Defining polynomial
|
\(x^{8} + 8 x^{7} + 40 x^{6} + 112 x^{5} + 232 x^{4} + 240 x^{3} + 256 x^{2} + 96 x + 84\)
|
Invariants
| Base field: | $\Q_{2}$ |
| Degree $d$: | $8$ |
| Ramification exponent $e$: | $4$ |
| Residue field degree $f$: | $2$ |
| Discriminant exponent $c$: | $18$ |
| Discriminant root field: | $\Q_{2}$ |
| Root number: | $-1$ |
| $\card{ \Aut(K/\Q_{ 2 }) }$: | $4$ |
| This field is not Galois over $\Q_{2}.$ | |
| Visible slopes: | $[2, 7/2]$ |
Intermediate fields
| $\Q_{2}(\sqrt{5})$, $\Q_{2}(\sqrt{-1})$, $\Q_{2}(\sqrt{-5})$, 2.4.4.1, 2.4.9.2, 2.4.9.1 |
Fields in the database are given up to isomorphism. Isomorphic intermediate fields are shown with their multiplicities.
Unramified/totally ramified tower
| Unramified subfield: | $\Q_{2}(\sqrt{5})$ $\cong \Q_{2}(t)$ where $t$ is a root of
\( x^{2} + x + 1 \)
|
| Relative Eisenstein polynomial: |
\( x^{4} + 4 x^{3} + \left(4 t + 14\right) x^{2} + 8 x + 8 t + 10 \)
$\ \in\Q_{2}(t)[x]$
|
Ramification polygon
| Residual polynomials: | $z + 1$,$z^{2} + 1$ |
| Associated inertia: | $1$,$1$ |
| Indices of inseparability: | $[6, 2, 0]$ |
Invariants of the Galois closure
| Galois group: | $C_2\times D_4$ (as 8T9) |
| Inertia group: | Intransitive group isomorphic to $D_4$ |
| Wild inertia group: | $D_4$ |
| Unramified degree: | $2$ |
| Tame degree: | $1$ |
| Wild slopes: | $[2, 3, 7/2]$ |
| Galois mean slope: | $11/4$ |
| Galois splitting model: | $x^{8} - 2 x^{6} + 2 x^{4} - 4 x^{2} + 4$ |