A new notion of relativization
--- stringent relativization ---
has been proposed recently
for discussing collapsing relations of complexity classes, with which we hope to open a new approach for studying complexity classes.
Starting with the motivation of this notion, we discuss the meaning and implication of collapsing relations under the stringent relativization.
(This is a tech report version of the article presented in <EM>SIGACT News</EM>, Dec. 2006.?