Re: Universal grammar



In article <874pttiv7x.fsf@xxxxxx>, Markus Triska <triska@xxxxxx> wrote:

where A(x) is a predicate. These are combined with axioms (medelson, p.57):
(K4) all x A(x) => A(t) if t is a term free for x in A.
(Gen) A |- all x A(x). (Generalization)

(Re-)introducing universal quantifiers is unnecsseary if you know that
you'll be using (a variant of) resolution (in Prolog: SLD-resolution),
since they are dropped again anyways after skolemization.

I decided to avoid such simplifications for various reasons. One is to
preserve (human intended) structure of formulas. Another, Skolem normal
form only applies to first order theories, and the existential quantifiers
appear before the universal quantifiers. In a axiomatic set theory, the
rewriting involves the axiom of choice.

And, as for Selected Literal Definite clause resolution, the Wikipedia
says it only applies to Horn clauses. - My resolution engine does
not operate on Horn clauses at all anymore, but only on the proof trees.

--
Hans Aberg
.



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