[Fwd: [BLD] problem with definition of entailment]

I spotted a problem with the definition of entailment in the LC document
of BLD. I originally sent the message only to Michael.
It is probably good to archive this issue on the public mailing list, so
that we may track it.


Best, Jos

-------- Original Message --------
Subject: [BLD] problem with definition of entailment
Date: Thu, 21 Aug 2008 17:12:11 +0200
From: Jos de Bruijn <debruijn@inf.unibz.it>
To: Michael Kifer <kifer@cs.sunysb.edu>

Michael,

I found a problem with the definition of entailment in BLD. We want
entailment to be defined for any formula, specifically, the entailed
formula can be an arbitrary condition formula.  However, you state that
if a formula is not a document, then it belongs to a special query
document. Now, the notion of "query document" is not defined.  This is
one problem.
If we assume that the query document is simply a document, then we have
the problem that in BLD documents cannot contain condition formulas;
they can only contain facts and rules.  So, in that case entailment is
not defined for all condition formulas.
I suspect this is an error, so I would suggest to either defined
satisfaction for condition formulas or properly define the notion of
"query document".


Best, Jos
-- 
Jos de Bruijn            debruijn@inf.unibz.it
+390471016224         http://www.debruijn.net/
----------------------------------------------
No one who cannot rejoice in the discovery of
his own mistakes deserves to be called a
scholar.
  - Donald Foster

-- 
                         debruijn@inf.unibz.it

Jos de Bruijn,        http://www.debruijn.net/
----------------------------------------------
One man that has a mind and knows it can
always beat ten men who haven't and don't.
  -- George Bernard Shaw