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 2

^{nd}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-OperatorHi,

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

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- 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/ - 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,

of

>

> Thanks for the feedback. Unfortunatelly I could not understand much

> your example. I cannot read the characters 8-(. As far as

how

> 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

> 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.

you

>

> 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

> delete the step 2) (start < s-add < finish), the following problem

context

> will happens, To make the discussion more clearly, I give the

> (To simplify the problem, I will ignore the variables):

start

> > Context:

> > 1. actions

> > a) action1

> > i. name:

> > ii. precondition: nothing

finish

> > iii. effect:

> nothing

> > b) action2

> > i. name:

> > ii. precondition:

predicate

> > iii. effect:

add

> 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-

> < finish)?

light

> > 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),

> arrows in the figure show ordering constraints ? ¦.., Also, all

each

> causes

> are constrained to come before their effects, so you can think of

> bold arrow as having a light arrow underneath it.

1. In the function ??¼POP ??? procedure

> > ii. Requirement of procedure

> ??¼RESOLVE-THREATS ???and function ??¼POP ???> >

> ??¼CHOOSE-OPERATOR ???> and ??¼RESOLVE-THREATS ???are

closely linked,

> that ??¹s, one by one. It

solve

> 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

> it immediately. This immediately check needs the ordering

information.

> And the solving of threat also needs the ordering information.

Operator

> > 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-

> >

wrote:

> > Hi,

> >

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

> > purposes.

> >

> > Regards,

> > Hugo.

> >

> >

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

> > > Hello,

example

> > > 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

> I

to

> > > 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

> > 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/ - 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

> > > >

> > > >

> > > >

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

> > >

> > >

> > >

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

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> > >

> > >

> > >

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