--- a/rdf-concepts/index.html Thu Nov 08 20:10:30 2012 +0000
+++ b/rdf-concepts/index.html Fri Nov 09 10:35:29 2012 +0000
@@ -308,6 +308,77 @@
</section>
+<section id="change-over-time">
+ <h2>RDF and Change Over Time</h2>
+
+ <p>The RDF data model is <em>atemporal</em>: It does not deal with time,
+ and does not have a built-in notion of temporal validity of information.
+ <a title="RDF graph"</a>RDF graphs</a> are static snapshots of
+ information.</p>
+
+ <p>However, <a title="RDF graph">RDF graphs</a> can express information
+ about events and about temporal aspects of other entities,
+ given appropriate <a title="RDF vocabulary">vocabulary</a> terms.</p>
+
+ <p>Since <a title="RDF graph">RDF graphs</a> are defined as mathematical
+ sets, adding or removing <a title="RDF triple">triples</a> from an
+ RDF graph yields a different RDF graph.</p>
+
+ <p>We informally use the term <dfn>g-box</dfn> to refer to a
+ persistent yet mutable source or container of
+ <a title="RDF graph">RDF graphs</a>. A g-box is a <a>resource</a>
+ that may be said to have a state that can change over time.
+ A snapshot of the state can be expressed as an RDF graph.
+ For example, any web document that has an RDF-bearing representation
+ may be considered a g-box. Like all resources, <a>g-boxes</a> may
+ be named with <a title="IRI">IRIs</a> and therefore described in
+ other RDF graphs.</p>
+
+ <p class="issue">“G-box” is a placeholder term. What term should
+ we use instead? This is <a href="https://www.w3.org/2011/rdf-wg/track/issues/110">ISSUE-110</a>.</p>
+
+ <p>While this is not explicitly captured in the data model or its
+ formal semantics, intuitively speaking, changes in the world
+ are reflected in an RDF description of the world in the following way:</p>
+
+ <ul>
+ <li>An <a>IRI</a>, once <a title="minting">minted</a>, should never
+ change its <a>referent</a>. (See
+ <a href="http://www.w3.org/TR/webarch/#URI-persistence">URI
+ persistence</a> [[WEBARCH]].)</li>
+ <li><a title="literal">Literals</a>, by design, are constants and
+ never change their <a title="literal value">value</a>.</li>
+ <li>Some <a title="property">properties</a> may change over time.
+ A relationship that holds between two <a title="resource">resources</a>
+ at one time may not hold at another time.</li>
+ <li><a title="g-box">G-boxes</a> may change their state over time.
+ That is, they may contain different <a title="RDF graph">RDF graphs</a>
+ at different times.</li>
+ <li>Some <a title="g-box">g-boxes</a> may, however, be immutable
+ snapshots of another g-box, archiving its state at some
+ point in time.</li>
+ </ul>
+
+</section>
+
+
+<section id="managing-graphs">
+ <h3>Merging and Managing RDF Graphs</h3>
+
+ <p class="issue">This section should explain terminology around
+ <a href="#section-dataset">working with multiple graphs</a>,
+ and explain the fact that graphs merge easily.
+ This will be added once the Working Group has finalised a design.</p>
+
+ <p class="issue">If RDF Concepts defines graph stores, then they should be mentioned here.</p>
+
+ <p>An <dfn>RDF document</dfn> is a document that encodes an
+ <a>RDF graph</a> in a <dfn>concrete RDF syntax</dfn>, such as
+ Turtle [[TURTLE-TR]], RDFa [[RDFA-PRIMER]], RDF/XML [[RDF-SYNTAX-GRAMMAR]],
+ or N-Triples [[N-TRIPLES]].</p>
+</section>
+
+
<section id="entailment">
<h3>Formal Meaning and Entailment</h3>
@@ -352,57 +423,6 @@
</section>
-<section id="managing-graphs">
- <h3>Merging and Managing RDF Graphs</h3>
-
- <p class="issue">This section should explain terminology around
- <a href="#section-dataset">working with multiple graphs</a>,
- and explain the fact that graphs merge easily.
- This will be added once the Working Group has finalised a design.</p>
-
- <p>An <dfn>RDF document</dfn> is a document that encodes an
- <a>RDF graph</a> in a <dfn>concrete RDF syntax</dfn>, such as
- Turtle [[TURTLE-TR]], RDFa [[RDFA-PRIMER]], RDF/XML [[RDF-SYNTAX-GRAMMAR]],
- or N-Triples [[N-TRIPLES]].</p>
-</section>
-
-
-<section id="change-over-time">
- <h2>RDF and Change Over Time</h2>
-
- <p class="issue">This sub-section is a rough draft and needs further editorial attention.</p>
-
- <p>The RDF data model does not deal with time; it is <em>atemporal</em>.
- RDF graphs (and RDF datasets) can be considered static snapshots.
- There is no built-in notion of temporal validity or change.</p>
-
- <p>However, RDF can be used to express information about events
- and about temporal aspects of other entities,
- given appropriate vocabulary terms.</p>
-
- <p>While this is not explicitly captured in the data model or its
- formal semantics, intuitively speaking, change is handled like this:</p>
-
- <ul>
- <li>New IRIs can be introduced (<dfn title="minting">minted</dfn>)
- to refer to new entities</li>
- <li>Once minted, IRIs don't change their referents</li>
- <li>Literals never change their values</li>
- <li>Some properties may change over time; that is,
- a relationship between two resources that holds at one time
- may not hold at another time</li>
- <li>Some g-boxes may change their contents over time;
- that is, they may contain different RDF graphs at different times</li>
- <li>Some g-boxes may be immutable snapshots of another g-box,
- archiving its state at some point in time</li>
- </ul>
-
- <p class="issue">“G-box” is a placeholder term.</p>
-
- <p class="issue">If RDF Concepts defines graph stores, then they should be mentioned here.</p>
-</section>
-
-
</section>
@@ -1200,7 +1220,7 @@
semantic notions of <a>entailment</a> are usually more helpful
than syntactic <a>graph isomorphism</a>.</p>
- <p class="issue">What does it mean when a literal is ill-typed or when something is not in the datatype map? What should an implementation do? Should authors avoid generating such graphs? Should consumers reject it? Is an implementation that rejects ill-formed xsd:dates conforming?</p>
+ <p class="issue">What does it mean when a literal is ill-typed or when something is not in the datatype map? What should an implementation do? Should authors avoid generating such graphs? Should consumers reject it? Is an implementation that rejects ill-formed xsd:dates conforming? This is <a href="https://www.w3.org/2011/rdf-wg/track/issues/109">ISSUE-109</a>.</p>
</section>