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RE: [BIONT] Teleconference 22nd August, 2006 - All times are US Eastern!

From: Mork, Peter D.S. <pmork@mitre.org>
Date: Tue, 22 Aug 2006 10:13:09 -0400
Message-ID: <224FBC6B814DBD4E9B9E293BE33A10DC01177725@IMCSRV5.MITRE.ORG>
To: "John Barkley" <jbarkley@nist.gov>, "Ivan Herman" <ivan@w3.org>, "Matthias Samwald" <samwald@gmx.at>
Cc: <public-semweb-lifesci@w3.org>

>>just a small datapoint to what you say. Although I essentially agree,
we
>>should not forget that even OWL-Lite requires a Description Logic
>>reasoning engine (if one wants to use reasoning, that is).
>
>I also think we should consider a recommended practice of using OWL
Lite or
>DL where possible (i.e., when the knowledge base can be expressed in
no
>more
>than DL).
>
>With regard to the point "if one wants to use reasoning",
unfortunately,
>those who are only interested in querying must be aware of reasoning.
For
>example, the property "sameAs" is symmetric. Thus, if your knowledge
base
>has "A sameAs B", one would fully expect the query "?x sameAs A" to
return
>"B". However, query engines without reasoners won't. Therefore, one
must
>put
>"A sameAs B" and "B sameAs A" into their knowledge base in order to
get the
>expected results.
>

Entering "A sameAs B" and "B sameAs A" into the knowledge base (to get
the expected results) just means that you are performing
forward-chaining rather than backwards-chaining.  For smaller
knowledge-bases expected to handle a large number of queries,
forward-chaining makes sense.

My point is that pre-computing a result doesn't allow you to avoid
reasoning.  You're just making a trade-off between space and time.
(Note that once you introduce certain constructs forward-chaining may
not be possible because of an undefined fixpoint.)

Peter
Received on Tuesday, 22 August 2006 14:16:39 GMT

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