I'm not sure that I understand your question. Do you want the union of all the 
polygons? Or the polygon describing the area where they all intersect?

There is a function - unite? which you can use with a group by clause to get 
the union of a set of polys instead of just a pair. I'm not sure if the same 
function exists for intersection...

Chris

Quoting Ralph Mason <ralph.mason@telogis.com>:

> I know I am probably missing something very simple here.
> 
> But how would I find the smallest polygon bounding a set of overlapping
> polygons?
> 
> Thanks
> Ralph
> 
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