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<html xmlns="http://www.w3.org/1999/xhtml">
<head profile="http://www.w3.org/2003/g/data-view
http://purl.org/NET/erdf/profile">
<title>A Pragmatic Theory of Reference</title>
<meta name="copyright"
content="Copyright © 2006 W3C (MIT, ERCIM, Keio)
$Revision: 1.2 $" />
<meta name="Date" content="$Date: 2006/09/13 15:49:16 $" />
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<div class="slide cover">
<img align="right"
src="http://www.w3.org/Talks/Tools/Slidy/keys.jpg"
alt="Cover page images (keys)" class="cover" />
<h1>A Pragmatic Theory of Reference</h1>
<address class="vcard" id="danc">
<a class="url fn n foaf-name" rel="foaf-homepage" href="http://www.w3.org/People/Connolly/"><span class="given-name">Dan</span
> <span class="family-name">Connolly</span></a><br />
</address>
<div class="vevent" id="tp2006">
<a class="url summary foaf-homepage" href="http://www.ibiblio.org/hhalpin/irw2006/">IRW2006</a><br />
<span class="location">Edinburgh, Scotland</span><br />
<abbr class="dtstart" title="2006-05-23">23 May 2006</abbr>
</div>
</div>
<div class="slide"><h1>Outline</h1>
<ul>
<li>Design and Social Dynamics</li>
<li>Web Architecture in brief</li>
<li>A formal notation</li>
<li>A look at httpRange-14</li>
<li>Advice</li>
</ul>
</div>
<div class="slide"><h1>Design and Social Dynamics</h1>
<table border="1" class="compare">
<tr><td> </td><th>Web</th><th>Semantic Web</th></tr>
<tr><th>Traditional Design</th><td>hypertext</td><td>logic/database</td></tr>
<tr><th>+</th><td colspan="2">URIs</td></tr>
<tr><th>-</th><td>link consistency</td><td>?</td></tr>
<tr><th>=</th><td colspan="2">viral growth</td></tr>
</table>
<p>Are there parts of traditional logic and databases that, if we set them
aside, will result in viral growth of the Semantic Web?</p>
</div>
<div class="slide"><h1>URIs, Resources, and Representations</h1>
<div class="figure" style="float:left">
<img alt="fig1"
src="http://www.w3.org/TR/2004/REC-webarch-20041215/uri-res-rep.png" />
</div>
<table class="compare" border="1">
<tr><td> </td><th>Web</th><th>Programming Languages</th><th>Mathematical Logic</th></tr>
<tr><th>Symbols</th><td>URIs</td><td>variables</td><td>constants</td></tr>
<tr><th>Referents</th><td>Resources</td><td>memory cells</td><td>objects in the domain</td></tr>
<tr><th>Values</th><td>Representations</td><td>values</td><td>n/a?</td></tr>
</table>
<p>Note: this is an analogy, not an exact correspondence.</p>
</div>
<div class="slide"><h1>Ambiguity</h1>
<pre>
I saw a great <a
href="http://www.imdb.com/title/tt0091605/"
>movie starring Sean Connery</a>
</pre>
<p>... vs ....</p>
<pre>
The <a
href="http://www.imdb.com/title/tt0091605/"
>IMDB page on "The Name of the Rose"</a>
is a great source of information.
</pre>
<ul>
<li>movie: <cite>The Name of the Rose</cite></li>
<li>page about that movie</li>
</ul>
<p>Which does <tt>http://www.imdb.com/title/tt0091605/</tt> refer to</p>
</div>
<div class="slide"><h1>Ambiguity and delegation</h1>
<ul>
<li>People dismbiguate "I am Dan" and "I call myself Dan" routinely.</li>
<li>In a C program, where <tt>*p</tt> leads to a useful result, <tt>**p</tt> leads to a crash.</li>
<li>Semantic Web is about delegating clear tasks to the machine.</li>
<li>We'll do well to be careful about ambiguity.</li>
</ul>
</div>
<div class="slide"><h1>httpRange-14</h1>
<ul>
<li>W3C Technical Architecture Group (<a
href="http://www.w3.org/2001/tag">TAG</a>) is chartered to <q>document
and build consensus around principles of Web architecture</q>.</li>
<li>Issue <a
href="http://www.w3.org/2001/tag/issues.html#httpRange-14">httpRange-14:
What is the range of the HTTP dereference function?</a>.</li>
<li>discuss. :)</li>
</ul>
</div>
<div class="slide"><h1>The Dublin Core title property</h1>
<pre class="dcmi">
<rdf:Property
rdf:about="http://purl.org/dc/elements/1.1/title">
<rdfs:label xml:lang="en-US"
>Title</rdfs:label>
<!-- ... details elided ... -->
</rdf:Property>
</pre>
</div>
<div class="slide"><h1>dc:title rephrased in Turtle</h1>
<p>Or, equivalently, using turtle<a href="http://www.dajobe.org/2004/01/turtle/">Turtle</a> notation:</p>
<pre class="dcmi">
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix dc: <http://purl.org/dc/elements/1.1/>.
dc:title rdf:type rdf:Property.
</pre>
</div>
<div class="slide"><h1>Borrowing str:notMatches and log:uri</h1>
<pre>
@prefix log: <http://www.w3.org/2000/10/swap/log#> .
@prefix str: <http://www.w3.org/2000/10/swap/string#> .
dc:title log:uri "http://purl.org/dc/elements/1.1/title".
"http://purl.org/dc/elements/1.1/title" str:startsWith "http:".
"http://purl.org/dc/elements/1.1/title" str:notMatches "#".
</pre>
<p>the <tt>log:uri</tt> property is similar to
the <tt>name</tt> quoting function in KIF<a href="urisym#kif">[KIF]</a>.</p>
</div>
<div class="slide"><h1>TimBL's starting position</h1>
<p>Berners-Lee argued that <q>HTTP URIs (without <tt>#</tt>)
should be understood as referring to documents, not cars</q>.</p>
<pre class="tbl">
@prefix owl: <http://www.w3.org/2002/07/owl#>.
@prefix tbl: <http://example/tbl-terms#>.
@forAll ?X, ?URI.
{
?X log:uri ?URI.
?URI str:startsWith "http:".
?URI str:notMatches "#".
} => { ?X a tbl:Document }.
tbl:Document owl:disjointWith tbl:Car.
</pre>
<div class="slide"><h1>Pages vs People</h1>
<pre class="baker">
@prefix foaf: <http://xmlns.com/foaf/0.1/>.
<http://markbaker.ca/> a foaf:Person;
foaf:name "Mark Baker".
</pre>
</div>
</div>
<div class="slide"><h1>An HTTP GET</h1>
<p>Suppose we do a <tt>GET</tt> on <tt class="url">http://site.example/path</tt>
and we get back:</p>
<pre>
200 OK
content-type: text/plain
hello world.
</pre>
<p>Then we'll say:</p>
<pre>
@prefix http: <http://example/http-terms#>.
@prefix mime: <http://example/mime-terms#>.
_:reply1 a http:OKResponse;
http:about <http://site.example/path>;
mime:body "hello world.";
mime:content-type "text/plain".
</pre>
</div>
<div class="slide"><h1>w:representation</h1>
<pre>
@prefix w: <http://example/webarch-terms#>.
{
_:m a http:OKResponse;
http:about ?R;
mime:body ?BYTES; mime:content-type ?TYPE.
} => {
?R w:representation [
mime:content-type ?TYPE; mime:body ?BYTES ].
}
</pre>
</div>
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