- I'm not sure what you mean by "dead end". If a node can be broken

down, into a new center node and two leaves, then at some point, the

whole process will stop because there are no more operations to be

performed. (In other words, how can you break down 2 down any further

than 1 + 1 in the operations given?)

I think that you are breaking things down too far. If you have a tree

with all 1's or n's at leaf nodes and +,-,/, or * in the internal

nodes, then the problem seems to indicate that that should be your

goal condition.

This is speculation, since I haven't worked through the problem

myself, but these are my initial impressions.

Brandon

--- In aima-talk@yahoogroups.com, "chenyu468" <chenyu468@y...> wrote:

> hi everyone,

> 1. According to the guide, it is necessary to build a binary-tree for

> representing the "state". The tree's leaves are "1" or "n" and

> internal nodes are "+" "-" "*" "/" "exp" operator.

>

> 1. I don't know how to check the "dead end" for expression. If

> no "dead end" check, it seems that only "breadth_first_search" is

> acceptable. The the speed and space complexity is too high.

>

> 2. the "action" set for replacing "1" is 16 (20-4) by deleting "n

> divide n", "1 divide 1", "1 multiply 1", "exp(1,1)", "

> for replacing "n" is also 16 for the similar reason.

> The expanding branch factor is too high (16). How to reduce it?

>

> 3. I don't know how to identify the "same state" from different path

> for avoiding expanding them. Could you tell me? Or is it possible to

> create unique tree everytime, therefore no need to identify them are

> the same state or not?

>

> Thank you in advance.

> kind regards/chenyu - --- In aima-talk@yahoogroups.com, "Brandon Corfman" <bcorfman@a...>

wrote:> I'm not sure what you mean by "dead end".

What I means:

"dead end" means "It is impossible to further expand the node, that's

no possible action"

If a node can be broken> down, into a new center node and two leaves, then at some point, the

further

> whole process will stop because there are no more operations to be

> performed. (In other words, how can you break down 2 down any

> than 1 + 1 in the operations given?)

According the books guide, it is allowed to break down

("expand") "1+1". For example:

1. replace the first "1" in "1+1" state by "(1+1)+1

2. replace the first "1" in "1+1" state by "(1+n)+1

3. replace the first "1" in "1+1" state by "(n+n)+1

4. replace the first "1" in "1+1" state by "(n+1)+1 (One of my

question is "delete this action or not, because this is same as above

item "2")

5. replace the first "1" in "1+1" state by "(1-1)+1

6. replace the first "1" in "1+1" state by "(n-1)+11.

7. replace the first "1" in "1+1" state by "(n-n)+1

7. replace the first "1" in "1+1" state by "(1-n)+1

...

...

...

Thank you for your attention.

kind regards/chenyu

>

tree

> I think that you are breaking things down too far. If you have a

> with all 1's or n's at leaf nodes and +,-,/, or * in the internal

wrote:

> nodes, then the problem seems to indicate that that should be your

> goal condition.

>

> This is speculation, since I haven't worked through the problem

> myself, but these are my initial impressions.

>

> Brandon

>

> --- In aima-talk@yahoogroups.com, "chenyu468" <chenyu468@y...>

> > hi everyone,

for

> > 1. According to the guide, it is necessary to build a binary-tree

> > representing the "state". The tree's leaves are "1" or "n" and

path

> > internal nodes are "+" "-" "*" "/" "exp" operator.

> >

> > 1. I don't know how to check the "dead end" for expression. If

> > no "dead end" check, it seems that only "breadth_first_search" is

> > acceptable. The the speed and space complexity is too high.

> >

> > 2. the "action" set for replacing "1" is 16 (20-4) by deleting "n

> > divide n", "1 divide 1", "1 multiply 1", "exp(1,1)", "

> > for replacing "n" is also 16 for the similar reason.

> > The expanding branch factor is too high (16). How to reduce it?

> >

> > 3. I don't know how to identify the "same state" from different

> > for avoiding expanding them. Could you tell me? Or is it possible

to

> > create unique tree everytime, therefore no need to identify them

are

> > the same state or not?

> >

> > Thank you in advance.

> > kind regards/chenyu