- #1
logarithmic
- 107
- 0
The first question is to find the ideals of R[x]/<x^2 - x>. I can see that the elements of the factor ring are of the form p(x) + <x^2 - x>, where p(x) is in R[x], which can be simplified to q(x)(x^2 - x) + r(x) + <x^2 - x> = r(x) + <x^2 - x>, where r(x) is of degree 1 or 0.
Now I'm pretty much stuck. Can we say anything more specific about r(x)? i.e. is it true that R[x]/<x^2 - x> = {ax + b + <x^2 - x> | a,b in R}? So now how do I find the ideals? It's easy to check if something's an ideal though.
My other question is to find the units in R = C[x,y]/<xy - 1>. So after writing out some definitions, this reduces to finding polynomials p(x,y) and q(x,y) not in <xy - 1>, such that p(x,y)q(x,y) = 1 (I think). So any element of C is a unit of R, what else is there? There may be some theorem that help simplify something. Any ideas?
Now I'm pretty much stuck. Can we say anything more specific about r(x)? i.e. is it true that R[x]/<x^2 - x> = {ax + b + <x^2 - x> | a,b in R}? So now how do I find the ideals? It's easy to check if something's an ideal though.
My other question is to find the units in R = C[x,y]/<xy - 1>. So after writing out some definitions, this reduces to finding polynomials p(x,y) and q(x,y) not in <xy - 1>, such that p(x,y)q(x,y) = 1 (I think). So any element of C is a unit of R, what else is there? There may be some theorem that help simplify something. Any ideas?