Note-2-7-rules
ACL2 Version 2.7 Notes on Changes in Rules and Constants
The defcong macro has been slightly changed. The
difference is that the variable generated with suffix -EQUIV will now be
in the same package as the name of the variable from which it is generated,
rather than always belonging to the ACL2 package. Thanks to Hanbing Liu for
suggesting this change. (Note that a couple of books have been modified to
accommodate this change, e.g., books/finite-set-theory/set-theory.)
In Version_2.6, a change was made for rules of class :rewrite
whose conclusion is a term of the form (EQV lhs rhs), where EQV is
=, eq, or eql: the rule was stored as though EQV
were equal. (See note-2-6-rules.) This change has been
extended to rules of class :definition.