--- a/model/prov-constraints.html	Tue Jul 03 22:39:46 2012 +0100
+++ b/model/prov-constraints.html	Wed Jul 04 09:02:06 2012 +0100
@@ -819,11 +819,27 @@
 <h3>Component 2: Derivations</h3>
 
 
- <p>Derivations with an explicit activity and no usage admit the
-  following inference: </p>
+<hr>
+<p id='derivation-generation-use_text'>Derivations with explicit activity, generation, and usage admit the  following inference: </p>
+<div class="note">
+Luc: Here in first case, we really mean id2 specified (irrespective of _id1 specified), in the second case, we mean id1 specified (irrespective of _id2 specified).
+</div>
+<div class='inference' id='derivation-generation-use'>
+<p>
+<ol>
+<li><span class='conditional'>IF</span> <span class="name">wasDerivedFrom(_id;e2,e1,a,id2,_id1,_attrs)</span>, <span class='conditional'>THEN</span> <span class="name">wasGeneratedBy(id2;e2,a,-)</span>
+<li><span class='conditional'>IF</span> <span class="name">wasDerivedFrom(_id;e2,e1,a,_id2,id1,_attrs)</span>, <span class='conditional'>THEN</span>  <span class="name">used(id1;a,e1,-)</span>
+</ol>
+</div>
+<p>
+<hr>
+<p id='derivation-use_text'>Derivations with an explicit activity and no usage admit the  following inference: </p>
+<div class="note">
+Luc: Here we really mean, no usage, no generation specified. What notation do we use?
+</div>
 <div class='inference' id='derivation-use'>
-<p>Given an activity <span class="name">a</span>, and entities  denoted by <span class="name">e1</span> and <span class="name">e2</span>, 
-<span class='conditional'>IF</span> <span class="name">wasDerivedFrom(-;e2,e1, a, -, -)</span> and <span class="name">wasGeneratedBy(-;e2,a,-)</span> hold, <span
+<p>
+<span class='conditional'>IF</span> <span class="name">wasDerivedFrom(_id;e2,e1,a, -, -,_attrs)</span> and <span class="name">wasGeneratedBy(_id2;e2,a,_t2,_attrs2)</span> hold, <span
 class='conditional'>THEN</span> <span class="name">used(-;a,e1,-)</span> also holds.
 </div>
 <p>This inference is justified by the fact that the entity denoted by <span class="name">e2</span> is generated by at most one activity in a given account