[postgis-devel] Should EMPTY be spatially equal to self ?

[Paragon Corporation]

> Pretty much. Internally, the predicates do use DE9IM, except 
> for some optimizations implemented _before_ computing the 
> whole intersection matrix. Optimizations currently include 
> bounding box comparosons.
> 
> > FFF.FFF.FF2 is a sensible DE9IM matrix for empty - empty in set 
> > theoretical terms, but does it make sense to apply it for spatial 
> > predicates?  Many say yes, some say no.
> 
> I don't think anyone is suggesting NOT to use the matrix in 
> spatial predicates. I think what I'm suggesting to change the 
> definition of ST_Equals in matrix terms, or to introduce an 
> explicit corner case for the EMPTY case.
> 
> --strk;
> 
I had one of my Oracle firends test and his response. 
"This is what Oracle has:

 SELECT
ST_Geometry.ST_Point(0,0,NULL).ST_Equals(ST_Geometry.ST_Point(0,0,NULL)) as
testequals
   FROM dual;

TESTEQUALS
----------
1

That is, TRUE. as it should be."

At this point I don't really care strk.  I'm tired of arguing about it.  So
I will vote:

0-


I'm still not clear the benefit of changing and would rather not bother if
there is no benefit.

Thanks,
Regina