Re: Blank nodes must DIE! [ was Re: Blank nodes semantics - existential variables?]

On 7/8/2020 9:39 PM, Patrick J Hayes wrote:
> 
> 
>> On Jul 8, 2020, at 1:30 PM, Nicolas Chauvat <nicolas.chauvat@logilab.fr> wrote:
>>
>> On Wed, Jul 08, 2020 at 11:54:16AM -0400, Thomas Passin wrote:
>>> Here's what I am thinking of, and I'll talk about points, since that was the
>>> ...
>>> Or put another way, just because the same literal value is assigned to two
>>> nodes does not make them the same.  Is that literal value itself the "same"
>>> for both?  In some software it might be - if it's been memoized, for example
>>> - but that's normally an implementation detail, not something fundamental.
>>
>> When I say that (1,2) is a true value, aka an immutable struct, your
>> answer is that two (1,2) values are not the same because, taking into
>> account the open world assumption, they could have a third dimension
>> (or some other attribute).
>>
>> You write "the same literal value is assigned to two nodes, does not
>> make them the same”.
> 
> Um.. with one plausible interpretation, that is wrong. (RDF does not have the notions of ‘assignment’, and ’same’ is ambiguous, but ploughing ahead…) Lets use owl:sameAs to attach a literal value to a URI:
> 
> ex:this owl:sameAs “17”^^xsd:integer .
> ex:that owl:sameAs “17”^^xsd:integer .
> 
> and now ask, are this and that the same?:

Right -the owl:sameAs relation (or some other relation with a similar 
meaning) makes it clear that you can rule out interpetations in which it 
was not so.  Otherwise those interpretations could still be compatible 
with the RDF graph.

I'm supposing that there would be more (many more) graphs that do not 
this restriction than that do. Equivalently, there are probably many 
cases where there are different nodes with literal values that happen to 
have the literal value of  “17”^^xsd:integer, and probably only a "few" 
of them are really intended to be the same node.

Maybe that is a vacuous notion because how would one enumerate all the 
interpretations and graphs to verify the claim ...

TomP

Received on Thursday, 9 July 2020 02:16:44 UTC