Re: model theory and literals

From: Peter F. Patel-Schneider (
Date: 10/10/01

From: Pat Hayes <>
Subject: model theory and literals
Date: Wed, 10 Oct 2001 12:36:24 -0500

> Peter, after my mini-epiphany during the telecon yesterday, I had an 
> even better one :-). I think that there is a very tiny, if 
> unconventional, change to the RDF MT which will allow it to 
> accommodate smoothly to your (or anyone else's) proposed treatment of 
> literals: simply say (with some explanatory prose :-) that the XL 
> mapping is a fixed mapping from literal TOKENS to literal values. 
> That is, it allows one occurrence of <whatever>05</whatever> to 
> denote an integer and another one to denote a string, just as long as 
> they each denote the same thing in every interpretation. 

Hmm.  Interesting, sneaky, and underhanded!  I like it.

Well, actually, I don't think that it works.  

> This allows 
> both the case where every literal is simply a string which denotes 
> itself, and it also allows the extreme other case where an elaborate 
> external datatyping process assigns special values in all sorts of 
> ways. However, it does insist that each literal label token has a 
> fixed interpretation; it doesn't tolerate ambiguity of any 
> *particular* literal label. I don't want to allow that kind of 
> ambiguity.

See below.

> This will leave entirely mysterious how anyone or anything could 
> determine what the actual denotation of any particular literal token 
> actually is, of course. That is assumed to be done somehow, but is 
> outside the scope of the MT itself.
> With this change in wording, the actual equations can remain as they are.
> Would that be sufficient flexibility for you, along with allowing IR 
> to consist of both resources and literal values, so that rdfs:Literal 
> doesn't force literal values to be resources?

The problem is that I want (for what I consider to be good reasons, see my
posting to www-rdf-comments) to be able to have that

	John age 05 .

has several models, some which have (this) 05 be an integer and some which
have it be a string.

> Pat

My current thinking is that nodes with literal labels are treated much like
nodes with no labels, except that their interpretation is restricted by XL.


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