Hi Richard,

Actually what we wanted to develop was comparing text sources, not URIs. The discussion, and your comment, shows that probably we have to regard comparing identifiers in texts and in knowledge bases on an equal level.

I'd modify your example:
1. The word 'Passau' on the train ticket I found refers to a E53 Place X known exactly by the ticket authority. 2. The first DHd conference took place in E53 Place Y , following a knowledge base.
3. X co-refers to Y in my opinion.

If the train ticket is mine, I should have definite knowledge which place it means. Then it would be a simple refers, in my local knowledge.

Generally, a CRM instance is an information object in its own right. We can naively assume, that the maintainer knows what its identifier mean (or knows who knows). Then, we need no discourse
about potential matches, only about "errors".

Well, let's discuss that on Thursday (I hope we'll have enough time).

Best,

Martin

On 1/4/2014 12:00 ??, Richard Light wrote:

I must confess that I have problems with this co-reference framework.

What I would expect us to be developing is a way of making statements that, in someone's opinion, this CRM entity X is (or is not) the same real-world entity as that CRM entity Y. This is what I understand real-world co-referencing exercises do, e.g. aligning person identifiers in BNB with those in VIAF [1], using owl:sameAs or skos:exactMatch relationships. The difference we would bring to current practice is that we would be providing an attribute assignment context which allows us to state who is asserting the co-reference, when they did it, etc., and allowing them to give their reasons. Having "reified" the initial co-reference assertion, it would be possible for others to take issue with it, support it, etc. Have I misunderstood the intention here?

If that is what we are aiming to develop, I would expect the co-reference assignment to be populated by two or more E1 CRM Entities, being the subjects of the co-reference statement. Instead, we have a situation where there is only one E1 CRM Entity, the "co-reference target", with E89 Propositional Objects being said to co-refer to it (or not).

In the example being discussed, I would prefer to say:



Only assertion (3) is a co-reference statement; the other two are simply ways of defining E53 Places by stating their properties, so that the co-reference statement has some meaningful context.

A weakness of the current approach, in my view, is that it "finesses" one of the E1 CRM Entities involved, by only inferring it from an E89 Propositional Object, rather than stating it explicitly. In many real-world cases, the entities to be co-referred will be identified by an E42 Identifier (e.g. a Linked Data URL), which would be disallowed by the current range of P153/P154.

What we currently have, in my view, is actually "reference", rather than "co-reference", i.e. a means of assigning an additional property to a single E1 CRM Entity.

Richard

[1] see e.g. http://bnb.data.bl.uk/doc/person/LightAlanR1950-.rdf

On 01/04/2014 00:27, Øyvind Eide wrote:
On 30. mars 2014, at 21:25, martin wrote:

Dear Oeyvind,

On 29/3/2014 10:13 ??, Øyvind Eide wrote:
It is quite possible that I do not understand what you say about P155. So this 
is my understanding of it:

Co-reference assignment is about making explicit a fact which is assumed by the 
one making the assignment to be true.
Yes.
An example:

I claim that the word "Passau" on my train ticket and the place referred to by "city 
where the first DHd conference took place" both refer to the physical place Passau. If I make 
this statement in an information system, I would say:

E91 Co-Reference Assignment P155 has co-reference target P53 Passau.
(+ the other properties)

The P155 points to the thing in the world to which the person making the 
co-reference assignment believes the references to point to.
Yes. How do I know that the URI (or whatever the range instance of P155 is) 
points to the Passau
I ment when I make this statement? This is why I said,
"The range of P155 can be interpreted as a URI (or whatever identity) used within the 
same knowledge base as the instance of E91. Then, it would correspond to a co-reference 
between some text element and the knowledge base in which we implement the CRM, the 
"local truth".

It means, the Co-Reference statement shares the same reality (my understanding 
of the world )
as the identifier for "Passau" at p155. In other words, I know by sure how to 
relate this identifier to
the City in Bavaria. It could however be, that I refer to a URI for "Passau", 
which has been imported
in my knowledge base, and indeed was used for another Passau in another 
knowledge base which coined the URI. Then, my coref statement would be 
misleading. Indeed, it would be yet another co-reference, but this time to the 
use of a URI within a knowledge base, rather than a word within a text.

All the magic is in your phrase: "The P155 points to the thing in the world". 
Whose world?

Therefore, I'd suggest that P155 must point to an identifier of something the 
person who makes the
co-ref statement has an unambiguous notion of reality about, either a thing in 
the world by use
of an identifier the person "knows" to interpret, or pointing to a hypothetical thing 
"the thing referred in these two texts, whatever it is". In the latter case, it has an 
identity condition based on the text.
In any case, the scope note must make clear what difference is between P155 the 
other links in terms
of knowing. Therefore I proposed a "local shared truth" for P155.

Opinions?
Dear Martin,

I think I understand now. But to make it clear if I do:

in a normal reference situation, for instance (to go back to the situation of 
the example in CRM):

E82 Hans Jæger (the name on the title page of the book) P131 identfies E21 Hans 
Jæger (the historical person)

In that case the problem of reference you talk about does not apply.

But in the situation:

E91 Co-Reference Assignment P155 has co-reference target E21 Hans Jæger (the 
historical person)

the problem does arise.

The difference between the two situations is that in the former (P131) the 
reference is expressed in the model, whereas in the latter (P155) the 
references is expressed in a statement recorded in the model.

Right?

The questions is: do we need to record what the person making the co-reference statement 
believes the propositional objects refer to? The reference from each of them 
will/should/may be recorded in the system throught systems such as the various 
"identifies" properties.


Best,

Øyvind
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