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RE: rdf as a base for other languages

From: Ziv Hellman <ziv@unicorn.com>
Date: Sat, 2 Jun 2001 17:55:38 +0200
Message-ID: <6194CD944604E94EB76F9A1A6D0EDD2310D326@calvin.unicorn.co.il>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: <www-rdf-logic@w3.org>
> Similarly, there is no reason that you cannot have a language that can
> express ground facts, and embed it in a different language 
> that can express
> more.  However, the meaning of this larger language is quite 
> different from
> the meaning of the smaller language.  (Consider how you would handle
> ``facts'' with variables in them---you can't just use the 
> meaning from the
> smaller language, as it has no idea how to interpret the variables.)
> 
> Further, even this is different from having a language for expressing
> ground facts (RDF), encoding more-complex constructs in this 
> language, and
> using the ground facts language as the transfer mechanism.  Under this
> scheme, the encoding of the more-complex constructs are still 
> viewed as
> ground facts, and end up becoming part of their meaning, 
> which is not desired.


I am beginning to lose sight of what the terminology "ground facts" is
supposed to mean in this context.

At the risk of being a considered a dreary pedant, I will sketch out
here how I was taught one constructs a logic, and then ask where this
fits into the terms of the debate raging in this interests list:

a.  Determine a group of "logical" symbols that are "reserved" and
assumed to be a part of any language that one will define and use --
this is where connectives, quantifiers, modal operators, etc. are
declared, perhaps also variables
b. Determine that a language may contain "non-logical" symbols that play
the roles of relations, or functions, or constants etc.
c. Determine rules for deciding what constitutes a well-formed statement
built out of these logical and non-logical symbols
d. At this point, either build a proof theory or a model theory or both.
For a proof theory, declare logical axioms and rules of inference that
enable one, given certain statements as assumed, to infer other
statements as conclusions. For a model theory, one needs to explain how
and when statements in the language are to be considered "satisfied" in
possible worlds or structures or models, etc. 

What are "ground facts" this picture? Where in this picture does RDF fit
in? Where would another language "built atop RDF" fit in? Or is all this
irrelevant to the debate?


Cheers,

Ziv
Received on Saturday, 2 June 2001 10:56:34 GMT

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