or quite a while, but Kauffman's work
will give you a taste of what a semantics for infinite and/or
re-entrant logical expressions would have to be like.  These
issues come up in the branch of topology that studies knots,
and they provide an intuitive foundation for the study of
so-called &quot;non-well-founded set theory&quot; that was already
underway twenty years before Peter Aczel's book came out,
though of course one can trace the dimmer beginnings of
the subject way back before either one of these sou