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Re: [ontolog-forum] blogic iswc keynote

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Christopher Menzel <cmenzel@xxxxxxxx>
Date: Thu, 17 Dec 2009 14:11:32 -0600
Message-id: <3D9336B7-B1C0-4DC2-B652-80CFCD89B074@xxxxxxxx>
On Dec 16, 2009, at 2:27 PM, sowa@xxxxxxxxxxx wrote:
>> RM> Would you have a recommendation for generating representations that's a 
>bit more agile than crocheting?
> Please remember that CLIF and CGIF have been designed as *interchange 
>formats* for an open-ended number of different, but compatible kinds of 
>logics. Every implementation of any one of those subsets *is* an 
>implementation of Common Logic.
> I noticed that in the Q/A section of Pat's talk, somebody said that CL is too 
>expressive -- therefore, it is inefficient.
> But that question is hopelessly confused.    (01)

Agreed.    (02)

> It is based on the assumption that there is *one and only one* method of 
>using or reasoning with any given logic. But that assumption does not hold for 
>*any* natural language, programming language, query language, or, indeed, any 
>version of logic.    (03)

It's not clear to me that that is necessarily being assumed.  Another 
possibility is that the questioner believes that representation languages 
should be *paternalistic* -- that is, they should prevent users from even 
posing questions that are undecidable.  OWL-DL is of course the best known 
language of this sort.  It seems to me that it makes sense to have such 
languages for a certain class of user who is not wise in the ways of 
computational complexity.  However, to take the responsibilities of managing 
complexity from all users of any representation language and instead impose 
this paternalistic restriction on languages in general (not to mention 
interchange formats) makes no sense at all.    (04)

However, I am confused by one thing you wrote:    (05)

> For database queries and constraints, SQL supports full FOL, but even the 
>worst case examples can be evaluated in polynomial time,    (06)

I am probably not understanding the claim, but how is this possible if SQL 
supports full FOL, in which we can easily express problems that can be solved, 
if at all, in at best exponential time?    (07)

-chris    (08)

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