Studies in Rings generalised Unique Factorisation Rings
Studies in Rings generalised Unique Factorisation Rings
Studies in Rings generalised Unique Factorisation Rings
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-1 lC)-<br />
Def<strong>in</strong>i.tion 4 038.<br />
Let R be a Noetherian r<strong>in</strong>g. A subset X of Spec R<br />
is said to be a .§J2arse<br />
subset if, given any Q € .Spec R<br />
and given any c £ CR(Q), we have<br />
Remark 4 039.<br />
Let R be a GUFR and I be a normal <strong>in</strong>vertible<br />
ideal of R. Put X I<br />
= '.p, Spec RI height P = 1 and I < pJ<br />
Then by pr<strong>in</strong>cipal ideal theorem XI /: (fjo LetQ ~ Spec 11<br />
and c £ C(Q). Then, if Q is m<strong>in</strong>imal,! cannot be<br />
conta<strong>in</strong>ed <strong>in</strong> Q, s<strong>in</strong>ce R is a GUFR, whereas<br />
n{p ~ XII Q < P and C f- C R<br />
(P)J conta<strong>in</strong>s I. Further,<br />
if Q is nonm<strong>in</strong>imal, then height of Q ~ 1 and so there<br />
exists no height 1 prime P such that Q < P and so<br />
'..{p E XI/Q < P, c ~ CR(P~== \21. Thus <strong>in</strong> both cases<br />
o f:: n{p f xr/o< P, c f- CR(P)J. Therefore X r is a<br />
s pa r s e set <strong>in</strong> R.<br />
The 0 r ern 4 0 40 •<br />
Let R be a GUFR and I be a normal <strong>in</strong>vertible ideal<br />
of R. Also assume that for a prime idealQ,{PE. XI/Q ~pJ<br />
is right s t ab Le , Then [p E. Xr/O ~pJ is a c La s s i c a l Ly<br />
right localis~ble<br />
seto