|From:||"Adrian Walker" <adriandwalker@xxxxxxxxx>|
|Date:||Thu, 8 Feb 2007 12:20:02 -0500|
Hi John --|
Datalog, for example, is a cleaned up version of the SQL query language with the extension of
allowing recursive definitions.
Well, that's an approximate idea. However, the following would be more accurate:
"datalog+closed world negation allowing some recursive definitions is a cleaned up version of SQL minus aggregations"
Actually, if there is to be a new Wikipedia or other encyclopedia entry on logic for ontologies, it should summarize the ongoing debate between the "closed" and "open" world negationist camps. Almost all uses of databases in our everyday life rely on things like "if it's not in the catalog we don't stock it", "if no flight number to Podunk is in the database, then there is no flight to Podunk", so we should not ignore closed world usage of databases just because the clasical logicians never wrote about it.
Cheers, -- Adrian
PS: There is of course a model theory for stratified datalog plus closed world negation. See e.g.
Backchain Iteration: Towards a Practical Inference Method that is Simple
Enough to be Proved Terminating, Sound and Complete. Journal of Automated Reasoning, 11:1-22.
Internet Business Logic (R)
A Wiki for Executable Open Vocabulary English
Online at www.reengineeringllc.com
Shared use is free
On 2/8/07, John F. Sowa <sowa@xxxxxxxxxxx> wrote:
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