--- a/model/ProvenanceModel.html	Thu Oct 06 22:36:37 2011 +0100
+++ b/model/ProvenanceModel.html	Thu Oct 06 22:46:43 2011 +0100
@@ -743,6 +743,10 @@
 to know exactly what makes one entity a constrained view of another.
 This is raised in the following <a href="http://lists.w3.org/Archives/Public/public-prov-wg/2011Sep/0315.html">email</a>.</div>
 
+<div class='issue'>The characterization interval of an entity expression is currently implicit. Making it explicit would allow us to define wasComplementOf more precisely. It would also allow us to address 
+<a href="http://www.w3.org/2011/prov/track/issues/108">ISSUE-108</a>.
+Beginning and end of characterization interval could be expressed by attributes (similarly to process executions). </div>
+
 
  
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/model/satya-comments-issue-100.txt	Thu Oct 06 22:46:43 2011 +0100
@@ -0,0 +1,81 @@
+
+  > My review comments for Section 5.2.1 Entity in the current version of the conceptual model document:
+  > 
+  > 1. In PROV-DM, an entity expression is a representation of an
+  > identifiable characterized thing.
+  > 
+  > Issue: Since the section heading is for Entity and the PROV DM
+  > component is Entity, I am confused why we are defining "Entity
+  > Expression" and not "Entity"?
+
+An instance of an entity expression is syntactally written as 'entity',
+but we use the term 'entity expression' to make it clear that we
+refer to a PROV-DM construct (see intro of section 5.1)
+
+  > 
+  > 2. An instance of an entity expression, noted entity(id, [ attr1=val1,
+  > ...]) in PROV-ASN contains an identifier id identifying a
+  > characterized thing; contains a set of attribute-value pairs [
+  > attr1=val1, ...], representing this characterized thing's situation in
+  > the world.
+  > 
+  > Issue: When we refer to an entity in provenance assertions (in
+  > different applications), do we use the identifier to refer to it or
+  > both identifier + attribute-value pairs?
+
+Not sure I understand (in different applications).
+
+We refer to it with its identifier.
+
+  > 
+  > 3. The assertion of an instance of an entity expression, entity(id, [
+  > attr1=val1, ...]), states, from a given asserter's viewpoint, the
+  > existence of an identifiable characterized thing, whose situation in
+  > the world is represented by the attribute-value pairs, which remain
+  > unchanged during a characterization interval, i.e. a continuous
+  > interval between two events in the world.
+  > 
+  > Issue: Are the terms "characterization interval" and "continuous
+  > interval" defined by time values? What do we mean by "continuous
+  > interval" between two events?
+
+We assumed a partial order between events.
+An interval between events a and b [a,b] is the set of events x  such that a<= x and x<=b.
+
+Does it really need to be defined explicitly?
+
+  > 
+  > 4. If an asserter wishes to characterize a thing with the same
+  > attribute-value pairs over several intervals, then they are required
+  > to assert multiple entity expressions, each with its own identifier
+  > (so as to allow potential dependencies between the various entity
+  > expressions to be expressed).
+  > 
+  > Issue: If a thing with same attribute-value pairs exists over several
+  > time? intervals - what will be the dependencies between the various
+  > entity expressions (since entity expressions = identifier +
+  > attribute-value pairs)? If they are different versions of an entity,
+  > they will have distinguishing attributes other than the simple
+  > occurrence at different points of time. Further, we multiple entity
+  > identifiers are used to refer to the same entity, then how do we
+  > reconcile them later?
+
+The example of "luc in boston" in January and June has been discussed extensively.
+That theroretically, we can find distinguishing attributes, yes (luc with winter clothes
+and summer clothes). But we have no requirements that these attributes are expressed.
+So, if we have just "luc in boston" as a characterization, the constraint makes sense.
+
+  > 
+  > I believe this consideration is not required and adds a layer of complexity.
+  > 
+  > 5. A characterization interval may collapse into a single instant.
+  > 
+  > Issue: Are we referring to time values. We seem to be using terms like
+  > "characterization interval", "continuous interval", "single instant"
+  > etc. as surrogates for time. I suggest that we explicitly use "time"
+  > if all these other terms are not distinguishable from time.  
+
+Time is a can of worms, since we can have multiple clocks, not necessarily synchronised.
+
+That's why the whole model is event based.
+