--- a/model/working-copy/towards-wd4.html Fri Feb 03 20:21:32 2012 +0100
+++ b/model/working-copy/towards-wd4.html Fri Feb 03 21:39:10 2012 +0100
@@ -185,52 +185,31 @@
-<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>
+<p><dfn id="concept-entity">Entities</dfn> are things in the world one
+ wants to provide provenance for. For the purpose of this
+ specification, things can be physical, digital, conceptual, or
+ otherwise; the world may be real or imaginary.
+</p>
+
+
+<div class="anexample" id="entities-example">
+An entity may be a web page at a URI, a file in a file system, a car or an idea.
</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>
+<div class="anexample" id="entities-example">
+An activity may be the publishing of a document on the web, tweeting, extracting metadata from a file, or driving a car.
+</div>
<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>
+This definition intentionally stays away from using concepts such as enabling, causing, initiating, affecting, etc, because many 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. Three types of agents are recognized by PROV-DM because they are commonly encountered in application making data and documents available on the Web: persons, software agents, and organizations.</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
@@ -245,62 +224,34 @@
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 id="representation-record-assertion-inference">
-<h3>Representation, Record, Assertion, and Inference</h3>
-
-<p>
-PROV-DM is a provenance data model designed to express <em>representations</em> of the world. Such representations are structured according to a set of <em>records</em>.
-</p>
-
-<div class="anexample">
-A file at some point during its lifecycle, which includes multiple edits by multiple people, can be represented by its location in the file system, a creator, and content.
-</div>
-
-
-<p>
-These records are relative to an asserter, and in that sense constitute assertions stating properties of the world, as represented by an asserter. Different asserters will normally
-contribute different records expressive different representations of the world.
-This specification does not define a notion of consistency between different sets of records (whether by the same asserter or different asserters).
-The data model provides the means to associate attribution to assertions.
+ <section id="generation-usage-derivation">
+<h3>Generation, Usage, Derivation</h3>
+
+<p>Activities and entities are associated with each other in two different ways: activities are consumers of entities and activities are producers of entities. For provenance purpose, we define the following notions of generation and usage. </p>
+
+<p><dfn id="concept-generation">Generation</dfn> is the completed production of a new entity by activity.
+ This entity become available for usage after this generation. This entity did not exist before generation. </p>
+
+<p><dfn id="concept-usage">Usage</dfn> is an activity beginning to consume an entity.
+Before usage, the activity had not begun to consume or use to this entity (and could not have been affected by the entity).</p>
</p>
-<div class="anexample">
-An alternative representation of the above file is a set of blocks in a hard disk.
+<div class="anexample" id="generation-usage-example">
+<p>Examples of generation are the completed creation of a file by a
+program, the completed creation of a linked data set, the completed
+publication of a new version of a document, and the complete sending
+of a value on a communication channel. </p>
+
+<p>Usage examples include a procedure beginning to consume a parameter, a service starting to read a value on a port, a program beginning to read a configuration
+file, or the point at which an ingredient, such as eggs, is being added in a baking activity. Usage may entirely consume an entity (e.g. eggs are not longer available after being added to
+the mix), or leave it as such, ready for further uses (e.g. a file on a file system can be read indefinitely).</p>
</div>
-<p>The data model is designed to capture activities that happened in the past, as opposed to activities
-that may or will happen.
-However, this distinction is not formally enforced.
-Therefore, all PROV-DM records SHOULD be interpreted as a description of what has happened, as opposed to what may or will happen.</p>
-
-
-
-<p>
-This specification does not prescribe the means by which an asserter arrives at records; for example, records can be composed on the basis of observations, reasoning, or any other means.
-</p>
-
-
-<p>
-Sometimes, inferences about the world can be made from records
-conformant to the PROV-DM data model. When this is the case, this
-specification defines such inferences, allowing new provenance records
-to be inferred from existing ones. Hence, representations of the world
-can result either from direct assertions of records by asserters or from inference of new records
-by application of inference rules defined by this specification.
-</p>
-
-
-
-</section>
</section>
</section>