- From: Markus Krötzsch <markus.kroetzsch@cs.ox.ac.uk>
- Date: Mon, 18 Jul 2011 11:09:17 +0100
- To: Cristiano Longo <longo@dmi.unict.it>
- CC: semantic-web@w3.org
On 18/07/11 10:48, Cristiano Longo wrote: > On 18/07/2011 11:24, Markus Krötzsch wrote: >> On 18/07/11 08:27, Cristiano Longo wrote: >>> Morning all, >>> in the far future I planned to implement a description logic reasoner. >>> May you give me some hints or pointers about the pratical (I yet know >>> the algorithm) for implementing such a reasoner? >> >> Dear Christian, >> >> description logics come in various flavours to match different >> application areas. These different logics also match different >> profiles of OWL: OWL EL, OWL QL, OWL RL, and OWL DL (there is also OWL >> Full but its semantics is not description logics based though both are >> compatible to some extent). >> >> EL, QL, RL are more lightweight for better scalability (for example >> OWL RL has been implemented in distributed settings with billions of >> assertions; and EL has been used to classify ontologies with hundreds >> of thousands of classes in a few seconds; QL is meant for >> ontology-based data access to large databases). OWL DL provides the >> full modelling support of all DL features that OWL has. Lightweight >> languages are genermayally easier to implement but any efficient >> implementation will need a lot of engineering. Just implementing an >> algorithm from a research paper will not lead to good results. >> >> So before you can start, you really need to decide which description >> logic/OWL profile you want to support. This is closely related to >> another important questions: why do you want to implement your own >> tool instead of just using an existing one? >> >> Regards >> >> Markus >> > Since I discovered a description logic in which the consistency problem > in NP-complete (cf. [1]), and I wander if this teoretical property is > relevant in the real world, considering that non-deterministic > computations cannot take place with the hardware that is actually > available. There are already a number of DLs where consistency checking is polynomial. So an NP-complete logic would be somewhere in between the tractable and the highly expressive. Since you have a new unusual semantics for DLs, you will probably have to invent new algorithms too. Markus > > [1] Domenico Cantone, Cristiano Longo, and Antonio Pisasale. Comparing > Description Logics > with Multi-level Syllogistics: the Description Logic DL <MLSS^{×}_{2,m}> > . In 6th Workshop on > Semantic Web Applications and Perspectives (SWAP), 2010. > > -- Dr. Markus Krötzsch Department of Computer Science, University of Oxford Room 306, Parks Road, OX1 3QD Oxford, United Kingdom +44 (0)1865 283529 http://korrekt.org/
Received on Monday, 18 July 2011 10:09:53 UTC