The full version of this announcement is available.
Covariant deep subtyping has been viewed as a way to narrow the range of a component in subtypes. In this paper, however, we see covariant deep subtyping in a new light -- a way to clarify a vague but fixed range of a component in subclasses. We will examine such concepts as class substitution, generic class by BETA/Cluster, and a number of theoretic approaches in relation to covariant deep subtyping.
The full paper is available by sending mail to the author shang@cadsun.corp.mot.com (David Lujun Shang).