--- a/model/working-copy/prov-dm-constraints.html Tue Feb 14 05:11:12 2012 +0000
+++ b/model/working-copy/prov-dm-constraints.html Tue Feb 14 05:54:35 2012 +0000
@@ -253,81 +253,7 @@
<section id='preliminaries'>
<h2>Data Model Refinement</h2>
-
- <section id='section-attributes'>
-<h4>Attributes</h4>
-
-
- <section id='section-entity-activity-agent'>
-<h4>Entity, Activity, Agent</h4>
-
-
-
-
-<p>This specification is based on a conceptualization of the world
-that is described in this section. In the world (whether real or not),
-there are things, which can be physical, digital, conceptual, or
-otherwise, and activities involving things. </p>
-
-<p>When we talk about things in the world in natural language and even when we assign identifiers, we are often imprecise in ways that make it difficult to clearly and unambiguously report
-provenance: a resource with a URL may be understood as referring to a report available at that URL, the version of the report available there today, the report independent of where it is
-hosted over time, etc.</p>
-
-<p>Hence, to accommodate different perspectives on things and their situation in the world as perceived by us, we introduce the idea of a characterized thing, which refers to a thing and its
-situation in the world, as characterized by someone. We then define an <dfn id="concept-entity">entity</dfn> as an identifiable characterized thing. An entity <em>fixes some aspects</em> of
-a thing and its situation in the world, so that it becomes possible to express its provenance, and what causes these specific aspects to be as such. An alternative entity may fix other
-aspects, and its provenance may be different.</p>
-
-<div class="anexample" id="a-report-example">
-Different users may take different perspectives on a resource with
-a URL. These perspectives in this conceptualization of the world are
-referred to as entities. Three such entities may be
-expressed:
-<ul>
-<li>a report available at a URL: fixes the nature of the thing, i.e. a document, and its location; </li>
-<li>the version of the report available there today: fixes its version number, contents, and its date;</li>
-<li>the report independent of where it is hosted and of its content over time: fixes the nature of the thing as a conceptual artifact.</li></ul>
-The provenance of these three entities may differ, and may be along the following lines:
-<ul>
-<li>the provenance of a report available at a URL may include: the act of publishing it and making it available at a given location, possibly under some license and access control;</li>
-<li>the provenance of the version of the report available there today may include: the authorship of the specific content, and reference to imported content;</li>
-<li>the provenance of the report independent of where it is hosted over time may include: the motivation for writing the report, the overall methodology for producing it, and the broad team
-involved in it.</li>
-</ul>
-</div>
-
-<p>We do not assume that any characterization is more important than any other, and in fact, it is possible to describe the processing that occurred for the report to be commissioned, for
-individual versions to be created, for those versions to be published at the given URL, etc., each via a different entity that characterizes the report appropriately.</p>
-
-<p>In the world, <dfn id="concept-activity">activities</dfn> involve
-entities in multiple ways: consuming them, processing them,
-transforming them, modifying them, changing them, relocating
-them, using them, generating them, being associated with them,
-etc.</p>
-
-
-<p>An <dfn id="concept-agent">agent</dfn> is a type of entity that takes an active role in an activity such that it can be assigned some degree of responsibility for the activity taking
-place.
-This definition intentionally stays away from using concepts such as enabling, causing, initiating, affecting, etc, because any entities also enable, cause, initiate, and affect in some way
-the activities. So the notion of having some degree of responsibility is really what makes an agent. </p>
-
-<p> Even software agents can be assigned some responsibility for the effects they have in the world, so for example if one is using a Text Editor and one's laptop crashes, then one would say
-that the Text Editor was responsible for crashing the laptop. If one invokes a service to buy a book, that service can be considered responsible for drawing funds from one's bank to make
-the purchase (the company that runs the service and the web site would also be responsible, but the point here is that we assign some measure of responsibility to software as well). So when
-someone models software as an agent for an activity in our model, they mean the agent has some responsibility for that activity.
-</p>
-
-<p>PROV-DM considers agents as a type of entity so that the model can be
- used to represent the provenance of the agents themselves. For
- example, a grammarchecker software may be an agent of a document
- preparation activity, but itself can have a provenance record that
- states who its vendor is.</p>
-
-
-<p> In this specification, the qualifier 'identifiable' is implicit whenever a reference is made to an activity, agent, or an entity.</p>
-
-</section>
-</section>
+<p>Underpinning the PROV-DM data model is a notion of event, marking transitions in the world (when entities are generated, used, or destroyed, or activities started or ended). This notion of event is not first-class in the data model, but underpins many of its concepts and its semantics. Thus, using this notion of event, we can refine the data model, and hereby allowing creators of provenance assertions to make their assertions more robust. </p>
<section id='section-time-event'>
@@ -371,6 +297,12 @@
<p>An <dfn id="dfn-usage-event">entity usage event</dfn> is the <a title="event">instantaneous event</a> that marks the first instant of an entity's consumption timespan by an activity.</p>
+<p>An <dfn id="dfn-destruction-event">entity destruction event</dfn> is the <a title="event">instantaneous event</a> that marks the initial instant of an entity's destruction timespan, after which
+it no longer becomes available for use.</p>
+
+<div class='note'>Tentative definition of destruction!</div>
+
+
<p>An <dfn id="dfn-start-event">activity start event</dfn> is the <a title="event">instantaneous event</a> that marks the instant an activity starts.</p>
<p>An <dfn id="dfn-end-event">activity end event</dfn> is the <a title="event">instantaneous event</a> that marks the instant an activity ends.</p>
@@ -424,11 +356,66 @@
</section>
-<div class='issue'> We need to refine the definition of entity and activity, and all the concepts in general. This is <a href="http://www.w3.org/2011/prov/track/issues/223">ISSUE-223</a>.</div>
</section>
+ <section id='section-attributes'>
+<h4>Entities and Attributes</h4>
+
+<p>When we talk about things in the world in natural language and even when we assign identifiers, we are often imprecise in ways that make it difficult to clearly and unambiguously report
+provenance: a resource with a URL may be understood as referring to a report available at that URL, the version of the report available there today, the report independent of where it is
+hosted over time, etc.</p>
+
+<p>From a provenance viewpoint, it is important to identify a "<em>partial state</em>" of something, i.e. something with some aspects that have been fixed, so that it becomes possible to express its provenance, and what causes that thing, with these specific aspects to be as such. </p>
+
+<p>It is the purpose of attributes in PROV-DM to help fix some aspect of entities.
+Indeed, we previously defined
+entities are things in the world one wants to provide provenance for;
+we refine this definition as follows, using attribute-values to describe entities' "partial states", and linking them to the very existence of entities.</p>
+
+<p>
+An <dfn>entity</dfn> is a thing in the world one wants to provide provenance for and whose situation in the world is represented by some attribute-value pairs; an entity's attribute-value pairs remain unchanged during an entity's characterization interval, which is defined as the period comprised between its <a title="entity generation event">generation event</a> and its <a title="entity destruction event">destruction event</a>.</p>
+
+<p>An entity fixes some aspects of a thing and its situation in the
+world. An alternative entity may fix other aspects, and its provenance
+may be different.</p>
+
+
+ <section id='section-entity-activity-agent'>
+<h4>Entity, Activity, Agent</h4>
+
+
+
+
+
+<div class="anexample" id="a-report-example">
+Different users may take different perspectives on a resource with
+a URL. These perspectives in this conceptualization of the world are
+referred to as entities. Three such entities may be
+expressed:
+<ul>
+<li>a report available at a URL: fixes the nature of the thing, i.e. a document, and its location; </li>
+<li>the version of the report available there today: fixes its version number, contents, and its date;</li>
+<li>the report independent of where it is hosted and of its content over time: fixes the nature of the thing as a conceptual artifact.</li></ul>
+The provenance of these three entities may differ, and may be along the following lines:
+<ul>
+<li>the provenance of a report available at a URL may include: the act of publishing it and making it available at a given location, possibly under some license and access control;</li>
+<li>the provenance of the version of the report available there today may include: the authorship of the specific content, and reference to imported content;</li>
+<li>the provenance of the report independent of where it is hosted over time may include: the motivation for writing the report, the overall methodology for producing it, and the broad team
+involved in it.</li>
+</ul>
+</div>
+
+<p>We do not assume that any characterization is more important than any other, and in fact, it is possible to describe the processing that occurred for the report to be commissioned, for
+individual versions to be created, for those versions to be published at the given URL, etc., each via a different entity that characterizes the report appropriately.</p>
+
+
+</section>
+</section>
+
+
+
<section id="representation-record-assertion-inference">
<h3>Representation, Record, Assertion, and Inference</h3>
@@ -477,6 +464,8 @@
</section>
+<div class='issue'> We need to refine the definition of entity and activity, and all the concepts in general. This is <a href="http://www.w3.org/2011/prov/track/issues/223">ISSUE-223</a>.</div>
+
</section>