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Re: Booleans as the degenerate case of variable binding results

From: Simon Raboczi <raboczi@tucanatech.com>
Date: Tue, 22 Jun 2004 12:01:03 -0400
Message-Id: <5CAA79B2-C465-11D8-A9DC-000A95C5686E@tucanatech.com>
To: public-rdf-dawg@w3.org


On 22/06/2004, at 10:51, Pat Hayes wrote:

>>> Or, for example, I don't care about the values of foaf:knows 
>>> predicates, I
>>> just want to know whether some FOAF resource contains more than 8 of
>>> them.
>>
>> I think this is an entirely different kind of query.  Rather than 
>> "Can this query be satisfied? I don't care about the particular 
>> variable bindings required to satisfy it.", it's "Calculate a 
>> particular variable binding ?x = (count > 8) whose value just happens 
>> to be a boolean".  In this case you certainly will get an explicit 
>> literal value back, presumably datatyped using XSD. However, it's 
>> just a normal variable binding expression.
>
> Oh dear. I think this is a very bad idea. If we allow variables 
> binding to booleans, the logical framework suddenly gets wildly 
> different. This would take the language well outside the 
> description-logic subset, for example: in fact it takes it outside 
> normal logic altogether.
>
> I'd strongly suggest that we do not have variables ranging over 
> boolean values, or if we do then we loudly ask for comments from other 
> WGs about what the consequences would be.

I assumed a variable binding must at least admit any atomic RDF 
resource, certainly including the datatyped literals 
"true"^^<xsd:boolean> and "false"^^<xsd:boolean>.

Is your objection actually against variables being bound to booleans, 
or would I guess right in thinking it's more about my fast and loose 
use of "count" and ">" to evaluate the value the variable is bound to 
in the example?
Received on Tuesday, 22 June 2004 12:01:42 GMT

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