Friday, 3 January 2014

field theory - If L1/K and L2/K are not Galois (solvable), then L1L2/K is not Galois (solvable)

This is part of an exam preparation:




Prove/contradict:





  1. If L1/K and L2/K are not Galois, then L1L2/K is not Galois.

  2. If L1/K and L2/K are not solvable Galois extensions, then L1L2/K is not a solvable Galois extension.




For 1, I think that the answer is false. I thought of "splitting" the splitting field of a polynomial. For example, the splitting field of X32 over Q is Q(21/3,ω) and then taking Q(21/3) and Q(ω). The problem is that Q(w)/Q is Galois and I can't think of a different kinds of example.



For 2, I think that the answer is true. We have G1=Gal(L1L2/K)Gal(L1/K)×Gal(L2/K)=G2




Then I thought of making some claim about a subgup of a solvable group but Im not really sure how to proceed.



Thanks.

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