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10 votes
2 answers
932 views

On the Galois group of the compositions of polynomials

We reprint an old math SE question here (see https://math.stackexchange.com/questions/1241224/composition-of-polynomials-and-galois-theory): " Let $f(x)$ be a polynomial of degree $n$ over $\...
Bernhard Boehmler's user avatar
7 votes
1 answer
382 views

Inverse Galois problem for non-Galois extensions

The inverse Galois problem asks whether every finite group appears as the Galois group of a Galois extension of the rational numbers. Is anything known about the anologous problem, where the ...
Jens Hemelaer's user avatar
17 votes
1 answer
448 views

The possible degrees of $\mathbb{Q}(a,b)$ in terms of the degrees of $a$ and $b$

Given two positive integers $n,m$, which positive integers $d$ appear as the degree of $\mathbb{Q}(a,b)$ for two algebraic numbers $a$ and $b$ of degrees $n$ resp. $m$? Two necessary conditions are $\...
HeinrichD's user avatar
  • 5,482
14 votes
0 answers
1k views

Is there an infinite field of characteristic 2 whose multiplicative group is torsion free and (direct-sum) indecomposable?

Let $F$ be a infinite field of characteristic 2 whose multiplicative group $F^*$ is torsion free. I would like to conclude that $F^*$ is decomposable or find an example where $F^*$ is indecomposable. ...
Chebolu's user avatar
  • 575
5 votes
2 answers
683 views

Reducing 12th degree eqns (12T179) to an 11th degree eqn

I always wondered if the fact that the quartic can be solved by a cubic can be generalized to other even degrees $n$, namely if there is an ordering of the roots $x_i$ of form $x_1x_2+x_3x_4+\dots+x_{...
Tito Piezas III's user avatar