Beefy Boxes and Bandwidth Generously Provided by pair Networks
XP is just a number

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
In college, a programming assignment was to write an inference engine in Pascal. Although everyone else in class thought it was a huge deal (a semester-long project) and turned in huge monstrosoties of programs, I thought it was a simple, beautiful, elegant problem, and made a 5-page solution.

So, I think it's easy enough to implement reusable logic to go through a fact base. It would be easy to represent the facts in Perl, too.

The cool thing that Prolog does is "variable unification", and Perl has nothing like that. There was a Perl6 RFC that was dismissed as being too complex and still not complete enough to be worthwhile, and I reciently read about the backtracking scope in the new regex and wondered if that might be made more general, but it's not really the same thing.

I wonder, though, if full-blown Unification is needed to solve the problems with an inference-engine approach. The big deal about it is that it makes tail-end recursion possible (e.g. no cleanup step after the call returns), while doing the same thing with "undo" code living on the stack would mean you really do need to keep a stack of everything you've been though. Today machines have millions of times more storage, so is that an issue?

Also, you would want "how" and "why" features on your inference engine.

You have your fundimental facts and your rules stored in different ways—lists and subs. The subs are hand-written. How is that reusable? I think it illustrates a "pattern" commonly found in code, to solve a complex problem in a top-down manner.

However, I think it would be more interesting to start by expressing your rules as Perl data, in a simple and natural manner:

[owns => 'merlyn', 'gold'], [valuable => 'gold'], [[steals_from => '$X', '$Y'] => [thief => '$X'], [rich => '$Y']
and come up with a fully reusable function that takes this data and makes inferences on it. Here, I used '$X' etc. as placeholders, like variables in Prolog or the questionmark stuff in CLIPS. Seems like you could generate source code on the fly based on the rule!


In reply to Re: AI in Perl - proof of concept by John M. Dlugosz
in thread AI in Perl - proof of concept by Ovid

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.
  • Log In?

    What's my password?
    Create A New User
    and the web crawler heard nothing...

    How do I use this? | Other CB clients
    Other Users?
    Others scrutinizing the Monastery: (6)
    As of 2019-07-17 15:34 GMT
    Find Nodes?
      Voting Booth?

      No recent polls found