Hi everybody,

I want to develop an intelligent agent with a small knowledge base.
But I am not able to find out how to start implementing that. What i
am finding in "aima" is the theoritical part of developing an
intelligent agent.

Can anybody give me some directions how to start developing an
intelligent agent(start implementing) and what are the tools available
and required to develop such an intelligent agent.

regards,
mohan_bg

--- In aima-talk@yahoogroups.com, "mohan_bg2003" <mohan_bg2003@y...>
wrote:
> [...]
> Can anybody give me some directions how to start developing an
> intelligent agent(start implementing) [...]

http://mind.sourceforge.net/aisteps.html tells how.

Hi everybody,

I want to develop an intelligent agent with a small knowledge base.
But I am not able to find out how to start implementing that. What i
am finding in "aima" is the theoritical part of developing an
intelligent agent.

Can anybody give me some directions how to start developing an
intelligent agent(start implementing) and what are the tools available
and required to develop such an intelligent agent.

regards,
mohan_bg

Hi everybody,

I want to develop an intelligent agent with a small knowledge base.
But I am not able to find out how to start implementing that. What i
am finding in "aima" is the theoritical part of developing an
intelligent agent.

Can anybody give me some directions how to start developing an
intelligent agent(start implementing) and what are the tools available
and required to develop such an intelligent agent.

regards,
mohan_bg

i m new to this group! can nebody pls help me with the solutions to the
exercises of chs 1 to 5 of 2nd edition!
its urgent!

Hi all,
Aima java 0.4 with additional code for probability and supervised
machine learning  (plus quite a few  bug fixes) has been posted on the
aima site .You will need java 1.5 to run the code .


The index file has not been updated yet so don't get freaked . The
additional chapters covered are 13, 14, 18 and 20 .In addition ,the
propositional logic code has been re written and should work much better.

Download ! enjoy!

Plans are afoot to make it easier to access/contribute to  the code
base  and file  bug reports and change requests . Till these changes
come into effect, please send any comments or  report any bugs
directly to me  .Please do not post java specific doubts etc on  this
group . I generally respond withing 12 hours of receiving mail .

Regards,
Ravi

Hi,

Thank you very much for:

AT Murray
Mohammad Assarian
Osamah alsaidi

all three of you for showing me some direction to go ahead with the
implementation. I will explore them and request help if needed.

Thank you very much indeed.

regards,
mohan_bg
--- In aima-talk@yahoogroups.com, Osamah alsaidi <ibnalsaidi@y...> wrote:
> First of all, "Knowledge base", this could be your database of
facts. If you are using prolog then u can start by building a small
set of facts in a simple file. Now intelligent agent ... well thats
the good thing about having a book. If you notice, agents differ in
characteristics. Now for example, some of them remember what they did
in previous state, some of them don't, some of them update their own
environment, some of them share the same environment with other
agents. Now, this all depends on what kind of intelligent agent u r
trying to build. Maybe also you want to build a learning agent. I
haven't read the book, but for a start and if it is your first
program, then you might investigate the theoritical concepts in the
book and for example, if the book says agents of type xx communicate
through a common knowledge base, then you encode this in your program
(but following a formal definition, ex, FSM steps) code. Ex, in prolog
both agents can update the same environment using
>  assert  or retract (beware these two commands donot retract if
query fails). I never used java for this, but think perhaps two agents
update the same object (a separate object).
>
> Thats all I can think of at this moment, hope it helps.
>
> Good luck.
>
>
>
> mohan_bg2003 <mohan_bg2003@y...> wrote:
> Hi everybody,
>
> I want to develop an intelligent agent with a small knowledge base.
> But I am not able to find out how to start implementing that. What i
> am finding in "aima" is the theoritical part of developing an
> intelligent agent.
>
> Can anybody give me some directions how to start developing an
> intelligent agent(start implementing) and what are the tools available
> and required to develop such an intelligent agent.
>
> regards,
> mohan_bg
>
>
>
>
>
>
> ---------------------------------
> YAHOO! GROUPS LINKS
>
>
>     Visit your group "aima-talk" on the web.
>
>     To unsubscribe from this group, send an email to:
>  aima-talk-unsubscribe@yahoogroups.com
>
>     Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service.
>
>
> ---------------------------------

--- In aima-talk@yahoogroups.com,
"mohan_bg2003" <mohan_bg2003@y...> wrote:
> Hi,
>
> Thank you very much for:
>
> AT Murray
> Mohammad Assarian
> Osamah alsaidi
>
> all three of you for showing me some direction to go ahead with the
> implementation. I will explore them and request help if needed.
>
> Thank you very much indeed.
>
> regards,
> mohan_bg

You are very welcome.

By the way, today on 29 August 2005 I finally achieved True AI in

http://mind.sourceforge.net/mind4th.html -- Mind.Forth as in

http://doi.acm.org/10.1145/307824.307853 (1998 ACM) and

http://doi.acm.org/10.1145/1052883.1052885 (2004 ACM).

http://mind.sourceforge.net/theory5.html is the AI theory.

http://mind.sourceforge.net/m4thuser.html is the User Manual.

It has taken many years to solve AI in both theory and software.

Now all the AI textbooks ought to be rewritten about True AI.

I would welcome anyone showing that Mind.Forth does not think.

http://www.914pcbots.com has detailed info in the A.I. Zone.

Hello soulmates,
on chapter 7, figure 7.13, the PL-RESOLUTION algorithm is proposed with a
helper function, PL-RESOLVE, that returns the set of all possible
clauses obtained by resolving two inputs.
However, on the previous page the resolution rule is described removing
all complementary literals at one. And on the next page you can read that
"any clause in which two complementary literals appear can be discarded."

I wonder if PL-RESOLVE should just remove all complementary literals and
returns just a clause with the remaining literals.

Iván Villanueva
--
Encrypted mail preferred.
GPG Key Id: 3FDBF85F 2004-10-18 Ivan-Fernando Villanueva Barrio

On Mon, Sep 05, 2005 at 04:27:31PM +0200, Ivan Villanueva wrote:
> on chapter 7, figure 7.13, the PL-RESOLUTION algorithm is proposed with a
> helper function, PL-RESOLVE, that returns the set of all possible
> clauses obtained by resolving two inputs.
> However, on the previous page the resolution rule is described removing
> all complementary literals at one.

That is not the case. Sorry.

> I wonder if PL-RESOLVE should just remove all complementary literals and
> returns just a clause with the remaining literals.

Of course not. The resolution rule allows to discard two complementary literals,
but not more at one.
For example with the two sentences:

~P1,2 | ~P2,1 | B1,1    ~B1,1 | P1,2 | P2,1

one can apply the resolution rule and get:

~P1,2 | ~P2,1 | P1,2 | P2,1

but not an empty clause.


Ivan Villanueva :-)

HI

I am studying AI on my own and I need C/C++ codes for the pesudocodes
in the book,also is there any way to get the solutions for the
exercises of the book in my case? (I am no taking a course using AIMA)?

please if you can help me,let me know

thank you

Hello!
I've read the paragraph about AI becoming a science and therefore more
formal. But somehow I'm having the impression that the informal
approach to problems in AI remains to be more common rather than
the rigorous/proof based style of other fields in computer science.
Don't get me wrong - that isn't meant as a criticism of the book, just
a general impression. (I've encountered other AI books/papers that
afirmed this.)

So where about can AI be found (considering a "formality hierarchy")?
Close to Formal Methods and Analysis of Algorithms, or rather near
fields like Software Engineering?
Maybe someone with more experience than me could comment on this?

regards

__________________________________________________
Do You Yahoo!?
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Hi Bruce,

I think "this statement is definitely false" is more a paradox than a
contradiction, for when you decide it is false then it is true, and vice
versa. A contradiction is always false. And "consistently" has two
readings, one is the randomness you meant, and another reading common in
philosophical literature is that it is possible for a set of
propositions to all true. I'm just not sure which meaning the authors
seem to imply.

Paul

Tommy Gun wrote:

>     Sounds like sort of a contradiction.  The words "cannot
>     consistently" I think give it the flexability to sometimes be true
>     and sometimes not.  If the sentence was definate all of the time,
>     then it would just be a contradiction.   Take "this statement is
>     definately false" is a contradiction, but if it were, "this
>     statement is sometimes false" then there sometimes when it isn't a
>     contradiction.  "cannot  consistently" basically says that's it's
>     sorta random, so sometimes it could make sense.
>
>     Not sure if that helps, but it's just my $.02...
>
>      - Bruce
>
>
>     Message: 1
>     Date: Sun, 11 Sep 2005 23:08:35 +0800
>     From: Paul Hsueh-Min Chang
>     Subject: Problem about the J.R. Lucas sentence
>
>     Hi,
>
>     On page 950, the book argues that the sentence "J. R. Lucas cannot
>     consistently assert that this sentence is true." is necessarily true,
>     but Lucas cannot consistently assert it. There are two arguments
>     on that
>     page. I found no problem with the first argument, but could not
>     understand the second.
>
>     Here is the second argument.
>
>     "The sentence cannot be false, because if it were then Lucas could not
>     consistently assert it, so it would be true."
>
>     But, why couldn't Lucas consistently assert it /if it were false/? One
>     can of course assert a false sentence and be consistent at the same
>     time, because one is inconsistent if and only if it is
>     /impossible/ that
>     all his beliefs are true. If Lucas happens to believe a false
>     sentence,
>     he is still consistent.
>
>     Please help/correct me.
>
>     Paul
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
> ------------------------------------------------------------------------
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To try and understand this equation I assumed the following:
number of possible percepts P = 3
lifetime of the agent (number of percepts it will receive) = 3
I the get an answer for the summation of 39.  However, if I manually
determine the number of possible ways in which the percepts can be
received I get 15 for the size of the lookup table.  Can somebody tell
me what I am not undestanding correctly?

Fred Kindl
fredkindl@...

I believe if you look at the "setup" on the previous
page you'll see the authors intended the term
"consistent" to be the logical definition. (see pages
137 and 353)  That is, for something to be consistent,
it cannot be contradictory.  Therefore, if the
sentance were false, he couldn't assert the sentance
and still be consistent, which therefore makes the
sentance true.

But the point of the paragraph is that because of the
construction of the sentance, the agent "J.R. Lucas"
cannot assert something that other agents can.
However the authors are pointing out that this doesn't
make him inferior.

Rob G.

--- Paul Hsueh-Min Chang <avatar@...>
wrote:

> Hi Bruce,
>
> I think "this statement is definitely false" is more
> a paradox than a
> contradiction, for when you decide it is false then
> it is true, and vice
> versa. A contradiction is always false. And
> "consistently" has two
> readings, one is the randomness you meant, and
> another reading common in
> philosophical literature is that it is possible for
> a set of
> propositions to all true. I'm just not sure which
> meaning the authors
> seem to imply.
>
> Paul
>
> Tommy Gun wrote:
>
> >     Sounds like sort of a contradiction.  The
> words "cannot
> >     consistently" I think give it the flexability
> to sometimes be true
> >     and sometimes not.  If the sentence was
> definate all of the time,
> >     then it would just be a contradiction.   Take
> "this statement is
> >     definately false" is a contradiction, but if
> it were, "this
> >     statement is sometimes false" then there
> sometimes when it isn't a
> >     contradiction.  "cannot  consistently"
> basically says that's it's
> >     sorta random, so sometimes it could make
> sense.
> >
> >     Not sure if that helps, but it's just my
> $.02...
> >
> >      - Bruce
> >
> >
> >     Message: 1
> >     Date: Sun, 11 Sep 2005 23:08:35 +0800
> >     From: Paul Hsueh-Min Chang
> >     Subject: Problem about the J.R. Lucas sentence
> >
> >     Hi,
> >
> >     On page 950, the book argues that the sentence
> "J. R. Lucas cannot
> >     consistently assert that this sentence is
> true." is necessarily true,
> >     but Lucas cannot consistently assert it. There
> are two arguments
> >     on that
> >     page. I found no problem with the first
> argument, but could not
> >     understand the second.
> >
> >     Here is the second argument.
> >
> >     "The sentence cannot be false, because if it
> were then Lucas could not
> >     consistently assert it, so it would be true."
> >
> >     But, why couldn't Lucas consistently assert it
> /if it were false/? One
> >     can of course assert a false sentence and be
> consistent at the same
> >     time, because one is inconsistent if and only
> if it is
> >     /impossible/ that
> >     all his beliefs are true. If Lucas happens to
> believe a false
> >     sentence,
> >     he is still consistent.
> >
> >     Please help/correct me.
> >
> >     Paul
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam
> protection around
> > http://mail.yahoo.com
> >
> >
>
------------------------------------------------------------------------
> > YAHOO! GROUPS LINKS
> >
> >     *  Visit your group "aima-talk
> >       <http://groups.yahoo.com/group/aima-talk>"
> on the web.
> >
> >     *  To unsubscribe from this group, send an
> email to:
> >        aima-talk-unsubscribe@yahoogroups.com
> >
>
<mailto:aima-talk-unsubscribe@yahoogroups.com?subject=Unsubscribe>
> >
> >     *  Your use of Yahoo! Groups is subject to the
> Yahoo! Terms of
> >       Service <http://docs.yahoo.com/info/terms/>.
> >
> >
> >
>
------------------------------------------------------------------------
> >
>
>
>
>




__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com

I'm not sure if you're being consistent in your
definition of P, the possible precepts, since I can't
figure out how you arrived at 15.  (I agree with 39).

To make life easy, assume you have a single sensor
which can return one of three values - A, B, or C.
The possible precept combinations can therefore be
enumerated as:

A
B
C
AA
AB
AC
BA
BB
BC
...
AAA
AAB
AAC
ABA
...

I think you'll find (as the formula implies) there are
3 possible combinations after the first input is
received (t=1), there are 3^3 = 9 additonal
combinations when the second input is received (t=2),
and 3^3^3 additional combinations once the 3rd input
is received (t=3).  Add them all together, and you can
see the agent would need a total of 39 table entries
to know what action to take based on it's precept
history.

Rob G.

--- kindlencotech <fredkindl@...> wrote:

> To try and understand this equation I assumed the
> following:
> number of possible percepts P = 3
> lifetime of the agent (number of percepts it will
> receive) = 3
> I the get an answer for the summation of 39.
> However, if I manually
> determine the number of possible ways in which the
> percepts can be
> received I get 15 for the size of the lookup table.
> Can somebody tell
> me what I am not undestanding correctly?
>
> Fred Kindl
> fredkindl@...
>
>
>
>
>
>


__________________________________________________
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Tired of spam?  Yahoo! Mail has the best spam protection around
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But my question is that being false does *not* equal being contradictory
(i.e. necessarily false).  If the sentence were merely false but not
contradictory, he surely could consistently assert it.

So lets review the argument:

"The sentence cannot be false, because if it were then Lucas could not
consistently assert it, so it would be true."

Consider two conditions:
1. If the sentence were meant to be merely false, then Lucas could
consistently assert it, so the argument is invalid.
2. If the sentence were meant to be contradictory, then nobody could
consistently assert it, but then the argument would have a very strange
form: "if p were contradictory then A could not assert it, so p would be
true." Consider the following argument of the same form: "If 'Saddam
Hussein is the US President' were contradictory, then I could not assert
it, so he would be the US President". Clearly absurd.

Again, please correct me if I am wrong.

Paul

The Geek wrote:

> I believe if you look at the "setup" on the previous
> page you'll see the authors intended the term
> "consistent" to be the logical definition. (see pages
> 137 and 353)  That is, for something to be consistent,
> it cannot be contradictory.  Therefore, if the
> sentance were false, he couldn't assert the sentance
> and still be consistent, which therefore makes the
> sentance true.
>
> But the point of the paragraph is that because of the
> construction of the sentance, the agent "J.R. Lucas"
> cannot assert something that other agents can.
> However the authors are pointing out that this doesn't
> make him inferior.
>
> Rob G.
>
> --- Paul Hsueh-Min Chang <avatar@...>
> wrote:
>
> > Hi Bruce,
> >
> > I think "this statement is definitely false" is more
> > a paradox than a
> > contradiction, for when you decide it is false then
> > it is true, and vice
> > versa. A contradiction is always false. And
> > "consistently" has two
> > readings, one is the randomness you meant, and
> > another reading common in
> > philosophical literature is that it is possible for
> > a set of
> > propositions to all true. I'm just not sure which
> > meaning the authors
> > seem to imply.
> >
> > Paul
> >
> > Tommy Gun wrote:
> >
> > >     Sounds like sort of a contradiction.  The
> > words "cannot
> > >     consistently" I think give it the flexability
> > to sometimes be true
> > >     and sometimes not.  If the sentence was
> > definate all of the time,
> > >     then it would just be a contradiction.   Take
> > "this statement is
> > >     definately false" is a contradiction, but if
> > it were, "this
> > >     statement is sometimes false" then there
> > sometimes when it isn't a
> > >     contradiction.  "cannot  consistently"
> > basically says that's it's
> > >     sorta random, so sometimes it could make
> > sense.
> > >
> > >     Not sure if that helps, but it's just my
> > $.02...
> > >
> > >      - Bruce
> > >
> > >
> > >     Message: 1
> > >     Date: Sun, 11 Sep 2005 23:08:35 +0800
> > >     From: Paul Hsueh-Min Chang
> > >     Subject: Problem about the J.R. Lucas sentence
> > >
> > >     Hi,
> > >
> > >     On page 950, the book argues that the sentence
> > "J. R. Lucas cannot
> > >     consistently assert that this sentence is
> > true." is necessarily true,
> > >     but Lucas cannot consistently assert it. There
> > are two arguments
> > >     on that
> > >     page. I found no problem with the first
> > argument, but could not
> > >     understand the second.
> > >
> > >     Here is the second argument.
> > >
> > >     "The sentence cannot be false, because if it
> > were then Lucas could not
> > >     consistently assert it, so it would be true."
> > >
> > >     But, why couldn't Lucas consistently assert it
> > /if it were false/? One
> > >     can of course assert a false sentence and be
> > consistent at the same
> > >     time, because one is inconsistent if and only
> > if it is
> > >     /impossible/ that
> > >     all his beliefs are true. If Lucas happens to
> > believe a false
> > >     sentence,
> > >     he is still consistent.
> > >
> > >     Please help/correct me.
> > >
> > >     Paul
> > >
>

Hi my name is mazhar & recently I join this group, coz I need
your/experts helps.
I m belonging from Pakistan & the student of MCS. Will u please tell me
the answer of exercise number 7.8 and 7.11 of AI A Modern Approach by
Russal.
Most important is Exercise 7.11 Minesweeper that will create more
problem from me so please any one of u solve this exercise & send it to
me, I m really thankful to u.
SYED ALI MAZHAR
MCS 2
FUAST University Karachi Pakistan
Mob: +92-333-2239246

I don't know if I'm explaining this very well.
Someone else should feel free to chime in if they've
got a better way of phrasing it...

While they haven't spelled it out in detail, I think
they're using a simple logic system and definition of
"consistent".  In other words, they're not trying to
allow for an "agent belief" representation where we
acknowledge that beliefs might be wrong.  Instead, if
you assert a sentance it must be true or you've
introduced a contradiction.

If we take 3 sentances:

A = B.
B = C.
A != C.

If we try to assert all three sentances, we cannot do
it without creating a contradiction.  Since this is
the definition of "consistency", they would say that
we cannot "consistently" assert all three sentances,
since doing so would introduce a contradiction.

The example is a little more complicated, since
they're violating a couple of normal rules for logic
systems - they have a sentance referring to the
assertability of sentances.  But if you reword the
sentance to say "Agent A cannot assert this sentance
without being wrong" I think it's a little more clear.

In this case, as an agent **I** can consistently
assert the sentance "Agent A cannot assert this
sentance without being wrong" without introducing a
contradiction.  However if Agent A tries to assert the
same sentance, he runs into a problem.  If he asserts
it as true and is right, then the sentance is false,
so he's wrong.

But the whole point of the illustration is simply to
show that **sometimes** one agent is unable to
assert/know/do things that another agent can, but that
doesn't automatically imply that agent is inferior,
it's inability to assert/know/do may be related to the
specific situation.

Rob G.

--- Paul Hsueh-Min Chang <avatar@...>
wrote:

> But my question is that being false does *not* equal
> being contradictory
> (i.e. necessarily false).  If the sentence were
> merely false but not
> contradictory, he surely could consistently assert
> it.
>
> So lets review the argument:
>
> "The sentence cannot be false, because if it were
> then Lucas could not
> consistently assert it, so it would be true."
>
> Consider two conditions:
> 1. If the sentence were meant to be merely false,
> then Lucas could
> consistently assert it, so the argument is invalid.
> 2. If the sentence were meant to be contradictory,
> then nobody could
> consistently assert it, but then the argument would
> have a very strange
> form: "if p were contradictory then A could not
> assert it, so p would be
> true." Consider the following argument of the same
> form: "If 'Saddam
> Hussein is the US President' were contradictory,
> then I could not assert
> it, so he would be the US President". Clearly
> absurd.
>
> Again, please correct me if I am wrong.
>
> Paul
>
> The Geek wrote:
>
> > I believe if you look at the "setup" on the
> previous
> > page you'll see the authors intended the term
> > "consistent" to be the logical definition. (see
> pages
> > 137 and 353)  That is, for something to be
> consistent,
> > it cannot be contradictory.  Therefore, if the
> > sentance were false, he couldn't assert the
> sentance
> > and still be consistent, which therefore makes the
> > sentance true.
> >
> > But the point of the paragraph is that because of
> the
> > construction of the sentance, the agent "J.R.
> Lucas"
> > cannot assert something that other agents can.
> > However the authors are pointing out that this
> doesn't
> > make him inferior.
> >
> > Rob G.
> >
> > --- Paul Hsueh-Min Chang
> <avatar@...>
> > wrote:
> >
> > > Hi Bruce,
> > >
> > > I think "this statement is definitely false" is
> more
> > > a paradox than a
> > > contradiction, for when you decide it is false
> then
> > > it is true, and vice
> > > versa. A contradiction is always false. And
> > > "consistently" has two
> > > readings, one is the randomness you meant, and
> > > another reading common in
> > > philosophical literature is that it is possible
> for
> > > a set of
> > > propositions to all true. I'm just not sure
> which
> > > meaning the authors
> > > seem to imply.
> > >
> > > Paul
> > >
> > > Tommy Gun wrote:
> > >
> > > >     Sounds like sort of a contradiction.  The
> > > words "cannot
> > > >     consistently" I think give it the
> flexability
> > > to sometimes be true
> > > >     and sometimes not.  If the sentence was
> > > definate all of the time,
> > > >     then it would just be a contradiction.
> Take
> > > "this statement is
> > > >     definately false" is a contradiction, but
> if
> > > it were, "this
> > > >     statement is sometimes false" then there
> > > sometimes when it isn't a
> > > >     contradiction.  "cannot  consistently"
> > > basically says that's it's
> > > >     sorta random, so sometimes it could make
> > > sense.
> > > >
> > > >     Not sure if that helps, but it's just my
> > > $.02...
> > > >
> > > >      - Bruce
> > > >
> > > >
> > > >     Message: 1
> > > >     Date: Sun, 11 Sep 2005 23:08:35 +0800
> > > >     From: Paul Hsueh-Min Chang
> > > >     Subject: Problem about the J.R. Lucas
> sentence
> > > >
> > > >     Hi,
> > > >
> > > >     On page 950, the book argues that the
> sentence
> > > "J. R. Lucas cannot
> > > >     consistently assert that this sentence is
> > > true." is necessarily true,
> > > >     but Lucas cannot consistently assert it.
> There
> > > are two arguments
> > > >     on that
> > > >     page. I found no problem with the first
> > > argument, but could not
> > > >     understand the second.
> > > >
> > > >     Here is the second argument.
> > > >
> > > >     "The sentence cannot be false, because if
> it
> > > were then Lucas could not
> > > >     consistently assert it, so it would be
> true."
> > > >
> > > >     But, why couldn't Lucas consistently
> assert it
> > > /if it were false/? One
> > > >     can of course assert a false sentence and
> be
> > > consistent at the same
> > > >     time, because one is inconsistent if and
> only
> > > if it is
> > > >     /impossible/ that
> > > >     all his beliefs are true. If Lucas happens
> to
> > > believe a false
> > > >     sentence,
> > > >     he is still consistent.
> > > >
> > > >     Please help/correct me.
> > > >
> > > >     Paul
> > > >
> >
>
>
>
>




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I will try to make some clarifications below:

> While they haven't spelled it out in detail, I think
> they're using a simple logic system and definition of
> "consistent".  In other words, they're not trying to
> allow for an "agent belief" representation where we
> acknowledge that beliefs might be wrong.  Instead, if
> you assert a sentance it must be true or you've
> introduced a contradiction.

Maybe our sources are different. AFAIK a contradiction is the negation
of a tautology (P. Tidman and H. Kahane, Logic and Philosophy: A Modern
Introduction, 8th edition, p48). For example, p^~p is a contradiction.
So when I assert a contingently false sentence whose truth depends on
the world, I introduce no contradiction. But maybe our definitions of
contradiction differ.

> If we take 3 sentances:
>
> A = B.
> B = C.
> A != C.
>
> If we try to assert all three sentances, we cannot do
> it without creating a contradiction.  Since this is
> the definition of "consistency", they would say that
> we cannot "consistently" assert all three sentances,
> since doing so would introduce a contradiction.

It is true that we would introduce inconsistency, but we would not
introduce a contradiction. Of course, any set of sentences that contains
any contradictory sentence is inconsistent, but not vice versa.

> In this case, as an agent **I** can consistently
> assert the sentance "Agent A cannot assert this
> sentance without being wrong" without introducing a
> contradiction.  However if Agent A tries to assert the
> same sentance, he runs into a problem.  If he asserts
> it as true and is right, then the sentance is false,
> so he's wrong.

I know what you are trying to say, but that I don't think we are talking
about the same thing. The authors clearly intend to show two things:
1. The sentence is a tautology (i.e. necessarily true).
2. Yet, J. R. Lucas cannot assert it.
They offer two arguments to show (1). What I do not understand is the
their second argument to show (1). You are talking about (2), which I
find no problem.

> But the whole point of the illustration is simply to
> show that **sometimes** one agent is unable to
> assert/know/do things that another agent can, but that
> doesn't automatically imply that agent is inferior,
> it's inability to assert/know/do may be related to the
> specific situation.

I do understand the point; it is simply that particular argument (the
one on p950 in parentheses) that confuses me. As a philosophical
treatment, I think the chapter should reasonably be taken literally, but
when I do so, I cannot make sense of that particular argument.

Paul

Hi,
   could anyone plz let me know the link to the answers of the
exercise
of this book

In page97, line 7:
The restriction is to choose an h function that never overestimates
the cost to reach the goal. Such an h is called an admissible
heuristic. Admissible heuristics are by nature optimistic, because
they think the cost of solving the problem is less than it actually is.

Can anyone give me more explanation why it always gets the optimial
result when it never overestimates the total cost.

In page97, line 7:
The restriction is to choose an h function that never overestimates
the cost to reach the goal. Such an h is called an admissible
heuristic. Admissible heuristics are by nature optimistic, because
they think the cost of solving the problem is less than it actually is.

Can anyone give me more explanation why it always gets the optimial
result when it never overestimates the total cost.

I think my version is different from yours, but I
assume you're talking about the A* search algorithm.

The proof is in the book a page or so later, but  look
at it the other way for a second - if the path
estimate were sometimes too high, then based on the
inflated estimate you might ignore a path that would
have turned out to have a "short cut" in it.  But by
guaranteeing that the actual cost will always be more
than your estimate, you're guaranteed never to ignore
a short cut.

To put it another way, with an admissible heuristic
any unexplored path is guaranteed to be worse than or
equal to it's estimate - never better.  Thus when you
actually explore a path, you're guaranteed that it's
cost will only get worse.  So if you've found an
actual path solution that's equal to or better than
the best unexplored path estimates, the actual path
you've found is guaranteed to be the best because the
unexplored paths can only get more costly when they're
explored.

I hope that made sense.

Rob G.

--- lwudong <wudongs@...> wrote:

> In page97, line 7:
> The restriction is to choose an h function that
> never overestimates
> the cost to reach the goal. Such an h is called an
> admissible
> heuristic. Admissible heuristics are by nature
> optimistic, because
> they think the cost of solving the problem is less
> than it actually is.
>
> Can anyone give me more explanation why it always
> gets the optimial
> result when it never overestimates the total cost.
>
>
>
>
>




__________________________________
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I think the discussion all boils down to the
definition of "consistent" and "contradiction".  I was
kind of hoping one of the authors would chime in at
some point to save me, but...  :-)  On page 137 they
define consistency in reference to CSP problems as "an
assignment that does not violate any constraints".
That was the reason for my A,B,C example - looking at
it as if it were a CSP.

Their argument assumes the sentance must either be
"true" or "false", (no quantuum physics or "unknown"
values allowed) and hinges on the
belief/assumption/fact one cannot "consistently"
assert that a sentance is true if it can be shown to
be false.  If you buy into that, then their statement
follows naturally - if the sentance was false, then he
could not consistently assert it to be true, which
would therefore make the sentance true - a
contradiction since we assigned a value of "false" to
the sentance at the beginning.  The only way you can
assign a value to the sentance and have everything
hold together is if you assume it's true, which then
implies that everyone else can assert it without a
problem, but he cannot.

But, at this point I don't think we're going to make
any headway.  Since they didn't define the logic
system they're using, we can't really do anything
formal.

Thanks for the interesting discussion.

Rob G.


--- Paul Hsueh-Min Chang <avatar@...>
wrote:

> I will try to make some clarifications below:
>
> > While they haven't spelled it out in detail, I
> think
> > they're using a simple logic system and definition
> of
> > "consistent".  In other words, they're not trying
> to
> > allow for an "agent belief" representation where
> we
> > acknowledge that beliefs might be wrong.  Instead,
> if
> > you assert a sentance it must be true or you've
> > introduced a contradiction.
>
> Maybe our sources are different. AFAIK a
> contradiction is the negation
> of a tautology (P. Tidman and H. Kahane, Logic and
> Philosophy: A Modern
> Introduction, 8th edition, p48). For example, p^~p
> is a contradiction.
> So when I assert a contingently false sentence whose
> truth depends on
> the world, I introduce no contradiction. But maybe
> our definitions of
> contradiction differ.
>
> > If we take 3 sentances:
> >
> > A = B.
> > B = C.
> > A != C.
> >
> > If we try to assert all three sentances, we cannot
> do
> > it without creating a contradiction.  Since this
> is
> > the definition of "consistency", they would say
> that
> > we cannot "consistently" assert all three
> sentances,
> > since doing so would introduce a contradiction.
>
> It is true that we would introduce inconsistency,
> but we would not
> introduce a contradiction. Of course, any set of
> sentences that contains
> any contradictory sentence is inconsistent, but not
> vice versa.
>
> > In this case, as an agent **I** can consistently
> > assert the sentance "Agent A cannot assert this
> > sentance without being wrong" without introducing
> a
> > contradiction.  However if Agent A tries to assert
> the
> > same sentance, he runs into a problem.  If he
> asserts
> > it as true and is right, then the sentance is
> false,
> > so he's wrong.
>
> I know what you are trying to say, but that I don't
> think we are talking
> about the same thing. The authors clearly intend to
> show two things:
> 1. The sentence is a tautology (i.e. necessarily
> true).
> 2. Yet, J. R. Lucas cannot assert it.
> They offer two arguments to show (1). What I do not
> understand is the
> their second argument to show (1). You are talking
> about (2), which I
> find no problem.
>
> > But the whole point of the illustration is simply
> to
> > show that **sometimes** one agent is unable to
> > assert/know/do things that another agent can, but
> that
> > doesn't automatically imply that agent is
> inferior,
> > it's inability to assert/know/do may be related to
> the
> > specific situation.
>
> I do understand the point; it is simply that
> particular argument (the
> one on p950 in parentheses) that confuses me. As a
> philosophical
> treatment, I think the chapter should reasonably be
> taken literally, but
> when I do so, I cannot make sense of that particular
> argument.
>
> Paul
>
>
>





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Yahoo! Mail - PC Magazine Editors' Choice 2005
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---

From: aima-talk@yahoogroups.com [mailto:aima-talk@yahoogroups.com] On Behalf Of The Geek
Sent: Monday, September 26, 2005 6:03 PM
To: aima-talk@yahoogroups.com
Subject: Re: [aima-talk] about A* search

I think my version is different from yours, but I
assume you're talking about the A* search algorithm.

The proof is in the book a page or so later, but  look
at it the other way for a second - if the path
estimate were sometimes too high, then based on the
inflated estimate you might ignore a path that would
have turned out to have a "short cut" in it.  But by
guaranteeing that the actual cost will always be more
than your estimate, you're guaranteed never to ignore
a short cut. 

To put it another way, with an admissible heuristic
any unexplored path is guaranteed to be worse than or
equal to it's estimate - never better.  Thus when you
actually explore a path, you're guaranteed that it's
cost will only get worse.  So if you've found an
actual path solution that's equal to or better than
the best unexplored path estimates, the actual path
you've found is guaranteed to be the best because the
unexplored paths can only get more costly when they're
explored.

I hope that made sense.

Rob G.

--- lwudong <wudongs@...> wrote:

> In page97, line 7:
> The restriction is to choose an h function that
> never overestimates
> the cost to reach the goal. Such an h is called an
> admissible
> heuristic. Admissible heuristics are by nature
> optimistic, because
> they think the cost of solving the problem is less
> than it actually is.
>
> Can anyone give me more explanation why it always
> gets the optimial
> result when it never overestimates the total cost.
>
>
>
>
>



           
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com

---

From: savastinuk [mailto:minnie@...]
Sent: Tuesday, September 27, 2005 7:04 AM
To: 'aima-talk@yahoogroups.com'
Subject: RE: [aima-talk] about A* search

This makes sense. : )

 

Can you also explain consistent? Or, better yet, INconsistent?

Still talking A*.

 

thanks....

Susan

---

From: aima-talk@yahoogroups.com [mailto:aima-talk@yahoogroups.com] On Behalf Of The Geek
Sent: Monday, September 26, 2005 6:03 PM
To: aima-talk@yahoogroups.com
Subject: Re: [aima-talk] about A* search

I think my version is different from yours, but I
assume you're talking about the A* search algorithm.

The proof is in the book a page or so later, but  look
at it the other way for a second - if the path
estimate were sometimes too high, then based on the
inflated estimate you might ignore a path that would
have turned out to have a "short cut" in it.  But by
guaranteeing that the actual cost will always be more
than your estimate, you're guaranteed never to ignore
a short cut. 

To put it another way, with an admissible heuristic
any unexplored path is guaranteed to be worse than or
equal to it's estimate - never better.  Thus when you
actually explore a path, you're guaranteed that it's
cost will only get worse.  So if you've found an
actual path solution that's equal to or better than
the best unexplored path estimates, the actual path
you've found is guaranteed to be the best because the
unexplored paths can only get more costly when they're
explored.

I hope that made sense.

Rob G.

--- lwudong <wudongs@...> wrote:

> In page97, line 7:
> The restriction is to choose an h function that
> never overestimates
> the cost to reach the goal. Such an h is called an
> admissible
> heuristic. Admissible heuristics are by nature
> optimistic, because
> they think the cost of solving the problem is less
> than it actually is.
>
> Can anyone give me more explanation why it always
> gets the optimial
> result when it never overestimates the total cost.
>
>
>
>
>



           
__________________________________
Yahoo! Mail - PC Magazine Editors' Choice 2005
http://mail.yahoo.com