[mizar] improper (fwd)

[Josef Urban <urban@ktilinux.ms.mff.cuni.cz>]

---------- Forwarded message ----------
Date: Tue, 4 Jul 2006 12:42:06 -0500
From: Robert Boyer <boyer@cs.utexas.edu>
To: urban@ktilinux.ms.mff.cuni.cz
Subject: improper

That's a good question, but I don't know to answer it.

I think that the distinction between classes and sets is a
bit painful in English because historically set theories
vary as to whether classes exist and how they are related to
sets.  Are all classes sets?  If not, are even some classes
sets?  If not, are there even any classes at all?

To be clear in Kelley-Morse-speak, I would say 'is a member
of U', which might lead one to coin an adjective such as
'Uic', 'Uan', 'Uish', or 'U' (in analogy with Gaelic,
American, Irish, and Zulu).  The last one would be
especially confusing.  If 0 is U, then all is one, no?

Bob