Re: [External] : example showing why rdf:state is essential

Hi Thomas,

Yes, SPARQL1.2 can provide shortcuts to support various combinations of the three different types of tuples that are supported in the two-property approach (that use rdf:asserts and rdf:reifies), as I had outlined originally in [1] and reproduced here with a slightly more elaborate terminology.

Types of tuples :
============
    type [gA: graph-scoped Assertion] => :s :p :o . ==> (asserted, graph-scoped) s-p-o triple
    type [iA: id-scoped Assertion] => :id rdf:asserts <<( :s :p :o )>> . ==> "asserted, id-scoped" id-s-p-o tuple
    type [iR: id-scoped Reification] => :id rdf:reifies <<( :s :p :o )>> . ==> "reified, id-scoped" id-s-p-o tuple

SPARQL pattern extensions: (to allow retrieval of all seven non-empty elements in the power set: [gA], [iA], [iR], [gA | iA], [iA | iR], [gA | iR], [gA | iA | iR] )
=======================
0) [gA] => ?s ?p ?o . # graph-scoped Assertions ==> s-p-o triples only
1) [gA | iA] => ?id ~ ?s ?p ?o . # graph-scoped Assertions UNION id-scoped Assertions ==> s-p-o triples and "asserted" id-s-p-o tuples
2) [gA | iR] => ?id | ?s ?p ?o . # graph-scoped Assertions UNION id-scoped Reifications==> s-p-o triples and "reified" id-s-p-o tuples
3) [gA | iA | iR] => ?id * ?s ?p ?o . # all types of tuples => graph-scoped Assertions UNION id-scoped Assertions UNION id-scoped Reifications

Use FILTER bound(?id)=TRUE to exclude the graph-scoped Assertions (i.e., exclude the s-p-o triples) in choices 1, 2, and 3 above to implement retrieval choices [iA], [iR], [iA | iR], respectively.

Here are some sample queries and results (for the data shown in [2]):
=========================
- select (count(?for) as ?count) where { ?id ~ :Bob :workedFor ?for } .
    RESULT: [ ?count = 3 ]
- select (count(?for) as ?count) where { ?id * :Bob :workedFor ?for } .
    RESULT: [ ?count = 4 ]

Thanks,
Souri.

[1] https://lists.w3.org/Archives/Public/public-rdf-star-wg/2024Aug/0053.html
[2] https://lists.w3.org/Archives/Public/public-rdf-star-wg/2024Aug/0104.html
________________________________
From: Thomas Lörtsch <tl@rat.io>
Sent: Saturday, August 17, 2024 4:28 AM
To: public-rdf-star-wg@w3.org <public-rdf-star-wg@w3.org>; Souripriya Das <souripriya.das@oracle.com>; James Anderson <anderson.james.1955@gmail.com>; RDF-star Working Group <public-rdf-star-wg@w3.org>
Subject: Re: [External] : example showing why rdf:state is essential

Hi Souri,

IMO the answer should be 3, because the whole point of this rdfs:states thing is to go beyond what reification (and rdf:reifies or whatever its name will end up to be) can provide, and interpret triple terms in the rdfs:range of rdfs:states as actually stated. That sure is beyond simple RDF entailment, but IIUC SPARQL-star can do it.

Therefore, wouldn't it be more practical to define that any query runs over standard triples AND also triple terms that are the object of an rdfs:states relation? (maybe not always always, but triggered by a keyword like WITH QUALIFIED)? Wouldn't that perfectly capture the intention that triple terms in the rdfs:range of rdfs:states are assumed/expected to be true in the graph? Maybe call this SPARQL-star entailment? IIUC this is the approach taken in the original RDF* proposal, so given that RDF* had multiple implementations, including pretty high profile ones, it should be practical, right?

Best,
Thomas


Am 17. August 2024 05:53:01 MESZ schrieb Souripriya Das <souripriya.das@oracle.com>:
Hi James,

>> 1) Two-property example:
>>
>> # mapping from relational data: one-to-one, using RDF1.2-supported "asserted under id" tuples (that use the rdf:asserts property)
>> :stint1 rdf:asserts <<( :Bob :workedFor :A )>> ; :start 1980 ; :end 1990 .
>> :stint2 rdf:asserts <<( :Bob :workedFor :B )>> ; :start 1990 ; :end 2000 .
>> :stint3 rdf:asserts <<( :Bob :workedFor :A )>> ; :start 2000 ; :end 2010 .
>>
>> # adding some unreliable info using RDF1.2-supported "reified under id" tuple (that use the rdf:reifies property)
>> :stint4 rdf:reifies <<( :Bob :workedFor :B )>> ; :start 2010 ; :end 2020 .
> under this proposal, what would be the result of the following sparql query

> select (count (?for) as ?count)
> where { :Bob :workedFor ?for }

> were it applied to a graph which included those four statements?

The result will be [ ?count = 0 ]. This is because no s-p-o triple was loaded and due to the "no side-effect" principle of this approach, no such s-p-o triple was automatically generated. In general, asserted id-s-p-o tuples do not have the side-effect of generating the corresponding s-p-o triples.

Here are some related variations of the above query that will produce different results:
- select (count(?for) as ?count) where { ?id rdf:asserts <<( :Bob :workedFor ?for )>> } .
    RESULT: [ ?count = 3 ]
- select (count(?for) as ?count) where { ?id rdf:reifies <<( :Bob :workedFor ?for )>> } .
    RESULT: [ ?count = 1 ]
- select (count(?for) as ?count) where { ?id ?p <<( :Bob :workedFor ?for )>> . FILTER( ?p IN (rdf:asserts, rdf:reifies) ) } .
    RESULT: [ ?count = 4 ]

Thanks,
Souri.

________________________________
From: James Anderson <anderson.james.1955@gmail.com>
Sent: Friday, August 16, 2024 8:43 PM
To: RDF-star Working Group <public-rdf-star-wg@w3.org>
Subject: Re: [External] : example showing why rdf:state is essential

good morning;

> On 16. Aug 2024, at 23:15, Souripriya Das <souripriya.das@oracle.com> wrote:
>
> ...
>
> 1) Two-property example:
>
> # mapping from relational data: one-to-one, using RDF1.2-supported "asserted under id" tuples (that use the rdf:asserts property)
> :stint1 rdf:asserts <<( :Bob :workedFor :A )>> ; :start 1980 ; :end 1990 .
> :stint2 rdf:asserts <<( :Bob :workedFor :B )>> ; :start 1990 ; :end 2000 .
> :stint3 rdf:asserts <<( :Bob :workedFor :A )>> ; :start 2000 ; :end 2010 .
>
> # adding some unreliable info using RDF1.2-supported "reified under id" tuple (that use the rdf:reifies property)
> :stint4 rdf:reifies <<( :Bob :workedFor :B )>> ; :start 2010 ; :end 2020 .

under this proposal, what would be the result of the following sparql query

select (count (?for) as ?count)
where { :Bob :workedFor ?for }

were it applied to a graph which included those four statements?

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