[CL] XML annex: nothings and the ID namespace

[Chris Menzel]

On Tue, Nov 01, 2005 at 01:41:36PM -0600, Pat Hayes wrote:
> There are textbook logics that go both ways on this, I don't agree
> that CL is in a class by itself. I think that among the 20 or so
> textbooks I once read when I was a logic teacher, about a third of
> them did not distinguish variables as a syntactic category.

Hm, are you sure those weren't books on, say, combinatory logic, in
which the notion of a variable simply has no purchase?  I don't know of
any presentation of more-or-less standard predicate logic that does not
distinguish variables from constants.

-chris