No Subject

(define foobar (list 'a))
(set-cdr! foobar foobar)
(test #t equal? foobar foobar)	; (equal? foobar foobar) should return #t

Also, does the sentence

     `Equal?' may fail to terminate if its arguments are circular data
     structures.

allow an implementation to punt whenever a circular data structure is
encountered?  Would the following code not be required to terminate?

(define foobar (list 'a))
(set-cdr! foobar foobar)
(equal? foobar '(a))