Changes by: Xin Yu (xiny at cs.caltech.edu)
Date: 2003-04-14 00:53:33 -0700 (Mon, 14 Apr 2003)
Revision: 4426
Log message:
Defined group monomorphism/epimorphism; Changed the definition of group
isomorphism; And added/proved more properties.
Now everything about groups in CZF is implemented in ITT except the example
of Klein 4-group.
"groupMono_ker2" remains unproved since it requires some esquash equality
elimination.