This page is part of the web mail archives of SRFI 38 from before July 7th, 2015. The new archives for SRFI 38 contain all messages, not just those from before July 7th, 2015.
iirc, Al Petrofsky posted an algorithm that detects circularities without also catching sharing. It has higher computational complexity and is harder to implement than detecting all sharing.Numbers are not interesting (in the sense of the (interesting?) subfunction in the reference implementation), because they may have an (eq?) relationship whenever they are (eqv?).
Just to clarify, I was referring to a *different* Al Petrofsky algorithm, not the one you included in this srfi. The one in the srfi does sharing (as you say, some further investigation is needed to check what kind of sharing it detects), the one I'm referring to detects circularities *only*.