The Rees Valuations of Complete Ideals in a Regular Local Ring

Let I be a complete m-primary ideal of a regular local ring (R,m). In the case where R has dimension two, the beautiful theory developed by Zariski implies that I factors uniquely as a product of powers of simple complete ideals and each of the simple complete factors of I has a unique Rees valuation. In the higher dimensional case, a simple complete ideal of R often has more than one Rees valuation, and a complete m-primary ideal I may have finitely many or infinitely many base points. For the ideals having finitely many base points, Lipman proves a unique factorization involving special star-simple complete ideals with possibly negative exponents of the factors. Let T be an infinitely near point to R with dim R = dim T and T having residue field equal to R/m. We prove that the special star simple complete ideal associated with the sequence from R to T has a unique Rees valuation if and only if either dim R = 2 or there is no change of direction in the unique finite sequence of local quadratic transforms from R to T. We also examine conditions for a complete ideal to be projectively full.

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