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Re: car color defaults: a story about Scoped Negation As Failure/log:notIncludes

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 07 Jul 2005 17:13:19 -0400
Message-ID: <42CD9AEF.70107@research.bell-labs.com>
To: public-rule-workshop-discuss@w3.org

> Here's a sort of story we've written to explain and motivate
> log:notIncludes, aka Scoped Negation As Failure[1].
> 
> [[
> Because a formula is a finite size,
> [...]
> ]]
>  -- section "Implementing defaults and log:notIncludes" 
>   of part "Reaching out onto the Web"
>   of the Semantic Web Tutorial Using N3
>   http://www.w3.org/2000/10/swap/doc/Reach#Implementi


This isn't really the case in examples like:

[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[
To do some inference within another set of rules, a useful relationship 
is that between a formula,
and the result of thinking about it - running any rules in the formula 
on all the data,
recursively just like cwm's --think command line option. This 
relationship is log:conclusion.
To make the initial formula, you can use log:conjunction to merge a list 
of formulae.

  {   ( <input.data>.log:semantics
        <axioms.n3>.log:semantics
        <system-rules.n3>.log:semantics ) log:conjunction :f.
      :f log:conclusion :g.
      :g log:notIncludes {  :request a :ValidRequest }
  } => {
      :request a InvalidRequest
  }.

  This means: if what you get by taking the input data, the axioms and 
  the system rules together and thinking about it doesn't tell you that the
  request is valid, then it is invalid.

   -- section "Thinking inside thinking with log:conclusion"
    of part "Reaching out onto the Web"
    of the Semantic Web Tutorial Using N3
    http://www.w3.org/2000/10/swap/doc/Reach
]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]]

Of course, it may be that cwm is so incomplete that a finite set of 
premises always has a finite set of conclusions, but this is not true in 
many formalisms, including the formalism (forward-chaining rules with 
existentials in the consequent, as seen in 
http://www.w3.org/2003/Talks/0520-www-tf1-b3-rules/slide15-0.html) that 
appears to underly cwm.

[...]

> Dan Connolly, W3C http://www.w3.org/People/Connolly/
> D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E

Peter F. Patel-Schneider
Bell Labs Research
Received on Thursday, 7 July 2005 21:13:44 GMT

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