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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Chapter 4<br />
INTRODUCTION<br />
LOCALISATION<br />
In this chapter, we <strong>in</strong>vestigate the localisation<br />
at prime ideals <strong>in</strong> GUFf{s. Persuaded by the importance<br />
of localisation <strong>in</strong> commutative r<strong>in</strong>gs and its application<br />
<strong>in</strong> t h c study of modules over c ommut a t i v e r<strong>in</strong>gs, several<br />
mathematicians <strong>in</strong>vestigated localisation at prime ideals<br />
<strong>in</strong> non-commutative r<strong>in</strong>gs, <strong>in</strong> particular <strong>in</strong> Noetherian<br />
r<strong>in</strong>gs, after Goldie proved his theorems for prime and<br />
semiprime Ncetherian r<strong>in</strong>gs.<br />
8 ut, bee()use 0 [ the 9 e nera 1 be la a v i 0 U r 0 f F) rime<br />
ideals <strong>in</strong> non-commutative r<strong>in</strong>gs, the complement of a<br />
prime ideal need not be a multiplicative set <strong>in</strong> general.<br />
Although the complement of every completely prime<br />
ideal<br />
<strong>in</strong> a Noetherian r<strong>in</strong>g is a multiplicative set, there are<br />
some completely prime ideals, whos e complements do<br />
not<br />
satisfy the ()re condition. Thus <strong>in</strong> general the<br />
localisation at the complement of a<br />
prime ideal can be<br />
ruled out <strong>in</strong> Noetherian r<strong>in</strong>gs.<br />
So,<br />
<strong>in</strong>stead of look<strong>in</strong>g at the complement of a<br />
prime ideal P <strong>in</strong> a<br />
Noetherian r<strong>in</strong>g R, jf we look at the<br />
set CR(P) = {r ~ R/r+P is regular <strong>in</strong> RIP} , then we<br />
can ga<strong>in</strong> someth<strong>in</strong>g. ~e say that a prime ideal <strong>in</strong> a