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Re: 1st version exercise 3.16 sequence predication problem

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  • chenyu468
    ... 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 ... further ... According
    Message 1 of 3 , Nov 15, 2003
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      --- 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
      > 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?)

      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


      >
      > 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
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