In article <23af61c2.0108202033.5c3e91ca@posting.google.com>, Robert Dodier writes:> I (Robert Dodier) wrote: > >>> Consider a less-extreme example, then: let A = "the mayor is tall", >>> B = "the mayor is heavy", and B' = "the mayor is well-dressed". For the >>> sake of argument suppose that truth(B)=truth(B'). Despite the fact that >>> we know that there is some relation between height and weight, the >>> truth value assigned to a compound containing A and B is just the same >>> as what we get by putting B' in the place of B. > > Stephan.Lehmke@cs.uni-dortmund.de (Stephan Lehmke) wrote: > >> Again, i must ask whether the situation would change if two-valued >> logic were employed? > > I'm assuming that these propositions are not definitely true nor false, > so two-valued logic is not applicable here. Let's stick to the topic, > shall we?
You mean there's no way A and B and B' can assume a truth value from {0,1}? That's a peculiar kind of fuzzy logic you're employing. [Some interesting stuff snipped]>> I think we're talking cross purposes here. Logic is not about >> computing truth values, but about drawing conclusions from assertions. > > Well, is it not the case that drawing conclusions, in fuzzy logic, > is accomplished by computing truth values?
In strict sense, no.>> Of course, it is perfectly possible to state the relations between A >> and B it the form of axioms, as I have pointed out before. > > No, this won't help. According to the usual rules of inference in > fuzzy logic, the truth value of a compound is a function of the truth > values of the parts alone, and therefore there is no place to enter > information about relations between the parts.
As I said, inference isn't done by computing truth values.> You can state all the axioms you want; there is no way to enter these > into the usual truth-functional rules.
Please elaborate.> Perhaps you have in mind some > alternate rules -- if so, how do you know your rules take precedence? > More to the point, how would an automated system know which rules > take precedence?
That something is derivable means it is derivable in any way. In principle, all rules have to be tried. regards Stephan -- Stephan Lehmke Stephan.Lehmke@cs.uni-dortmund.de Fachbereich Informatik, LS I Tel. +49 231 755 6434 Universitaet Dortmund FAX 6555 D-44221 Dortmund, Germany