Sunday, 3 August 2014

abstract algebra - Intuition about turning a polynomial ring into a field

Let's consider the polynomial ring R=F[x] over a field F. Then by taking the quotient by a principal ideal I=(f(x)) generated by an irreducible polynomial f(x), we obtain a field R=F[x]/(f(x)).




It's easy to see that R is indeed a field. Since the ideals of R which contain I are in bijective correspondence with the ideals of R, we can conclude that R has only two ideals and is therefore a field (as I is maximal in R since f(x) is irreducible).



I wanted to ask, is there an intuitive way of understanding why taking the quotient by some ideal makes F[x] into a field? I would ideally like some way of demonstrating that the existence of a nonzero polynomial equivalent to zero in R somehow allows us to describe an algorithm to calculate multiplicative inverses...

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