my approach was based on the assumption that

送交者: Enlighten 于 2008-04-30, 12:43:37:

回答: what about this 由 steven 于 2008-04-30, 12:31:44:

every combination would find its equivalent area(s) on the VENN diagram.

now i'm not so sure...

maybe it's valid when we are allowed to use AND and NOT only. The OR will mess it up.