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RE: A triple is not unique.

From: Bill dehOra <BdehOra@interx.com>
Date: Mon, 20 Nov 2000 15:22:39 -0000
Message-ID: <DD70D605CB99D411B13600508BDE6F2E081EE6@NTLONDON_01>
To: RDF-IG <www-rdf-interest@w3.org>
Cc: Seth Russell <seth@robustai.net>, "'Jonas Liljegren'" <jonas@rit.se>, Dan Brickley <danbri@w3.org>

> > We have a name for this problem on the Issue Tracking page:
> > http://www.w3.org/2000/03/rdf-tracking/#rdfms-identity-of-statements
> 
> 
> The answer to this question influence the way we can say things about
> reified statements.  As an example (don't know anything about the
> dates.. :-)

I don't think it's that simple (unless Statement is a subtype of Resource).
Consider where R1 and R2 are resources, not statements, and very probably
anonymous (which I assume to mean model dependent):
 
> Model 1:
> 
>  S1: god notplayswith dice
>  S2: S1 statedBy einstein
>  S3: S1 statedAt 1950-04-10

or:

S1: god notplayswith dice
S2: R1 statedBy einstein
S3: R1 statedAt 1950-04-10
S2': R1 sub god
S2'': R1 pred notplayswith
S2''': R1 obj dice


> Model 2:
> 
>  S1: god notplayswith dice
>  S2: S1 statedBy jonas
>  S3: S1 statedAt 2000-11-17

or:

S01: god notplayswith dice
S02: R2 statedBy jonas
S03: R2 statedAt 2000-11-17
S02': R2 sub god
S02'': R2 pred notplayswith
S02''': R2 obj dice

> Combined:
> 
>  S1: god notplayswith dice
>  S2: S1 statedBy einstein
>  S3: S1 statedBy jonas
>  S4: S1 statedAt 1950-04-10
>  S5: S1 statedAt 2000-11-17

or:

S1: god notplayswith dice
S2: R1 statedBy einstein
S3: R1 statedAt 1950-04-10
S2': R1 sub god
S2'': R1 pred notplayswith
S2'': R1 obj dice
S01: god notplayswith dice
S02: R2 statedBy jonas
S03: R2 statedAt 2000-11-17
S02': R2 sub god
S02'': R2 pred notplayswith
S02'': R2 obj dice

I feel safe in making the assumption that two statements with equivalent
resources are equivalent. So I can merge S1 and S01:

S1S01: god notplayswith dice
S2: R1 statedBy einstein
S3: R1 statedAt 1950-04-10
S2': R1 sub god
S2'': R1 pred notplayswith
S2'': R1 obj dice
S02: R2 statedBy jonas
S03: R2 statedAt 2000-11-17
S02': R2 sub god
S02'': R2 pred notplayswith
S02'': R2 obj dice

But that's about it. I can't unify the two reifications the same way unless
there's another assumption I can make about anonymous resources being
equivalent, which is very probably a bad idea. And note that without these
unifications, we can't infer that jonas and einstein are reifiying the same
statement. But maybe I can have rules specific to the sub, pred and obj
properties. If statements with these properties as predicates have the same
object they're equivalent so replace the subjects with a new model dependent
resource (call it Rx). So:

S1S01: god notplayswith dice
S2: Rx statedBy einstein
S02: Rx statedBy jonas
S3: Rx statedAt 1950-04-10
S03: Rx statedAt 2000-11-17
S2'S02': Rx sub god
S2''S02'': Rx pred notplayswith
S2'''S02'': Rx obj dice


-Bill de hÓra
Received on Monday, 20 November 2000 10:23:23 GMT

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