Re: Wikidata vs DBpedia

[A. Soroka]

This would be a much better question for either the Wikidata mailing list [1] 
or the DBpedia support system [2].

---
A. Soroka
The University of Virginia Library

[1] https://lists.wikimedia.org/mailman/listinfo/wikidata
[2] http://wiki.dbpedia.org/support

> On Mar 19, 2017, at 11:36 AM, kumar rohit  wrote:
> 
> I am sorry if it is slightly off topic.
> 
> How Wikidata differs from DBpedia, in terms of building semantic web
> applications. Wikidata, as I studied as, is a knowledge base which every
> one can edit? How it differs then from Wikipedia?
> 
> DBpedia extracts structured data from wikipedia infoboxes and publishes it
> as rdf.
> 
> If we need Berlin population, we get it from DBpedia via SPARQL. If we can
> do it, why then we need Berlin resource in Wikidata?
> 
> This question will look strange for some, but I want to understand the
> concept.
> Thank you

Re: [MASSMAIL]Re: about TDB JENA

[A. Soroka]

Just a side note; Jena offers SPARQL 1.1, which includes property paths [1]. In 
some situations, they can be used to do some forms of inference (e.g. some 
kinds of problems involving subsumption) right in your SPARQL queries.

---
A. Soroka
The University of Virginia Library

[1] https://www.w3.org/TR/sparql11-query/#propertypaths

> On Mar 19, 2017, at 2:45 PM, Dave Reynolds  wrote:
> 
> On 19/03/17 15:52, Manuel Enrique Puebla Martinez wrote:
>> 
>> I consider that I did not know how to explain correctly in my previous 
>> email, I repeat the two questions:
>> 
>> 
>> 1) I read the page https://jena.apache.org/documentation/tdb/assembler.html, 
>> I do not think it is what I need.
>> 
>>   I work with large OWL2 ontologies from the OWLAPI framework, generated 
>> automatically. With thousands of individuals and more than 13 million 
>> property assertions (data and objects). As one may assume, one of the 
>> limitations I have is that OWLAPI itself can not manage these large 
>> ontologies, that is, because OWLAPI loads the whole owl file into RAM. Not 
>> to dream that some classical reasoner (Pellet, Hermit, etc.) can infer new 
>> knowledge about these great ontologies.
>> 
>> Once explained the problem I have, comes the question: Does JENA solve this 
>> test ?, ie with JENA and TDB I can generate my great ontologies in OWL2 ?, 
>> With JENA and TDB I can use a reasoner to infer new implicit knowledge 
>> (unstated) on my big ontologies?
>> 
>> I do not think JENA will be able to solve this problem, it would be a 
>> pleasant surprise for me. Unfortunately so far I had not read about TDB and 
>> the potentialities of JENA in external memory.
> 
> Indeed Jena does not offer fully scalable reasoning, all inference is done in 
> memory.
> 
> That said 13 million assertions is not *that* enormous, the cost of inference 
> depends on the complexity of the ontology as much its scale. So 13m triples 
> with some simple domain/range inferences might work in memory.
> 
> TDB storage itself scales just fine and querying does not load all the data 
> into memory. So if you don't actually need inference, or only need simple 
> inference that can be usefully expressed as part of the SPARQL query then you 
> are fine.
> 
> Dave
> 

Re: [MASSMAIL]Re: about TDB JENA

[Manuel Enrique Puebla Martinez]

I consider that I did not know how to explain correctly in my previous email, I 
repeat the two questions:


1) I read the page https://jena.apache.org/documentation/tdb/assembler.html, I 
do not think it is what I need.

   I work with large OWL2 ontologies from the OWLAPI framework, generated 
automatically. With thousands of individuals and more than 13 million property 
assertions (data and objects). As one may assume, one of the limitations I have 
is that OWLAPI itself can not manage these large ontologies, that is, because 
OWLAPI loads the whole owl file into RAM. Not to dream that some classical 
reasoner (Pellet, Hermit, etc.) can infer new knowledge about these great 
ontologies.

Once explained the problem I have, comes the question: Does JENA solve this 
test ?, ie with JENA and TDB I can generate my great ontologies in OWL2 ?, With 
JENA and TDB I can use a reasoner to infer new implicit knowledge (unstated) on 
my big ontologies?

I do not think JENA will be able to solve this problem, it would be a pleasant 
surprise for me. Unfortunately so far I had not read about TDB and the 
potentialities of JENA in external memory.

Best Regards, Manuel Puebla.


- Mensaje original -
De: "Lorenz B." 
Para: users@jena.apache.org
Enviados: Domingo, 19 de Marzo 2017 3:52:30
Asunto: [MASSMAIL]Re: about TDB JENA


> Is it possible to use some reasoner with RDF data, managed from TDB? 
Yes, see [1]
>
> Is it possible to manage an ontology in OWL2 from TDB? 
What means "manage"? In general you can load and query any RDF data into
TDB. The serialization of an OWL ontology can be any RDF format.
Obviously, querying OWL constructs via SPARQL can become weird because
an OWL axiom/class expression can consists of more than one RDF triple.

[1] https://jena.apache.org/documentation/tdb/assembler.html

-- 
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org - semantic web research center

La @universidad_uci es Fidel. Los jóvenes no fallaremos.
#HastaSiempreComandante
#HastalaVictoriaSiempre

Wikidata vs DBpedia

[kumar rohit]

I am sorry if it is slightly off topic.

How Wikidata differs from DBpedia, in terms of building semantic web
applications. Wikidata, as I studied as, is a knowledge base which every
one can edit? How it differs then from Wikipedia?

DBpedia extracts structured data from wikipedia infoboxes and publishes it
as rdf.

If we need Berlin population, we get it from DBpedia via SPARQL. If we can
do it, why then we need Berlin resource in Wikidata?

This question will look strange for some, but I want to understand the
concept.
Thank you

Re: about TDB JENA

[Lorenz B.]

> Is it possible to use some reasoner with RDF data, managed from TDB? 
Yes, see [1]
>
> Is it possible to manage an ontology in OWL2 from TDB? 
What means "manage"? In general you can load and query any RDF data into
TDB. The serialization of an OWL ontology can be any RDF format.
Obviously, querying OWL constructs via SPARQL can become weird because
an OWL axiom/class expression can consists of more than one RDF triple.

[1] https://jena.apache.org/documentation/tdb/assembler.html

-- 
Lorenz Bühmann
AKSW group, University of Leipzig
Group: http://aksw.org - semantic web research center