# 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 17:18:15 -0400 (EDT)
Message-Id: <20050707.171815.17359039.pfps@research.bell-labs.com>

```
> 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 21:18:20 UTC

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