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Semantics of rule implication in RIF-FLD

From: Carlos Damásio <cd@di.fct.unl.pt>
Date: Wed, 9 Sep 2009 17:40:40 +0100
Message-Id: <CB5890BA-BE7F-46C9-930C-6063CC46909B@di.fct.unl.pt>
To: public-rif-comments@w3.org
Dear all,

The semantics of the several connectives in FLD-RIF is many-valued,  
with the single exception of the rule implication symbol.
The rule implication symbol has only two possible values, t and f, the  
top and bottom of the lattice of truth-values.
For instance, this prevents the definition of fuzzy logic dialects of  
RIF without introducing new implication connectives.

I suggest that that the rule implication symbol semantics to be  
generalized in the following way:

Rule implication:
TValI(head :- body) = t, IFF TValI(head) ≥t TValI(body).
TValI(head :- body) < t   otherwise.

This has nice theoretical properties, namely the existence of minimal  
model for every definite Horn program.
This will not affect the notion of model, and would be much more  
general.

Disclaimer:
I've tried to browse the mail archives to see if there was any  
discussion about this, and could not find it.
I don't discuss here the issue of equality, since I am not an expert  
on the subject.

Best regards,

Carlos
Received on Wednesday, 9 September 2009 16:41:13 GMT

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