polygon overlay - Mailing list pgsql-sql

Hi,

I don't see any overlap between the polygon and the box in the following 
sql. Can anyone explain why it returns 't'?
 select polygon(path '((0,0),(10,10),(20,10),(10,0))') && polygon(box 
'((16,0),(17,1))'); ?column?
---------- t
(1 row)

Thanks,
Gary