Extension of Splitting Fields over An Arbitrary Field












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Let $F$ be a field in which $0 neq2$ in $F$, and consider $f=x^4+1$. If $E$ is the splitting field for $f$ over $F$, it turns out that $E$ is a simple extension of $F$. How does one realize this fact? I'm not so sure as to what field element I can adjoin to $F$ to allow $f$ to split into linear factors. Finding the splitting field over something like $mathbb{Q}$ is straight forward and easy in comparison, but I'm having trouble working with any general field $F$.



Also, if we indeed did have that $0=2$ in our field $F$, then $f=x^4+1=(x+1)^4$, so $F$ is its own splitting field, is this correct reasoning?






abstract-algebra field-theory extension-field splitting-field







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  • 2




    $begingroup$
    Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
    $endgroup$
    – Mike Earnest
    58 mins ago


















4












$begingroup$


Let $F$ be a field in which $0 neq2$ in $F$, and consider $f=x^4+1$. If $E$ is the splitting field for $f$ over $F$, it turns out that $E$ is a simple extension of $F$. How does one realize this fact? I'm not so sure as to what field element I can adjoin to $F$ to allow $f$ to split into linear factors. Finding the splitting field over something like $mathbb{Q}$ is straight forward and easy in comparison, but I'm having trouble working with any general field $F$.



Also, if we indeed did have that $0=2$ in our field $F$, then $f=x^4+1=(x+1)^4$, so $F$ is its own splitting field, is this correct reasoning?






abstract-algebra field-theory extension-field splitting-field







share|cite|improve this question









$endgroup$








  • 2




    $begingroup$
    Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
    $endgroup$
    – Mike Earnest
    58 mins ago
















4












4








4


0



$begingroup$


Let $F$ be a field in which $0 neq2$ in $F$, and consider $f=x^4+1$. If $E$ is the splitting field for $f$ over $F$, it turns out that $E$ is a simple extension of $F$. How does one realize this fact? I'm not so sure as to what field element I can adjoin to $F$ to allow $f$ to split into linear factors. Finding the splitting field over something like $mathbb{Q}$ is straight forward and easy in comparison, but I'm having trouble working with any general field $F$.



Also, if we indeed did have that $0=2$ in our field $F$, then $f=x^4+1=(x+1)^4$, so $F$ is its own splitting field, is this correct reasoning?






abstract-algebra field-theory extension-field splitting-field







share|cite|improve this question









$endgroup$




Let $F$ be a field in which $0 neq2$ in $F$, and consider $f=x^4+1$. If $E$ is the splitting field for $f$ over $F$, it turns out that $E$ is a simple extension of $F$. How does one realize this fact? I'm not so sure as to what field element I can adjoin to $F$ to allow $f$ to split into linear factors. Finding the splitting field over something like $mathbb{Q}$ is straight forward and easy in comparison, but I'm having trouble working with any general field $F$.



Also, if we indeed did have that $0=2$ in our field $F$, then $f=x^4+1=(x+1)^4$, so $F$ is its own splitting field, is this correct reasoning?






abstract-algebra field-theory extension-field splitting-field




abstract-algebra field-theory extension-field splitting-field






share|cite|improve this question













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asked 1 hour ago









DevilofHell'sKitchenDevilofHell'sKitchen

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  • 2




    $begingroup$
    Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
    $endgroup$
    – Mike Earnest
    58 mins ago
















  • 2




    $begingroup$
    Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
    $endgroup$
    – Mike Earnest
    58 mins ago










2




2




$begingroup$
Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
$endgroup$
– Mike Earnest
58 mins ago






$begingroup$
Letting $alpha$ be any root, then $f$ splits as $(x-alpha)(x+alpha)(x-alpha^3)(x+alpha^3)$ in $F[alpha]$.
$endgroup$
– Mike Earnest
58 mins ago












1 Answer
1






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5












$begingroup$

If $theta$ is a root of $x^4+1$, then so are $theta^k$ for $k=1,3,5,7$, and so $x^4+1$ splits in $F(theta)$.






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$endgroup$









  • 2




    $begingroup$
    And those powers of $theta$ are distinct elements of the field.
    $endgroup$
    – Gerry Myerson
    50 mins ago











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1 Answer
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1 Answer
1






active

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active

oldest

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active

oldest

votes









5












$begingroup$

If $theta$ is a root of $x^4+1$, then so are $theta^k$ for $k=1,3,5,7$, and so $x^4+1$ splits in $F(theta)$.






share|cite|improve this answer









$endgroup$









  • 2




    $begingroup$
    And those powers of $theta$ are distinct elements of the field.
    $endgroup$
    – Gerry Myerson
    50 mins ago
















5












$begingroup$

If $theta$ is a root of $x^4+1$, then so are $theta^k$ for $k=1,3,5,7$, and so $x^4+1$ splits in $F(theta)$.






share|cite|improve this answer









$endgroup$









  • 2




    $begingroup$
    And those powers of $theta$ are distinct elements of the field.
    $endgroup$
    – Gerry Myerson
    50 mins ago














5












5








5





$begingroup$

If $theta$ is a root of $x^4+1$, then so are $theta^k$ for $k=1,3,5,7$, and so $x^4+1$ splits in $F(theta)$.






share|cite|improve this answer









$endgroup$



If $theta$ is a root of $x^4+1$, then so are $theta^k$ for $k=1,3,5,7$, and so $x^4+1$ splits in $F(theta)$.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered 1 hour ago









lhflhf

166k10171400




166k10171400








  • 2




    $begingroup$
    And those powers of $theta$ are distinct elements of the field.
    $endgroup$
    – Gerry Myerson
    50 mins ago














  • 2




    $begingroup$
    And those powers of $theta$ are distinct elements of the field.
    $endgroup$
    – Gerry Myerson
    50 mins ago








2




2




$begingroup$
And those powers of $theta$ are distinct elements of the field.
$endgroup$
– Gerry Myerson
50 mins ago




$begingroup$
And those powers of $theta$ are distinct elements of the field.
$endgroup$
– Gerry Myerson
50 mins ago


















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