Re: Uncertainty and Lisa

So, let me get a few things straight in my head. In PAIP there are three
distinct classes of CFs; as you read these examples, note carefully the
suggested Lisa syntax for the new CF support:

  1. A => C, B => C. Two distinct rules, same "piece of evidence", or "fact"
in Lisa's terminology. In this case we use the combination formula described
on pg. 534. In Lisa, this could be written as:

      (defrule A () => (assert (C) :cf 0.6))
      (defrule B () => (assert (C) :cf 0.4))

  2. A and B => C. Single rule with a conjuction. In this case a CF for C is
calculated by taking the min of A's CF and B's CF. In Lisa:

     (defrule frodo ()
       (?a (A))
       (?b (B))
       =>
       (assert (C) :cf (combine ?a ?b)))

3. A and B => .9 C. The rule itself is uncertain. In Lisa:

   (defrule frodo (:cf 0.9)
     (?a (A))
     (?b (B))
     =>
     (assert (C) :cf (combine ?a ?b)))

Ignoring implementation details for now, please comment on the suggested
Lisa syntax and my supposed understanding of the issues. Does it correctly
reflect PAIP's CF theory? The syntax in examples (2) and (3) expects the
programmer to supply the CF by calling the COMBINE method (which "does the
right thing" behind the curtain). Is this satisfactory?

Thanks very much.

David E. Young

"For wisdom is more precious than rubies,
and nothing you desire can compare with her."
  -- Prov. 8:11

"But all the world understands my language."
  -- Franz Joseph Haydn (1732-1809)


----- Original Message ----- 
From: "Paolo Amoroso" <[email protected]>
To: <[email protected]>
Sent: Monday, September 13, 2004 1:35 PM
Subject: [lisa] Re: [Lisa-users] Uncertainty and Lisa

> Here is a
   (defrule A (:cf 0.9)
     (?a (A))
     (?b (B))
     =>
     (assert (C) :cf (combine ?a ?b)))
 sample rule from the MYCIN implementation of PAIP:
>
>   (defrule 52
>     if (site culture is blood)
>        (gram organism is neg)
>        (morphology organism is rod)
>        (burn patient is serious)
>     then .4
>        (identity organism is pseudomonas))
>
> Where .4 is the cf.  I think a syntax like the following is similar in
> spirit to PAIP's:
>
>   (defrule name (key*) pattern* => cf action*)
>
>
> Paolo
> -- 
> Why Lisp? http://alu.cliki.net/RtL%20Highlight%20Film
>
>
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