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Re: [DTB] What is a dialect?

From: Axel Polleres <axel.polleres@deri.org>
Date: Fri, 10 Apr 2009 14:17:48 +0100
Message-ID: <49DF46FC.6040204@deri.org>
To: Jos de Bruijn <debruijn@inf.unibz.it>
CC: RIF <public-rif-wg@w3.org>
Jos de Bruijn wrote:
> What is a dialect? And what does it mean for a dialect to support a
> datatype?
 >
> This is not defined in DTB, but it is referred to very often. 

Yes, and I firmly believe that a definition of what is a dialect does 
not belong into DTB

It is somewhat defined in FLD (but not spelled out as definition of 
"what is a dialect") in the following sense:

FLD, Section 3.3:
"Semantic structures are always defined with respect to a particular set 
of datatypes, denoted by DTS. In a concrete dialect, DTS always includes 
the datatypes supported by that dialect. All RIF dialects must support 
the primitive datatypes that are listed in Section Datatypes of [RIF-DTB]."

That is a datatype is supported by a (logic) dialect, if it is a member 
of DTS in the semantic structures for that dialect.

> In
> particular, what happens if I use a dialect (e.g., BLD), but use more
> datatypes than are strictly required to be supported by implementations?
> In addition, it is nowhere specified which datatypes are "supported" by
> Core or BLD.

The semantics of BLD is defined in terms of DTS, but indeed the BLD 
document doesn't fix DTS to only those mentioned in DTB, see BLD, 
Section 3.2, it is only said that:

"The effect of datatypes. The set DTS must include the datatypes 
described in Section Primitive Datatypes of [RIF-DTB]. "


In what is quoted above from FLD and BLD, it is implicit that ALL 
dialects must support those DTs in DTB. but it might not be said that 
they do not support more. Still, DTB is not the place to define this, is it?

Apart from supported datatypes, FLD specifies, and DTB relies on this 
(copying the definitions in an appendix, which, re-thinking it, is not 
such a brilliant idea) that a dialect defines a Coherent set of external 
schemas, DTB defines exactly such a set of coherent schemata.


We probably should spell this out in DTB or FLD:

A RIF dialect needs to define:
  - a set of supported symbol spaces
  - a subset of symbol spaces with a special semantics which are the 
supported primitive datatypes
  - a coherent set of external schemata, defining external functions and 
predicates.

Still, even this doesn't define what a dialect IS, does it?
And, does this only apply to logic dialects, does it also apply to PRD?
etc. I have not answer at this point to this and would appreciate 
opinions how to address this in DTB.


Axel


-- 
Dr. Axel Polleres
Digital Enterprise Research Institute, National University of Ireland, 
Galway
email: axel.polleres@deri.org  url: http://www.polleres.net/
Received on Friday, 10 April 2009 13:18:33 GMT

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