|From:||"Adrian Walker" <adriandwalker@xxxxxxxxx>|
|Date:||Sat, 10 May 2008 16:04:01 -0400|
Hi John --|
Yes, as you say, an executable "pivot" logic language is most important.
I think we would all agree that such a language has to have a useful model theoretic semantics.
Classical logic is a prime candidate language. Unfortunately, classical logic assigns a meaning to negation that differs from the way databases are actually used. So Common Logic, OMG SBVR, and many other widely discussed language designs -- surprisingly -- don't actually assign relevant meanings for practical use with relational databases. (To see this, note that classical logic reasoning over a current IBM employee database answers the question "Does John_Sowa work for IBM ?" with "Unknown", whereas the answer should be "No" **.)
It is mainly because of this divergence from actual usage that the semantics of Datalog extended with negation-as-failure (NAF) has been widely studied, and has been assigned its own model theoretic semantics. The semantics used inside the Internet Business Logic system  is based on a model theory  for Datalog extended with NAF, with some further extensions for aggregation and other numeric computation.
I believe that where you and I agree is that it's crucial to have an executable English layer between end author-users and the logic. Such a layer captures the intention of an author, so that a user can see what the intention is. Calling this a "semantic layer" would seem to be justifiable.
You and I appear to diverge on where the semantics for the English layer should reside. You advocate an approach based on a grammar of English together with a dictionary defining, once and forever, the meanings of individual words. I advocate a lightweight approach in which words take their meaning from context, because it appears to be less brittle, and better able to support government acronyms, jargon usage, ontological notations [3,4], and so on. The lightweight approach is the one used in .
Your point about avoiding lock-in by supporting a broad version of logic is well taken, so long as the model theoretic semantics is a relevant one. For developers, rather than end-authors,  provides a Service Oriented Architecture endpoint on the Web. Developers can use notations such as in the example .
Cheers, -- Adrian
 Internet Business Logic. A Wiki and SOA Endpoint for Executable Open Vocabulary English over SQL. Online at www.reengineeringllc.com Shared use is free
 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. (This is an early paper, and others have extended the semantics in an upward compatible manner.)
** This can be finagled, but then you are no longer using a clean model theoretic semantics, or you are hacking at the application level.
On Sat, May 10, 2008 at 11:33 AM, John F. Sowa <sowa@xxxxxxxxxxx> wrote:
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