BEGIN:(Clocksin & Mellish 2003:254)
Finally, a note about how Prolog matching sometimes differs from the
unification used in Resolution. Most Prolog systems will allow you to
satisfy goals like:
equal(X, X).
?- equal(foo(Y), Y).
that is, they will allow you to match a term against an uninstantiated
subterm of itself. In this example, foo(Y) is matched against Y,
which appears within it. As a result, Y will stand for foo(Y), which is
foo(foo(Y)) (because of what Y stands for), which is foo(foo(foo(Y))),
and so on. So Y ends up standing for some kind of infinite structure.
END:(Clocksin & Mellish 2003:254)
Not really. I actually refer to infinitely recursive structures
that can only be expressed in Prolog and my own Minimal Type Theory.
https://www.researchgate.net/publication/331859461_Minimal_Type_Theory_YACC_BNF
LP := ~True(LP) specifies ~True(~True(~True(~True(...))))
ZFC prevents the same thing with its redefinition of a {set}.
This seems to be a key precedent where undecidability was
eliminated by correcting the incoherent definition of terms.
> You really should know class/set distinction, about a theory with one relation,
> called elt or element-of, membership, vis-a-vis the class' relation of sethood, or contains,
> it's still only one relation, but either way has that there are multiplicities.
>
> So, "singularity theory", is about singularities like "division by zero",
> "non-principal roots", singularities are multiplicities, "infinity".
>
> So, regularity, well-foundedness, is a property of some sets, naively.
>
> There are other notions of the regular and rulial, like the well-ordering principle.
>
> The well-foundedness and well-ordering not being exactly the same,
> makes for that it's pragmatic for axiomatic set theory and descriptive set theory,
> to stipulate via fiat one fact, which is that there's a well-founded inductive set,
> Axiom of Infinity, though that free comprehension simply arrives at their
> being multiplicities and somehow, "infra-consistent", the objects that exist,
> with respect to their singularities and principal branches variously, about
> why there are singularities in set theory, in singularity theory, which is multiplicity theory.
>
> And it seemed so nice, ....
>