--- a/model/ProvenanceModel.html Wed Sep 07 14:37:50 2011 +0100
+++ b/model/ProvenanceModel.html Wed Sep 07 16:09:02 2011 +0100
@@ -1491,25 +1491,34 @@
</ul>
</p>
+<p>A revision expression can only be asserted, since it needs to include an agent bearing responsibility for declaring a variant of a thing. However, it needs to satisfy the following constraint, linking the two entities by a derivation, and seing them as a complement of a third entity.</p>
+
+<div class='constraint' id='wasRevision'>
+Given two identifers <span class="name">old</span> and <span class="name">new</span> denoting two entities, and an identifier <span class="name">ag</span> denoting an agent,
+<span class='conditional'>if</span> an expression <span class="name">wasRevisionOf(new,old,ag)</span> is asserted, <span class='conditional'>then</span>
+there exists an entity <span class="name">e</span> and attribute-values <span class="name">av</span>, such that the following expressions hold:
+<ul>
+<li> <span class="name">wasEventuallyDerivedFrom(new,old)</span>;
+<li> <span class="name">entity(e,av)</span>;
+<li> <span class="name">wasComplement(new,e)</span>;
+<li> <span class="name">wasComplement(old,e)</span>.
+</ul>
+</div>
+
+<p><span class="name">wasRevisionOf</span> is a strict sub-relation
+ of <span class="name">wasEventuallyDerivedDerivedFrom</span> since two entities <span class="name">e2</span> and <span class="name">e1</span>
+ may satisfy <span class="name">wasEventuallyDerivedDerivedFrom(e2,e1)</span> without being a variant of
+ each other.
+</p>
<p>
-From an assertion <span class="name">wasRevisionOf(new,old,ag)</span>, one can infer that:
-<ul>
-<li> The characterized thing denoted by <span class="name">new</span> is derived from the characterized thing denoted by <span class="name">old</span>
-<li> There exists an entity <span class="name">X</span>, such that:
-<ul>
-<li> <span class="name">new</span> wasComplementOf <span class="name">X</span>;
-<li> <span class="name">old</span> wasComplementOf <span class="name">X</span>;
-<li> <span class="name">X</span> MAY have been asserted.
-</ul>
-</ul>
+The following revision assertion
+<pre class="example">
+wasRevisionBy(e3,e2,a4)
+</pre>
+states that the document represented by entity identified by <span class="name">e3</span> is declared to be revision of document represented by entity identified by <span class="name">e2</span> by agent denoted by <span class="name">a4</span>.
</p>
-<p><span class="name">wasRevisionOf</span> is a strict sub-relation
- of <span class="name">wasDerivedFrom</span> since two entities <span class="name">e2</span> and <span class="name">e1</span>
- may satisfy <span class="name">wasDerivedFrom(e2,e1)</span> without being a variant of
- each other.
-</p>
<div class='pending'>Revision should be a class not a property. This is <a href="http://www.w3.org/2011/prov/track/issues/48">ISSUE-48</a>.</div>