again give you my thinking here. If you delete the step 2) (start < s-add < finish), the following problem will happens, To make the discussion more clearly, I give the context (To simplify the problem, I will ignore the variables):

            Context:

            1.      actions

            a)       action1

                                    i.              name:                 start

                                  ii.              precondition:      nothing

                                iii.              effect:                  nothing

            b)       action2

                                    i.              name:                 finish

                                  ii.              precondition:      predicate

                                iii.              effect:                  nothing

            c)        action3

                                    i.              name:                 P1action

                                  ii.              precondition       nothing

                                iii.              effect:                  predicate

            2.      initial casual link set bookkeeping

            a)       empty set

            3.      initial action order set bookkeeping

            a)       start < finish

             

            Problem and discussion:

            1.      Problem:

            a)       Is it possible for you to delete the step 2) (start < s-add < finish)?

            2.      discussion:

            a)       Not correct.

            b)       My reason:

                                    i.              Requirement of Linearization:

            1.        POP”’s full name is Parital-order Planner. It means if needs, it is sure that after linearizations of POP plan, “Total order plans” can be gained.

            2.        But if you delete the “step 2)”, the order relationship between start and “P1action” will not be written down in the “action order set bookkeeping”, it is difficult for the above linearizations operation.

            3.        In last 2nd paragraph of page 350 (AIMA version 1), light arrows in the figure show ordering constraints….., Also, all causes are constrained to come before their effects, so you can think of each bold arrow as having a light arrow underneath it.

                                  ii.              Requirement of procedure “RESOLVE-THREATS” and function “POP”

            1.        In the function “POP”, procedure “CHOOSE-OPERATOR” and “RESOLVE-THREATS” are closely linked, that’s, one by one. It means after adding “casual link” and “order link” in “CHOOSE-OPERATOR”, the procedure “RESOLVE-THREATS” will check the threat has been happened or not. If happens, It will try to solve it immediately. This immediately check needs the ordering information. And the solving of threat also needs the ordering information.

            2.        If the ordering information doesn’t exist, The “Resolve-threats” doesn’t work.

             

             

            I am also interested in the POP implementation for fully understanding and research later, but I want to use lisp language.

             

             

            Kind regards/chenyu

             

            -----Original Message-----
            From: yougooh2000 [mailto:hugo.ferreira@...]
            Sent: 2003年12月12日 17:18
            To: aima-talk@yahoogroups.com
            Subject: [aima-talk] Re: POP Planner Implementation: Choose-Operator

             

            Hi,

             

            First versions will (hopefully) be in Prolog. This is for research

            purposes.

             

            Regards,

            Hugo.

             

             

            --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...> wrote:

            > Hello,

            > Which language will you use for implementation?

            >

            > Best regards/chenyu

            >

            > -----Original Message-----

            > From: yougooh2000 [mailto:hugo.ferreira@m...]

            > Sent: 2003Äê12ÔÂ12ÈÕ 0:06

            > To: aima-talk@yahoogroups.com

            > Subject: [aima-talk] POP Planner Implementation: Choose-Operator

            >

            > Hi,

            >

            > I am attempting to implement the POP planner as is described in

            AIMA's

            > 1st version (Chap. 11.). I am having doubts regarding the call

            > "choose-operator" that is described in the book. The

            > pseudo-code says

            > that if the step to add (S-add) is selected from operator's list

            (not

            > the plan), then it is necessary to:

            > 1)Add this new step to the plans already existing steps.

            > 2)Add the ordering: Start < S-add < Finish

            >

            > I cannot understand what is the need for step 2). Say for example I

            > start the planner with a minimal plan of {Start, Finish} and on

            > selecting the first operator, I only find an S-add from the

            operator's

            > list. I will have to add the ordering S-add < S-need, where S-need =

            > Finish, according to the 5th pseudo-code line of the call. After

            that

            > I see that I have to execute steps 1 and 2 as described above. Now I

            > have a _repeated_ attempt to add ordering S-add < Finish.

            >

            > I have considered not doing step 2) which would result in a missing

            > ordering Start < S-add. I figure this will eventually be added to

            the

            > orderings when I process step S-add (i.e: attempt to satisfy its

            > pre-conditions).

            >

            > Am I missing something?

            >

            > TIA.

            > Hugo Ferreira.

            >

            >

            >

            > To unsubscribe from this group, send an email to:

            > aima-talk-unsubscribe@yahoogroups.com

            >

            > 

            >

            > Your use of Yahoo! Groups is subject to

            http://docs.yahoo.com/info/terms/

             

             

            ------------------------ Yahoo! Groups Sponsor ---------------------~-->

            Buy Ink Cartridges or Refill Kits for your HP, Epson, Canon or Lexmark

            Printer at MyInks.com. Free s/h on orders $50 or more to the US & Canada.

            http://www.c1tracking.com/l.asp?cid=5511

            http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/7brrlB/TM

            ---------------------------------------------------------------------~->

             

            To unsubscribe from this group, send an email to:

            aima-talk-unsubscribe@yahoogroups.com

             

             

             

            Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

             

          • yougooh2000
            Hi Chenyu, Thanks for the feedback. Unfortunatelly I could not understand much of your example. I cannot read the characters 8-(. As far as linearization goes,
            Message 5 of 7 , Dec 18, 2003
              Hi Chenyu,

              Thanks for the feedback. Unfortunatelly I could not understand much of
              your example. I cannot read the characters 8-(. As far as
              linearization goes, you are correct: to check and handle threats I
              need to have the correct orderings. My initial implementation (which
              is still not working), does insert the S-add < Finish because it
              regards Start as a standard step in the plan when selecting a
              sub-goal. As far as Start < S-add I have to check on that and see how
              it influences threat detection and resolution. Nevertheless because I
              also handle Finish as a step I do get a Start < S-add, but not in the
              same point in time.

              Regards,
              Hugo F.



              --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...> wrote:
              > Hello,
              > I have read the pecudo code again give you my thinking here. If you
              delete the step 2) (start < s-add < finish), the following problem
              will happens, To make the discussion more clearly, I give the context
              (To simplify the problem, I will ignore the variables):
              > Context:
              > 1. actions
              > a) action1
              > i. name: start
              > ii. precondition: nothing
              > iii. effect:
              nothing
              > b) action2
              > i. name: finish
              > ii. precondition: predicate
              > iii. effect:
              nothing
              > c) action3
              > i. name:
              P1action
              > ii. precondition nothing
              > iii. effect:
              predicate
              > 2. initial casual link set bookkeeping
              > a) empty set
              > 3. initial action order set bookkeeping
              > a) start < finish
              >
              > Problem and discussion:
              > 1. Problem:
              > a) Is it possible for you to delete the step 2) (start < s-add
              < finish)?
              > 2. discussion:
              > a) Not correct.
              > b) My reason:
              > i. Requirement of
              Linearization:
              > 1. €  â' '¼POP€  â' '½â' '¹s full name is Parital-order
              Planner. It means
              if needs, it is sure that after linearizations of POP plan,
              €  â' '¼Total
              order plans€  â' '½ can be gained.
              > 2. But if you delete the €  â' '¼step 2)€  â' '½, the order
              relationship between start and €  â' '¼P1action€  â' '½ will not be
              written down
              in the €  â' '¼action order set bookkeeping€  â' '½, it is difficult
              for the
              above linearizations operation.
              > 3. In last 2nd paragraph of page 350 (AIMA version 1), light
              arrows in the figure show ordering constraints€  â' ¦.., Also, all
              causes
              are constrained to come before their effects, so you can think of each
              bold arrow as having a light arrow underneath it.
              > ii. Requirement of procedure
              €  â' '¼RESOLVE-THREATS€  â' '½ and function €  â' '¼POP€  â' '½
              > 1. In the function €  â' '¼POP€  â' '½, procedure
              €  â' '¼CHOOSE-OPERATOR€  â' '½
              and €  â' '¼RESOLVE-THREATS€  â' '½ are closely linked,
              that€  â' '¹s, one by one. It
              means after adding €  â' '¼casual link€  â' '½ and €  â' '¼order
              link€  â' '½ in
              €  â' '¼CHOOSE-OPERATOR€  â' '½, the procedure €  
              â' '¼RESOLVE-THREATS€  â' '½ will check
              the threat has been happened or not. If happens, It will try to solve
              it immediately. This immediately check needs the ordering information.
              And the solving of threat also needs the ordering information.
              > 2. If the ordering information doesn€  â' '¹t exist, The
              €  â' '¼Resolve-threats€  â' '½ doesn€  â' '¹t work.
              >
              >
              > I am also interested in the POP implementation for fully
              understanding and research later, but I want to use lisp language.
              >
              >
              > Kind regards/chenyu
              >
              > -----Original Message-----
              > From: yougooh2000 [mailto:hugo.ferreira@m...]
              > Sent: 2003€  å¹´12€  æ'¼'¨12€  æ'·¥ 17:18
              > To: aima-talk@yahoogroups.com
              > Subject: [aima-talk] Re: POP Planner Implementation: Choose-Operator
              >
              > Hi,
              >
              > First versions will (hopefully) be in Prolog. This is for research
              > purposes.
              >
              > Regards,
              > Hugo.
              >
              >
              > --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...> wrote:
              > > Hello,
              > > Which language will you use for implementation?
              > >
              > > Best regards/chenyu
              > >
              > > -----Original Message-----
              > > From: yougooh2000 [mailto:hugo.ferreira@m...]
              > > Sent: 2003€  Ã'¤Ãª12€  Ã'´Ã'¢12€  Ã'¨Ã'µ 0:06
              > > To: aima-talk@yahoogroups.com
              > > Subject: [aima-talk] POP Planner Implementation: Choose-Operator
              > >
              > > Hi,
              > >
              > > I am attempting to implement the POP planner as is described in
              > AIMA's
              > > 1st version (Chap. 11.). I am having doubts regarding the call
              > > "choose-operator" that is described in the book. The
              > > pseudo-code says
              > > that if the step to add (S-add) is selected from operator's list
              > (not
              > > the plan), then it is necessary to:
              > > 1)Add this new step to the plans already existing steps.
              > > 2)Add the ordering: Start < S-add < Finish
              > >
              > > I cannot understand what is the need for step 2). Say for example
              I
              > > start the planner with a minimal plan of {Start, Finish} and on
              > > selecting the first operator, I only find an S-add from the
              > operator's
              > > list. I will have to add the ordering S-add < S-need, where
              S-need =
              > > Finish, according to the 5th pseudo-code line of the call. After
              > that
              > > I see that I have to execute steps 1 and 2 as described above.
              Now I
              > > have a _repeated_ attempt to add ordering S-add < Finish.
              > >
              > > I have considered not doing step 2) which would result in a
              missing
              > > ordering Start < S-add. I figure this will eventually be added to
              > the
              > > orderings when I process step S-add (i.e: attempt to satisfy its
              > > pre-conditions).
              > >
              > > Am I missing something?
              > >
              > > TIA.
              > > Hugo Ferreira.
              > >
              > >
              > >
              > > To unsubscribe from this group, send an email to:
              > > aima-talk-unsubscribe@yahoogroups.com
              > >
              > >
              > >
              > > Your use of Yahoo! Groups is subject to
              > http://docs.yahoo.com/info/terms/
              >
              >
              >
              > To unsubscribe from this group, send an email to:
              > aima-talk-unsubscribe@yahoogroups.com
              >
              >
              >
              > Your use of Yahoo! Groups is subject to
              http://docs.yahoo.com/info/terms/
            • chenyu468
              Hello Hugo, I have use notepad to format the reply and eliminate the special characters. I hope it is readable now. In addition, for your program s problem
              Message 6 of 7 , Dec 18, 2003
                Hello Hugo,
                I have use "notepad" to format the reply and eliminate the special
                characters. I hope it is readable now.

                In addition, for your program's problem (don't work), maybe firstly
                test the simplest planning problem as follows (context) to find the
                error, then comparing with the pceudo-code to find the problem. I
                haven't start this implementation now.


                kind regards/chenyu




                ;;;;;;;;;;;;;;;;;
                ;;last message
                ;;;;;;;;;;;;;;;;;
                I have read the pecudo code again give you my thinking here. If you
                delete the step 2) (start < s-add < finish), the following problem
                will happens, To make the discussion more clearly, I give the context
                (To simplify the problem, I will ignore the variables):

                Context:

                1. actions
                a) action1
                i. name: start
                ii. precondition: nothing
                iii. effect: nothing
                b) action2
                i. name: finish
                ii. precondition: predicate
                iii. effect: nothing
                c) action3
                i. name: P1action
                ii. precondition nothing
                iii. effect: predicate
                2. initial casual link set bookkeeping
                a) empty set
                3. initial action order set bookkeeping
                a) start < finish

                Problem and discussion:
                1. Problem:
                a) Is it possible for you to delete the step 2)
                (start < s-add < finish)?
                2. discussion:
                a) Not correct.
                b) My reason:
                i. Requirement of Linearization:
                1. "POP"'s full name is Parital-
                order Planner. It means if needs, it is sure that after
                linearizations of POP plan, "Total order plans" can be gained.
                2. But if you delete the "step
                2)", the order relationship between start and "P1action" will not be
                written down in the "action order set bookkeeping", it is difficult
                for the above linearizations operation.
                3. In last 2nd paragraph of page
                350 (AIMA version 1), light arrows in the figure show ordering
                constraints¡­.., Also, all causes are constrained to come before
                their effects, so you can think of each bold arrow as having a light
                arrow underneath it.
                ii. Requirement of procedure "RESOLVE-
                THREATS" and function "POP"
                1. In the function "POP",
                procedure "CHOOSE-OPERATOR" and "RESOLVE-THREATS" are closely linked,
                that¡¯s, one by one. It means after adding "casual link" and "order
                link" in "CHOOSE-OPERATOR", the procedure "RESOLVE-THREATS" will
                check the threat has been happened or not. If happens, It will try to
                solve it immediately. This immediately check needs the ordering
                information. And the solving of threat also needs the ordering
                information.
                2. If the ordering information
                doesn¡¯t exist, The "Resolve-threats" doesn¡¯t work.


                I am also interested in the POP implementation for fully
                understanding and research later, but I want to use lisp language.


                Kind regards/chenyu



                --- In aima-talk@yahoogroups.com, "yougooh2000" <hugo.ferreira@m...>
                wrote:
                > Hi Chenyu,
                >
                > Thanks for the feedback. Unfortunatelly I could not understand much
                of
                > your example. I cannot read the characters 8-(. As far as
                > linearization goes, you are correct: to check and handle threats I
                > need to have the correct orderings. My initial implementation (which
                > is still not working), does insert the S-add < Finish because it
                > regards Start as a standard step in the plan when selecting a
                > sub-goal. As far as Start < S-add I have to check on that and see
                how
                > it influences threat detection and resolution. Nevertheless because
                I
                > also handle Finish as a step I do get a Start < S-add, but not in
                the
                > same point in time.
                >
                > Regards,
                > Hugo F.
                >
                >
                >
                > --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...> wrote:
                > > Hello,
                > > I have read the pecudo code again give you my thinking here. If
                you
                > delete the step 2) (start < s-add < finish), the following problem
                > will happens, To make the discussion more clearly, I give the
                context
                > (To simplify the problem, I will ignore the variables):
                > > Context:
                > > 1. actions
                > > a) action1
                > > i. name:
                start
                > > ii. precondition: nothing
                > > iii. effect:
                > nothing
                > > b) action2
                > > i. name:
                finish
                > > ii. precondition:
                predicate
                > > iii. effect:
                > nothing
                > > c) action3
                > > i. name:
                > P1action
                > > ii. precondition nothing
                > > iii. effect:
                > predicate
                > > 2. initial casual link set bookkeeping
                > > a) empty set
                > > 3. initial action order set bookkeeping
                > > a) start < finish
                > >
                > > Problem and discussion:
                > > 1. Problem:
                > > a) Is it possible for you to delete the step 2) (start < s-
                add
                > < finish)?
                > > 2. discussion:
                > > a) Not correct.
                > > b) My reason:
                > > i. Requirement of
                > Linearization:
                > > 1. €  ??¼POP€  ??½â'?¹s full name is Parital-order
                > Planner. It means
                > if needs, it is sure that after linearizations of POP plan,
                > €  ??¼Total
                > order plans€  ???can be gained.
                > > 2. But if you delete the €  ??¼step 2)€  ??? the order
                > relationship between start and €  ??¼P1action€  ???will not be
                > written down
                > in the €  ??¼action order set bookkeeping€  ??? it is difficult
                > for the
                > above linearizations operation.
                > > 3. In last 2nd paragraph of page 350 (AIMA version 1),
                light
                > arrows in the figure show ordering constraints€  ? ¦.., Also, all
                > causes
                > are constrained to come before their effects, so you can think of
                each
                > bold arrow as having a light arrow underneath it.
                > > ii. Requirement of procedure
                > €  ??¼RESOLVE-THREATS€  ???and function €  ??¼POP€  ???> >
                1. In the function €  ??¼POP€  ??? procedure
                > €  ??¼CHOOSE-OPERATOR€  ???> and €  ??¼RESOLVE-THREATS€  ???are
                closely linked,
                > that€  ??¹s, one by one. It
                > means after adding €  ??¼casual link€  ???and €  ??¼order
                > link€  ???in
                > €  ??¼CHOOSE-OPERATOR€  ??? the procedure €  
                > ??¼RESOLVE-THREATS€  ???will check
                > the threat has been happened or not. If happens, It will try to
                solve
                > it immediately. This immediately check needs the ordering
                information.
                > And the solving of threat also needs the ordering information.
                > > 2. If the ordering information doesn€  ??¹t exist, The
                > €  ??¼Resolve-threats€  ???doesn€  ??¹t work.
                > >
                > >
                > > I am also interested in the POP implementation for fully
                > understanding and research later, but I want to use lisp language.
                > >
                > >
                > > Kind regards/chenyu
                > >
                > > -----Original Message-----
                > > From: yougooh2000 [mailto:hugo.ferreira@m...]
                > > Sent: 2003€  å¹?2€  ???2€  ?·¥ 17:18
                > > To: aima-talk@yahoogroups.com
                > > Subject: [aima-talk] Re: POP Planner Implementation: Choose-
                Operator
                > >
                > > Hi,
                > >
                > > First versions will (hopefully) be in Prolog. This is for research
                > > purposes.
                > >
                > > Regards,
                > > Hugo.
                > >
                > >
                > > --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...>
                wrote:
                > > > Hello,
                > > > Which language will you use for implementation?
                > > >
                > > > Best regards/chenyu
                > > >
                > > > -----Original Message-----
                > > > From: yougooh2000 [mailto:hugo.ferreira@m...]
                > > > Sent: 2003€  ?¤Ã?2€  ?´Ã'?2€  ?¨Ã'?0:06
                > > > To: aima-talk@yahoogroups.com
                > > > Subject: [aima-talk] POP Planner Implementation: Choose-Operator
                > > >
                > > > Hi,
                > > >
                > > > I am attempting to implement the POP planner as is described in
                > > AIMA's
                > > > 1st version (Chap. 11.). I am having doubts regarding the call
                > > > "choose-operator" that is described in the book. The
                > > > pseudo-code says
                > > > that if the step to add (S-add) is selected from operator's list
                > > (not
                > > > the plan), then it is necessary to:
                > > > 1)Add this new step to the plans already existing steps.
                > > > 2)Add the ordering: Start < S-add < Finish
                > > >
                > > > I cannot understand what is the need for step 2). Say for
                example
                > I
                > > > start the planner with a minimal plan of {Start, Finish} and on
                > > > selecting the first operator, I only find an S-add from the
                > > operator's
                > > > list. I will have to add the ordering S-add < S-need, where
                > S-need =
                > > > Finish, according to the 5th pseudo-code line of the call. After
                > > that
                > > > I see that I have to execute steps 1 and 2 as described above.
                > Now I
                > > > have a _repeated_ attempt to add ordering S-add < Finish.
                > > >
                > > > I have considered not doing step 2) which would result in a
                > missing
                > > > ordering Start < S-add. I figure this will eventually be added
                to
                > > the
                > > > orderings when I process step S-add (i.e: attempt to satisfy its
                > > > pre-conditions).
                > > >
                > > > Am I missing something?
                > > >
                > > > TIA.
                > > > Hugo Ferreira.
                > > >
                > > >
                > > >
                > > > To unsubscribe from this group, send an email to:
                > > > aima-talk-unsubscribe@yahoogroups.com
                > > >
                > > >
                > > >
                > > > Your use of Yahoo! Groups is subject to
                > > http://docs.yahoo.com/info/terms/
                > >
                > >
                > >
                > > To unsubscribe from this group, send an email to:
                > > aima-talk-unsubscribe@yahoogroups.com
                > >
                > >
                > >
                > > Your use of Yahoo! Groups is subject to
                > http://docs.yahoo.com/info/terms/
              • yougooh2000
                Chenyu, Thanks for the feedback. As far as the problem is concerned, my tests until now show that I do not need to add the Start
                Message 7 of 7 , Dec 22, 2003
                  Chenyu,

                  Thanks for the feedback.

                  As far as the problem is concerned, my tests until now show that I do
                  not need to add the Start < S-add ordering. I need to test additional
                  worlds, but my initial ideia seems to be valid. I don't know if this
                  is due to the way in which I implemented the algorithm or some "bug".

                  Anyway here is the explanation: because the alg. is goal recursive I
                  only check for preconditions before I regress. If after an
                  operation/step has been selected I do not add Start < S-add, it does
                  not matter because I only check for the steps/operators that I have
                  selected until now with open preconditions. Start will therefore never
                  be considered, it has no pre-conds.

                  What about checking for consistency? This doesn't matter either
                  because I cannot promote anything before Start, nor for that matter
                  demote it after Finish. In other words consistency only checks for
                  steps consistency between Start and Finish (exclusive).

                  What about identifying threats? Just as in the case checking for
                  consistency, threats may only occur for operators/steps between Start
                  and Finish. So once again, if I do add a Start < S-add, I don't need
                  the info to identify threats.
                  Please note that the book's algo. just checks if an operator/step
                  "clobbers" anothers pre-conds. This means that after ordering, the
                  check for threats will still show the threats. I only use ordering
                  information so as not to repeatedly (and unecessarily) resolve
                  conflicts.

                  I hope this explanation is valid. In case I do detect a mistake, I
                  will post additional information.

                  Thanks again.
                  Regards,
                  Hugo.




                  --- In aima-talk@yahoogroups.com, "chenyu468" <chenyu468@y...> wrote:
                  > Hello Hugo,
                  > I have use "notepad" to format the reply and eliminate the special
                  > characters. I hope it is readable now.
                  >
                  > In addition, for your program's problem (don't work), maybe firstly
                  > test the simplest planning problem as follows (context) to find the
                  > error, then comparing with the pceudo-code to find the problem. I
                  > haven't start this implementation now.
                  >
                  >
                  > kind regards/chenyu
                  >
                  >
                  >
                  >
                  > ;;;;;;;;;;;;;;;;;
                  > ;;last message
                  > ;;;;;;;;;;;;;;;;;
                  > I have read the pecudo code again give you my thinking here. If you
                  > delete the step 2) (start < s-add < finish), the following problem
                  > will happens, To make the discussion more clearly, I give the
                  context
                  > (To simplify the problem, I will ignore the variables):
                  >
                  > Context:
                  >
                  > 1. actions
                  > a) action1
                  > i. name: start
                  > ii. precondition: nothing
                  > iii. effect: nothing
                  > b) action2
                  > i. name: finish
                  > ii. precondition: predicate
                  > iii. effect: nothing
                  > c) action3
                  > i. name: P1action
                  > ii. precondition nothing
                  > iii. effect: predicate
                  > 2. initial casual link set bookkeeping
                  > a) empty set
                  > 3. initial action order set bookkeeping
                  > a) start < finish
                  >
                  > Problem and discussion:
                  > 1. Problem:
                  > a) Is it possible for you to delete the step 2)
                  > (start < s-add < finish)?
                  > 2. discussion:
                  > a) Not correct.
                  > b) My reason:
                  > i. Requirement of Linearization:
                  > 1. "POP"'s full name is Parital-
                  > order Planner. It means if needs, it is sure that after
                  > linearizations of POP plan, "Total order plans" can be gained.
                  > 2. But if you delete the "step
                  > 2)", the order relationship between start and "P1action" will not
                  be
                  > written down in the "action order set bookkeeping", it is difficult
                  > for the above linearizations operation.
                  > 3. In last 2nd paragraph of page
                  > 350 (AIMA version 1), light arrows in the figure show ordering
                  > constraints¡­.., Also, all causes are constrained to come before
                  > their effects, so you can think of each bold arrow as having a
                  light
                  > arrow underneath it.
                  > ii. Requirement of procedure "RESOLVE-
                  > THREATS" and function "POP"
                  > 1. In the function "POP",
                  > procedure "CHOOSE-OPERATOR" and "RESOLVE-THREATS" are closely
                  linked,
                  > that¡¯s, one by one. It means after adding "casual link" and
                  "order
                  > link" in "CHOOSE-OPERATOR", the procedure "RESOLVE-THREATS" will
                  > check the threat has been happened or not. If happens, It will try
                  to
                  > solve it immediately. This immediately check needs the ordering
                  > information. And the solving of threat also needs the ordering
                  > information.
                  > 2. If the ordering information
                  > doesn¡¯t exist, The "Resolve-threats" doesn¡¯t work.
                  >
                  >
                  > I am also interested in the POP implementation for fully
                  > understanding and research later, but I want to use lisp language.
                  >
                  >
                  > Kind regards/chenyu
                  >
                  >
                  >
                  > --- In aima-talk@yahoogroups.com, "yougooh2000"
                  <hugo.ferreira@m...>
                  > wrote:
                  > > Hi Chenyu,
                  > >
                  > > Thanks for the feedback. Unfortunatelly I could not understand
                  much
                  > of
                  > > your example. I cannot read the characters 8-(. As far as
                  > > linearization goes, you are correct: to check and handle threats I
                  > > need to have the correct orderings. My initial implementation
                  (which
                  > > is still not working), does insert the S-add < Finish because it
                  > > regards Start as a standard step in the plan when selecting a
                  > > sub-goal. As far as Start < S-add I have to check on that and see
                  > how
                  > > it influences threat detection and resolution. Nevertheless
                  because
                  > I
                  > > also handle Finish as a step I do get a Start < S-add, but not in
                  > the
                  > > same point in time.
                  > >
                  > > Regards,
                  > > Hugo F.
                  > >
                  > >
                  > >
                  > > --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...>
                  wrote:
                  > > > Hello,
                  > > > I have read the pecudo code again give you my thinking here. If
                  > you
                  > > delete the step 2) (start < s-add < finish), the following problem
                  > > will happens, To make the discussion more clearly, I give the
                  > context
                  > > (To simplify the problem, I will ignore the variables):
                  > > > Context:
                  > > > 1. actions
                  > > > a) action1
                  > > > i. name:
                  > start
                  > > > ii. precondition:
                  nothing
                  > > > iii. effect:
                  > > nothing
                  > > > b) action2
                  > > > i. name:
                  > finish
                  > > > ii. precondition:
                  > predicate
                  > > > iii. effect:
                  > > nothing
                  > > > c) action3
                  > > > i. name:
                  > > P1action
                  > > > ii. precondition
                  nothing
                  > > > iii. effect:
                  > > predicate
                  > > > 2. initial casual link set bookkeeping
                  > > > a) empty set
                  > > > 3. initial action order set bookkeeping
                  > > > a) start < finish
                  > > >
                  > > > Problem and discussion:
                  > > > 1. Problem:
                  > > > a) Is it possible for you to delete the step 2) (start <
                  s-
                  > add
                  > > < finish)?
                  > > > 2. discussion:
                  > > > a) Not correct.
                  > > > b) My reason:
                  > > > i. Requirement of
                  > > Linearization:
                  > > > 1. € ??¼POP€ ??½â'?¹s full name is
                  Parital-order
                  > > Planner. It means
                  > > if needs, it is sure that after linearizations of POP plan,
                  > > € ??¼Total
                  > > order plans€ ???can be gained.
                  > > > 2. But if you delete the € ??¼step 2)€ ???
                  the order
                  > > relationship between start and € ??¼P1action€
                  ???will not be
                  > > written down
                  > > in the € ??¼action order set bookkeeping€ ??? it is
                  difficult
                  > > for the
                  > > above linearizations operation.
                  > > > 3. In last 2nd paragraph of page 350 (AIMA version 1),
                  > light
                  > > arrows in the figure show ordering constraints€ ? ¦..,
                  Also, all
                  > > causes
                  > > are constrained to come before their effects, so you can think of
                  > each
                  > > bold arrow as having a light arrow underneath it.
                  > > > ii. Requirement of procedure
                  > > € ??¼RESOLVE-THREATS€ ???and function €
                  ??¼POP€ ???> >
                  > 1. In the function € ??¼POP€ ??? procedure
                  > > € ??¼CHOOSE-OPERATOR€ ???> and €
                  ??¼RESOLVE-THREATS€ ???are
                  > closely linked,
                  > > that€ ??¹s, one by one. It
                  > > means after adding € ??¼casual link€ ???and €
                  ??¼order
                  > > link€ ???in
                  > > € ??¼CHOOSE-OPERATOR€ ??? the procedure €
                  > > ??¼RESOLVE-THREATS€ ???will check
                  > > the threat has been happened or not. If happens, It will try to
                  > solve
                  > > it immediately. This immediately check needs the ordering
                  > information.
                  > > And the solving of threat also needs the ordering information.
                  > > > 2. If the ordering information doesn€ ??¹t
                  exist, The
                  > > € ??¼Resolve-threats€ ???doesn€ ??¹t work.
                  > > >
                  > > >
                  > > > I am also interested in the POP implementation for fully
                  > > understanding and research later, but I want to use lisp language.
                  > > >
                  > > >
                  > > > Kind regards/chenyu
                  > > >
                  > > > -----Original Message-----
                  > > > From: yougooh2000 [mailto:hugo.ferreira@m...]
                  > > > Sent: 2003€ å¹?2€ ???2€ ?·¥ 17:18
                  > > > To: aima-talk@yahoogroups.com
                  > > > Subject: [aima-talk] Re: POP Planner Implementation: Choose-
                  > Operator
                  > > >
                  > > > Hi,
                  > > >
                  > > > First versions will (hopefully) be in Prolog. This is for
                  research
                  > > > purposes.
                  > > >
                  > > > Regards,
                  > > > Hugo.
                  > > >
                  > > >
                  > > > --- In aima-talk@yahoogroups.com, E etech058 <etech058@o...>
                  > wrote:
                  > > > > Hello,
                  > > > > Which language will you use for implementation?
                  > > > >
                  > > > > Best regards/chenyu
                  > > > >
                  > > > > -----Original Message-----
                  > > > > From: yougooh2000 [mailto:hugo.ferreira@m...]
                  > > > > Sent: 2003€ ?¤Ã?2€ ?´Ã'?2€ ?¨Ã'?0:06
                  > > > > To: aima-talk@yahoogroups.com
                  > > > > Subject: [aima-talk] POP Planner Implementation:
                  Choose-Operator
                  > > > >
                  > > > > Hi,
                  > > > >
                  > > > > I am attempting to implement the POP planner as is described
                  in
                  > > > AIMA's
                  > > > > 1st version (Chap. 11.). I am having doubts regarding the call
                  > > > > "choose-operator" that is described in the book. The
                  > > > > pseudo-code says
                  > > > > that if the step to add (S-add) is selected from operator's
                  list
                  > > > (not
                  > > > > the plan), then it is necessary to:
                  > > > > 1)Add this new step to the plans already existing steps.
                  > > > > 2)Add the ordering: Start < S-add < Finish
                  > > > >
                  > > > > I cannot understand what is the need for step 2). Say for
                  > example
                  > > I
                  > > > > start the planner with a minimal plan of {Start, Finish} and
                  on
                  > > > > selecting the first operator, I only find an S-add from the
                  > > > operator's
                  > > > > list. I will have to add the ordering S-add < S-need, where
                  > > S-need =
                  > > > > Finish, according to the 5th pseudo-code line of the call.
                  After
                  > > > that
                  > > > > I see that I have to execute steps 1 and 2 as described above.
                  > > Now I
                  > > > > have a _repeated_ attempt to add ordering S-add < Finish.
                  > > > >
                  > > > > I have considered not doing step 2) which would result in a
                  > > missing
                  > > > > ordering Start < S-add. I figure this will eventually be
                  added
                  > to
                  > > > the
                  > > > > orderings when I process step S-add (i.e: attempt to satisfy
                  its
                  > > > > pre-conditions).
                  > > > >
                  > > > > Am I missing something?
                  > > > >
                  > > > > TIA.
                  > > > > Hugo Ferreira.
                  > > > >
                  > > > >
                  > > > >
                  > > > > To unsubscribe from this group, send an email to:
                  > > > > aima-talk-unsubscribe@yahoogroups.com
                  > > > >
                  > > > >
                  > > > >
                  > > > > Your use of Yahoo! Groups is subject to
                  > > > http://docs.yahoo.com/info/terms/
                  > > >
                  > > >
                  > > >
                  > > > To unsubscribe from this group, send an email to:
                  > > > aima-talk-unsubscribe@yahoogroups.com
                  > > >
                  > > >
                  > > >
                  > > > Your use of Yahoo! Groups is subject to
                  > > http://docs.yahoo.com/info/terms/
                Your message has been successfully submitted and would be delivered to recipients shortly.