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Studies in Rings generalised Unique Factorisation Rings

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-23-<br />

Def<strong>in</strong>ition 1 048.<br />

A doma<strong>in</strong> which satisfies the condition of<br />

Corollary 1 047 is called a right Ore doma<strong>in</strong>. Left Ore<br />

doma<strong>in</strong>s are def<strong>in</strong>ed analogously.<br />

Ore's theor~m, though proved <strong>in</strong> 1930, was only a<br />

theoretical curiosity for a<br />

long time until Alfred Goldie<br />

proved some<br />

results, nowadays known as Goldie's theorems,<br />

<strong>in</strong> this direction <strong>in</strong> 1958. The importance of Goldie's<br />

theorems is that it paved the way<br />

to many new <strong>in</strong>vestigations<br />

and answered many questions posed on<br />

non-commutative r<strong>in</strong>g<br />

theory. We have seen that there are many non-commutative<br />

doma<strong>in</strong>s whic~ do not possess a right or left division r<strong>in</strong>g<br />

of fractions and there are many r<strong>in</strong>gs which do not have<br />

any factor r<strong>in</strong>gs<br />

which are right or left Ore doma<strong>in</strong>s.<br />

Instead of look<strong>in</strong>g for Ore doma<strong>in</strong>s and<br />

division r<strong>in</strong>gs of<br />

fractions, we look for r<strong>in</strong>gs from which Simple Art<strong>in</strong>ian<br />

r<strong>in</strong>gs can be built us<strong>in</strong>g fractions.<br />

Goldie's ma<strong>in</strong> result<br />

states that if R is a Noetherian r<strong>in</strong>g with 0 a prime ideal<br />

(p a prime ideal), then R has (Rip has) a simple Art<strong>in</strong>ian<br />

r<strong>in</strong>g of fractions. It turns out to be no extra work to<br />

<strong>in</strong>vestigate r<strong>in</strong>gs from which semisimple r<strong>in</strong>g of fractions<br />

can be builto We beg<strong>in</strong> with some def<strong>in</strong>itions.

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