Jens Lehmann wrote:
>
> Hello,
>
> Kingsley Idehen wrote:
>> Jens Lehmann wrote:
>>>
>>
>> We are completing a similar test here based on my response earlier
>> this week.
>
> Was the test successful?
>
>> I assume you are trying to load the Yago Class Hierarchy? If so, let
>> us finish our investigation and then we will have a proper report :-)
>
> Yago was already loaded into our local Virtuoso instance at that time.
> Then we used rdfs_rule_set ('http://dbpedia.org',
> 'http://dbpedia.org'); or something similar to enable inferencing,
> which returned an out of memory error after a couple of hours.
>
> Kind regards,
>
> Jens
>
>
Jens,
The current version of Virtuoso has a number of suboptimal issues
relating to the initial Inference implementation that includes:
Memory management issues (as you encountered) emanating from heuristics
for traversing OWL class hierarchies (tree) when processing inference
rules. With the fix we now start from the class hierarchy roots and
traverse to the bottom of the OWL tree instead of every superclass using
a dynamic hash , which grew exponentially. Thus, Virtuoso now uses a
list (array of 100 preallocated elements) for a branch of the OWL tree,
and when this fills up it extends dynamically. Also, it now checks for
subclass definition presence in inference rules based on a hash instead
of a linked list.
A new Virtuoso release is imminent, the only hold up right now is the
completion of Model Providers for: Jena, Redland, and more than likely
Sesame. The pervasiveness of these frameworks has encouraged us to make
Virtuoso play as well as can be in each of these realms. The goal is to
make Virtuoso's performance and scalability features easier for these
communities to exploit.
Anyway, the live DBpedia has been updated.
Important Note: The injection of Yago Class Hierarchy rules into the
current data set is an enhancement to the current DBpedia release.
Behind the scenes, there is work underway, aimed at providing an
enhanced Class Hierarchy and associated inference rules using UMBEL
(which meshes Yago and OpenCyc).
Once the next Virtuoso release out, those of you with local
installation will be able to do the following via iSQL or the Virtuoso
Conductor:
--- Load Class Hierarchy into a Named Graph
select ttlp_mt (file_to_string_output ('yago-class-hierarchy_en.nt'),
'', 'http://dbpedia.org/resource/classes/yago#');
-- Create an Inference Rule that references the Yago Class Hierarchy
Named Graph
rdfs_rule_set ('http://dbpedia.org/resource/inference/rules/yago#',
'http://dbpedia.org/resource/classes/yago#');
-- Test Queries (* Here I've taken the Owlgres demos and applied them
to DBpedia. This also makes for easy juxtaposition of Owlgres [1] and
Virtuoso features with regards to OWL based Reasoning*)
-- Collection of SPASQL (SPARQL executed within Virtuoso's SQL
processor) based verification queries
--
-- Query for the "The Lord of the Rings" which is a "Book" as explicitly
claimed in the DBpedia data set (instance data)
SPARQL
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s
FROM <http://dbpedia.org>
WHERE {
?s a yago:Book106410904 .
?s dbpedia:name "The Lord of the Rings"@en .
};
-- Query aimed at Books via query scoped to the "Publication" class of
which it is a subclass in the Yago Hierarchy
SPARQL
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name "The Lord of the Rings"@en .
};
-- # Testing Virtuoso's Full Text Index extension: bif:contains
SPARQL
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name ?n .
?n bif:contains 'Lord and Rings'
};
-- Retrieve all individuals instances of the Book Class
SPARQL
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Book106410904 .
?s dbpedia:name ?n .
};
-- Retrieve all individuals instances of Publication Class which should
include all Books.
SPARQL
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name ?n .
};
Pure SPARQL Examples:
- Query aimed at Books via query scoped to the "Publication" class of
which it is a subclass in the Yago Hierarchy
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name "The Lord of the Rings"@en .
}
-- Variant of query with Virtuoso's Full Text Index extension: bif:contains
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name ?n .
?n bif:contains 'Lord and Rings'
}
-- Retrieve all individuals instances of the Book Class
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Book106410904 .
?s dbpedia:name ?n .
}
-- Retrieve all individuals instances of Publication Class which should
include all Books.
define input:inference 'http://dbpedia.org/resource/inference/rules/yago#'
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX dbpedia: <http://dbpedia.org/property/>
PREFIX yago: <http://dbpedia.org/class/yago/>
SELECT ?s ?n
FROM <http://dbpedia.org>
WHERE {
?s a yago:Publication106589574 .
?s dbpedia:name ?n .
}
--
Regards,
Kingsley Idehen Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO
OpenLink Software Web: http://www.openlinksw.com
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