[代數] 關於ring的問題
以下兩題請教各位網友
1.Which quotient ring is not isomorphic to GF32?
(A)GF2[x]/<x^5+x^2+1>
(B)GF2[x]/<x^5+x^4+x^2+x+1>
(C)GF2[x]/<x^5+x+1>
(D)GF2[x]/<x^5+x^3+x^2+x+1>
答案C
因為mod 2底下x^5+x+1可以分解成(x^2+x-1)(x^3-x^2-1)
其他選項都無法分解,但這是我用軟體算出來的
那在考試時應該如何判別呢
2.For a ring homomorphism f:GF2[x]<x^3+x^2+1> -> GF2[x]/<x^3+x+1> between
two quotient rings(GF8), which assignment of f(x) makes f an isomorphism?
(A)f(x)=x (B)f(x)=x^2 (C)f(x)=x+1 (D)f(x)=x^2+x
答案C
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