Re: Future of meta-indices: site indexing proposal and Perl script

Tim Berners-Lee <timbl@ptpc00.cern.ch>
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Date: Thu, 24 Mar 1994 17:37:10 --100
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From: Tim Berners-Lee <timbl@ptpc00.cern.ch>
To: Multiple recipients of list <www-talk@www0.cern.ch>
Subject: Re: Future of meta-indices: site indexing proposal and Perl script 
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> 

> Date: Tue, 22 Mar 1994 17:41:08 --100  from rst@ai.mit.edu

>    How about:
> 

>        <meta name="Summary"
>        value="MIT AI lab events, including seminars, conferences, and  
tours">


This suggestion (on www-talk@info.cern.ch) happens to overlap with
an SGML suggestion on uri@bunyip.com, in a discussion of URC
(Universal Resource Citations, aka Metainformation?).
so I cross-post.

Another possibility is to use

	<meta name="summary">
	MIT AI lab events, including seminars, conferences, and tours
	</meta>

which has the advantage that it can be nested:

	<meta name="author">
	    <meta name="name">Jane Doe</meta>
	    <meta name="email">jd@weird.com</meta>
	    <meta name="urn">/people/1967/us/va/12437234hgj3246h</meta>
	</meta>
	
and is equivalnt to the LISP which was also proposed on
the uri list.  This way of using SGML gets around the necessity to
write a DTD every time a new fieled name crops up somewhere,
but has the disadvantage that you can't check it using an
SGML parser (So what? I hear you say).  I am comparing it here with

	<author>
	    <name>Jane Doe</name>
	    <email>jd@weird.com</memail>
	    <urn>/people/1967/us/va/12437234hgj3246h</urn>
	</author>

Perhaps it would be useful to distinguish between two
semantics:

1.   A noun clause for the object which has properties
	urn=sdfgwkedf, height=1237123, fsize=9.5

2.   A *statement* that the object define by
	urn=sdfhjsdf
     has properites
         height=1237123, fsize=9.5
	 

The URC discussion is only considering point 1, but I wonder whether
in fact the information is in fact more of the form of point 2.

<ramble>
Maybe we need a more mathematical expression

	For the book x such that
		x.isbn = 1231231232
	I assert that {
		x.price = $23;
		x.author= y such that {
			y.name="fred"
		}
	}
	
[A x . isbn(x)=12378097 E edition e . format(e,x) & back(e)=hard &  
price(e)=$12 Where "A" and "E" should be rotated through 180 degrees
of course (-:  ]

Rambling into SGML:

<forall id=x>
   <suchthat>
      <meta idref=x name="name">John Doe</meta>
   </suchthat>
   <assert>
      <meta idef=x name="state">ficticious</meta>
   </assert>
</forall>

This is, of course, ridiculous, but there is a serious point in it,especially
for systems which store meta information as retrieval hints.

</ramble>

timbl