Primer Introduction to GraphDB

compared with
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on Aug 21, 2014 17:22.

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The pre-defined rule-sets are layered such that each one extends the preceding one. The following list is ordered by increasing expressivity:
* {{empty}}: *empty*: no reasoning, i.e. GraphDB operates as a plain RDF store;
* {{rdfs}}: *rdfs*: supports standard RDFS semantics;
* {{owl-horst}}: *owl-horst*: OWL dialect close to OWL Horst; the differences are discussed below;
* {{owl-max}}: *owl-max*: a combination of most of OWL-Lite with RDFS;
* {{owl2-rl}}: *owl2-rl*: Fully conformant OWL2 RL profile \[44\] except for D-Entailment, i.e. reasoning about data types.

h2. Custom Rule-Sets

With the *owl-max* rule-set GraphDB supports the following semantics:
* full RDFS semantics without constraints or limitations, apart from the entailments related to typed literals (known as D-entailment). For instance, meta-classes (and any arbitrary mixture of class, property, and individual) can be combined with the supported OWL semantics
* most of OWL-Lite
* all of OWL DLP

The differences between OWL Horst \[37\], Horst \[37\], and the OWL dialects supported by GraphDB (*owl-horst* and *owl-max*) can be summarizsed as follows:
* GraphDB does not provide the extended support for typed literals, introduced with the D*-entailment extension of the RDFS semantics. Although such support is conceptually clear and easy to implement, it is our understanding that the performance penalty is too high for most applications. One can easily implement the rules defined for this purpose by ter Horst and add them to a custom rule-set;
* There are no inconsistency rules by default;
* A few more OWL primitives are supported by GraphDB (rule-set *owl-max*). These are listed in the GraphDB User Guides;
Inference using *owl-horst* is of a lesser complexity compared to other formalisms that combine DL formalisms with rules. In addition, it puts no constraints with respect to meta-modelling.

The correctness of the support for OWL semantics (for those primitives which that are supported) is checked against the normative Positive\- and Negative-entailment OWL test cases \[7\]. cases \[7\]. These tests are provided in the GraphDB distribution and documented in the GraphDB user guides.