- From: Phillip Lord <phillip.lord@newcastle.ac.uk>
- Date: Thu, 14 Sep 2006 18:26:19 +0100
- To: "Kashyap, Vipul" <VKASHYAP1@PARTNERS.ORG>
- Cc: <semantic-web@w3.org>, <public-semweb-lifesci@w3.org>
>>>>> "KV" == Kashyap, Vipul <VKASHYAP1@PARTNERS.ORG> writes: KV> OWL reasoners support two types of reasoning: KV> 1. ABox reasoning (reasoning about instance data). Scalability KV> here is being achieved here by leveraging relational database KV> technology (which is acknowledged to be scalable) and mapping KV> OWL instance reasoning operations to appropriate SQL queries on KV> the underlying data store. I may be wrong here, but as far as I know the expressivity of OWL-DL, for example, is too different from that of RDBMS for this to work completely. I am not enough of an expert to know if this sort of mapping is possible at all or whether it just cannot be done efficiently. Having said that there is a similar approach, which uses RDBMS. For example, the instance store (http://instancestore.man.ac.uk) which I was briefly involved with (before the backend got to hard for my poor brain!), uses a metaschema backend. Queries are not made by mapping to SQL, but using SQL and reasoner queries together. KV> 2. TBox reasoning scalability is a challenge, especially at the KV> scale of 100s of KV> thousands of classes found in medical ontologies. Would love to KV> hear >From DL experts on this issue. Again, as far as I understand, the complexity of T-Box and A-Box reasoning for logics such as that underlying OWL-DL are not that different (i.e. they are both terrible!), so the issues are much the same. There is not general answer to the size of a T-box you can reason over. If the T-Box is a simple asserted hierarchy, you can build a pretty large ontology (certainly 10's of thousands) and reason over it -- the reasoning in this case being simple. If you start using lots of more complex expressions then you can limit yourself a lot more. This paper for example, managed to get the Gene Ontology and, I think, all of GOA into a DL form and reason over it in a, er, reasonable amount of time. So scalability to 10's of thousands of T-box and 100's of thousands of A-Box's is possible. http://www.cs.man.ac.uk/~dturi/papers/instancestore2.pdf The DL reasoners are much better than they used to be -- in the good old days, when the world was young, you could get most DL reasoners to eat your CPU on a 10 term ontology. Nowadays, it's fairly hard to do this. Phil -- Phillip Lord, Phone: +44 (0) 191 222 7827 Lecturer in Bioinformatics, Email: phillip.lord@newcastle.ac.uk School of Computing Science, http://homepages.cs.ncl.ac.uk/phillip.lord Newcastle University, Claremont Tower, Room 909 NE1 7RU
Received on Thursday, 14 September 2006 17:26:29 UTC