--- a/model/working-copy/wd5-prov-dm-derivation.html Sun Mar 04 13:13:28 2012 -0500
+++ b/model/working-copy/wd5-prov-dm-derivation.html Mon Mar 05 09:15:19 2012 +0000
@@ -256,25 +256,25 @@
-<p>According to <a href="#conceptualization">Section Conceptualization</a>, for an entity to be transformed from, created from, or affected by another in some way, there must be some
+<p>According to <a href="#conceptualization">Section Overview</a>, for an entity to be transformed from, created from, or resulting from an update to another, there must be some
underpinning activities performing the necessary actions resulting in such a derivation.
-A generation can be described at various levels of precision. In its simplest form, generation relates two entities. Optionally, attributes can be added to describe modalities of derivation. Again, optionally, time information can be provided, as a convenient way to expression the time at which the entity was generated. If the derivation is the result of a single activity, then it can be optionally expressed. And to provide a completely accurate description of derivation, the generation and usage of the generated and used entities can be provided. </p>
+A derivation can be described at various levels of precision. In its simplest form, derivation relates two entities. Optionally, attributes can be added to describe modalities of derivation. Again, optionally, time information can be provided, as a convenient way to express the time at which the entity was generated. If the derivation is the result of a single activity, then the activity can also be optionally expressed. And to provide a completely accurate description of derivation, the generation and usage of the generated and used entities, respectively, can be provided. </p>
<p><div class="attributes" id="attributes-derivation">A <dfn>derivation</dfn><span class="withAsn">, written <span class="name">wasDerivedFrom(id, e2, e1, a, g2, u1, t, attrs)</span> in PROV-ASN,</span> contains:</p>
<ul>
-<li><em>id</em>: an OPTIONAL identifier identifying the derivation;</li>
-<li><em>generatedEntity</em>: the identifier of the generation entity;</li>
+<li><em>id</em>: an OPTIONAL identifier for a derivation;</li>
+<li><em>generatedEntity</em>: the identifier of the generated entity;</li>
<li><em>usedEntity</em>: the identifier of the used entity;</li>
-<li><em>activity</em>: an OPTIONAL identifier of the activity using and generating the above entities;</li>
-<li><em>generation</em>: an OPTIONAL identifier of the generation for the generated entity and activity;</li>
-<li><em>usage</em>: an OPTIONAL identifier of the usage for the used entity and activity;</li>
+<li><em>activity</em>: an OPTIONAL identifier for the activity using and generating the above entities;</li>
+<li><em>generation</em>: an OPTIONAL identifier for the generation involving the generated entity and activity;</li>
+<li><em>usage</em>: an OPTIONAL identifier for the usage involving the used entity and activity;</li>
<li><em>time</em>: an OPTIONAL "generation time", the time at which the entity was created;</li>
<li><em>attributes</em>: an OPTIONAL set of attribute-value pairs that describe the modalities of this derivation.</li>
</ul>
</div>
-<p> Derivation is not defined to be transitive. Domain-specific specializations of these derivations may be defined in such a way that the transitivity property
+<p> Derivation is not defined to be transitive. Domain-specific specializations of derivation may be defined in such a way that the transitivity property
holds.</p>
@@ -286,22 +286,22 @@
<pre class="codeexample">
wasDerivedFrom(e5,e3,a4,g2,u2)
-wasDerivedFrom(e3,e2)
-
wasDerivedFrom(e2,e1)
wasDerivedFrom(e2,e1,[prov:type="physical transform"])
wasDerivedFrom(e2,e1,2012-01-18T16:00:00)
</pre>
<p>
-The first two are precise-1 derivations expressing that the activity identified by <span class="name">a4</span>, by
-using the entity denoted by <span class="name">e3</span> according to usage <span class="name">u2</span>
+The first description expresses that activity <span class="name">a4</span>,
+using the entity <span class="name">e3</span> according to usage <span class="name">u2</span>
derived the
-entity denoted by <span class="name">e5</span> and generated it according to generation
+entity <span class="name">e5</span> and generated it according to generation
<span class="name">g2</span>. </p>
<p>
-The third line describes an imprecise-1 derivation, which is similar for <span class="name">e3</span> and <span class="name">e2</span>, but it leaves the activity and associated attributes implicit. The fourth and fifth lines are about imprecise-n derivations between <span class="name">e2</span> and <span class="name">e1</span>, but no information is provided as to the number and identity of activities underpinning the derivation. The sixth derivation extends the fifth with the derivation time of <span class="name">e2</span>.
+The second and third lines are about derivations between <span class="name">e2</span> and <span class="name">e1</span>, but no information is provided as to the identity of activity (and usage and generation) underpinning the derivation. In the third line, a type attribute is provided.</p>
+
+<p> The fourth derivation extends the second with the derivation time of <span class="name">e2</span>.
</p>
</div>
@@ -311,14 +311,102 @@
Its name, its default value <a href="http://www.w3.org/2011/prov/track/issues/180">ISSUE-180</a>.
<a href="http://www.w3.org/2011/prov/track/issues/179">ISSUE-179</a>.</div>
+
+<div class='pending'> Is imprecise-1 derivation necessary? Can we just use precise-1 and imprecise-n? <a href="http://www.w3.org/2011/prov/track/issues/249">ISSUE-249</a>.</div>
+
<div class='issue'> Emphasize the notion of 'affected by' <a href="http://www.w3.org/2011/prov/track/issues/133">ISSUE-133</a>.</div>
-<div class='pending'> Is imprecise-1 derivation necessary? Can we just use precise-1 and imprecise-n? <a href="http://www.w3.org/2011/prov/track/issues/249">ISSUE-249</a>.</div>
+</section>
+
+
+<section id="Derivation-Relation">
+<h4>TO GO in PART II: Derivation</h4>
+
+
+<b>Section <a href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm-constraints.html#Derivation-Relation">Derivation-Relation</a> edited as follows</b>.
+
+
+<p>Derivation with are more informative in the presence of activity, generation and usage. Hence, the following implication
+holds.</p>
+<div class='inference' id='derivation-implication'>
+Given two entities denoted by <span class="name">e1</span> and <span class="name">e2</span>, <span class='conditional'>if</span> the assertion <span class="name">wasDerivedFrom(e2,
+e1, a, g2, u1, attrs)</span>
+ holds for some generation <span class="name">g2</span>, usage <span class="name">u1</span>, and set of attribute-value pairs <span class="name">attrs</span>, then <span
+class="name">wasDerivedFrom(e2,e1, attrs)</span> also holds.<br>
+ </div>
+
+<div class="interpretation-forward">
+For the interpretation of a derivation, see <a href="#derivation-usage-generation-ordering">derivation-usage-generation-ordering</a> and <a
+href="#derivation-generation-generation-ordering">derivation-generation-generation-ordering</a>
+</div>
+
+
+<p>
+Note that inferring derivation from usage and generation does not hold
+in general. Indeed, when a generation <span class="name">wasGeneratedBy(g, e2, a, attrs2)</span>
+<a>precedes</a> <span class="name">used(u, a, e1, attrs1)</span>, for
+some <span class="name">e1</span>, <span class="name">e2</span>, <span class="name">attrs1</span>, <span class="name">attrs2</span>, and <span class="name">a</span>, one
+cannot infer derivation <span class="name">wasDerivedFrom(e2, e1, a, g, u)</span>
+or <span class="name">wasDerivedFrom(e2,e1)</span> since
+of <span class="name">e2</span> cannot possibly be derived from
+ <span class="name">e1</span>, given the creation of <span class="name">e2</span> <a>precedes</a> the use
+of <span class="name">e1</span>.
+</p>
+
+
+<p>The effective placeholder for an entity generation time is <a>generation</a>. The presence of
+time information in derivations is merely a convenience notation for a timeless derivation and a generation with this generation time information. </p>
+
+<div class='inference' id="derivation-time-elimination">
+<span class='conditional'>If</span> <span class="name">wasDerivedFrom(e2,e1,t,attrs)</span> holds, <span class='conditional'>then</span> the following expressions also hold:
+<span class="name">wasDerivedFrom(e2,e1,attrs)</span> and <span class="name">wasGeneratedBy(e2,t)</span>.
+</div>
+
+<p></p>
+<div class="structural-forward">
+See <a href="#derivation-use">derivation-use</a> for a structural constraint on derivations.
+</div>
+
+
+
+
+
+<div class='pending'>Several points were raised about the attribute steps.
+Its name, its default value <a href="http://www.w3.org/2011/prov/track/issues/180">ISSUE-180</a>.
+ <a href="http://www.w3.org/2011/prov/track/issues/179">ISSUE-179</a>.</div>
+
+<div class='issue'> Emphasize the notion of 'affected by' <a href="http://www.w3.org/2011/prov/track/issues/133">ISSUE-133</a>.</div>
+
+<div class='pending'> Simplify derivation <a href="http://www.w3.org/2011/prov/track/issues/249">ISSUE-249</a>.</div>
</section>
+
+<section>
+<h4>TO GO in PART 2: PROV-DM Account Constraints</h4>
+
+<b>To replace <a href="http://dvcs.w3.org/hg/prov/raw-file/default/model/prov-dm-constraints.html#derivation-use">derivation-use</a></b>.
+
+
+
+<p>A further inference is permitted from derivations with an explicit activity and no usage: </p>
+<div class='inference' id='derivation-use'>
+<p>Given an activity <span class="name">a</span>, entities denoted by <span class="name">e1</span> and <span class="name">e2</span>, and sets of attribute-value
+pairs <span class="name">dAttrs</span>, <span class="name">gAttrs</span>,
+<span class='conditional'>if</span> <span class="name">wasDerivedFrom(e2,e1, a, dAttrs)</span> and <span class="name">wasGeneratedBy(e2,a,gAttrs)</span> hold, <span
+class='conditional'>then</span> <span class="name">used(a,e1,uAttrs)</span> also holds
+for some set of attribute-value pairs <span class="name">uAttrs</span>.
+</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
+(see <a href="#generation-uniqueness">generation-uniqueness</a>). Hence, this activity is also the one referred to by the usage of <span class="name">e1</span>.
+</p>
+
+
+</section>
+
+
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