Re: technical detail feedback on OWL Rules: truth value for empty consequent

From: pat hayes (
Date: 11/04/03

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    >Hi folks,
    >TimBL pointed out today that if the rule consequent in OWL Rules is 
    >a conjunction of zero or more class atoms,
    >then when empty (i.e., zero case) it should logically be True, not 
    >False, since an empty conjunction is True.
    There seems to be little utility in having the consequent being a 
    conjunction. I tend to think of the logical form of a rule as being a 
    clause, so that the antecedent is a conjunction but the consequent is 
    naturally a disjunction. Hence the appeal of Horn clauses, of course.
    >I'm not sure what we want to do about this.  The floor is open...
    Remove the condition that a consequent is a conjunction. Its never a 
    conjunction, except as syntactic sugar for a conjunction of rules 
    each with a singleton-disjunction consequent.
    >Prof. Benjamin Grosof
    >Web Technologies for E-Commerce, Business Policies, E-Contracting, 
    >Rules, XML, Agents, Semantic Web Services
    >MIT Sloan School of Management, Information Technology group
    > or
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