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Studies in Rings generalised Unique Factorisation Rings

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-108-<br />

M annihilated by I, I~(lV~) =<br />

is the <strong>in</strong>jective hull of M.<br />

00<br />

n<br />

U annE(M)I , where E(M)<br />

n=l<br />

Theorem 4035 ..<br />

Let P be a height 1 prime ideal of a GUFR. Then;'<br />

P satisfies the right second layer condition.<br />

P roof:<br />

Assume that there exists a prime ideal Q of R<br />

such that Q ( P and Q = ann M for some f<strong>in</strong>itely generated<br />

uniform right R-module M conta<strong>in</strong><strong>in</strong>g a copy U of a non<br />

zero right ideal of Rip. S<strong>in</strong>ce P is height 1 prime, Q<br />

is a m<strong>in</strong>imal prime<br />

ideal of R and so Q conta<strong>in</strong>s no<br />

normal <strong>in</strong>vertible Ldea k, Let I be the normal <strong>in</strong>vertible<br />

ideal conta<strong>in</strong>ed <strong>in</strong> P. Put J = I+Q. Then J/Q is an<br />

<strong>in</strong>vertible ideal of R/Q and so it has the right AR<br />

property.<br />

S<strong>in</strong>ce M is an R/Q module,by the above lemma<br />

00<br />

we have E(M) = U<br />

n=l<br />

annE(M) (J/Q)n. But M is f<strong>in</strong>itely<br />

generated and is conta<strong>in</strong>ed <strong>in</strong> E(M). This together with<br />

the fact that [annE(M) (J/Q)n) is an ascend<strong>in</strong>g cha<strong>in</strong> of<br />

submodules of E(M) implies that there exists a positive<br />

<strong>in</strong>teger k such<br />

that M S annE(M) (J/Q)k, ioe., M(J/Q)k=o<br />

which implies (J/Q)k ~ ann M = Q and Jk/Q (Q. Hence

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