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Every excellent ring is both universally catenary and Nagata. How "close" is a universally catenary Nagata ring to being excellent?

Context: I have not worked very much with the notions described above. While I certainly would not turn down a counterexample, I am more interested in getting an idea of how these notions are used in practice, and when it is appropriate to use one versus the other.

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In this article by Christel Rotthaus, she constructs a three-dimensional regular local ring which is Nagata (universally Japanese) but not excellent. Perhaps it will give you some idea of how hard one must work for such examples. gdz.sub.uni-goettingen.de/dms/load/img/?PPN=GDZPPN002418517 –  Graham Leuschke Dec 2 '11 at 20:27
    
Unfortunately, I don't speak a word of German, but thanks for the reference in any case. –  Charles Staats Dec 3 '11 at 2:10
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