$p$-adic field 2.2.8.56a1.20

• Label: 2.2.8.56a1.20
• Base: \(\Q_{2}\)
• Degree: \(16\)
• e: \(8\)
• f: \(2\)
• c: \(56\)
• Galois group: $\OD_{16}:D_4$ (as 16T251)

Defining polynomial

$( x^{2} + x + 1 )^{8} + 8 x ( x^{2} + x + 1 )^{7} + 4 ( x^{2} + x + 1 )^{6} + 8 ( x^{2} + x + 1 )^{5} + 16 x ( x^{2} + x + 1 )^{4} + 16 ( x^{2} + x + 1 )^{3} + 16 ( x^{2} + x + 1 ) + 2$

Invariants

Base field:	$\Q_{2}$
Degree $d$:	$16$
Ramification index $e$:	$8$
Residue field degree $f$:	$2$
Discriminant exponent $c$:	$56$
Discriminant root field:	$\Q_{2}$
Root number:	$-1$
$\Aut(K/\Q_{2})$:	$C_4$
This field is not Galois over $\Q_{2}.$
Visible Artin slopes:	$[3, \frac{7}{2}, \frac{9}{2}]$
Visible Swan slopes:	$[2,\frac{5}{2},\frac{7}{2}]$
Means:	$\langle1, \frac{7}{4}, \frac{21}{8}\rangle$
Rams:	$(2, 3, 7)$
Jump set:	$[1, 3, 7, 15]$
Roots of unity:	$6 = (2^{ 2 } - 1) \cdot 2$

Intermediate fields

$\Q_{2}(\sqrt{5})$, $\Q_{2}(\sqrt{2\cdot 5})$, $\Q_{2}(\sqrt{2})$, 2.1.4.10a1.2, 2.1.4.10a1.1, 2.2.2.6a1.5, 2.2.4.20a1.1

Fields in the database are given up to isomorphism. Isomorphic intermediate fields are shown with their multiplicities.

Canonical tower

Unramified subfield:	$\Q_{2}(\sqrt{5})$ $\cong \Q_{2}(t)$ where $t$ is a root of \( x^{2} + x + 1 \)
Relative Eisenstein polynomial:	\( x^{8} + \left(8 t + 8\right) x^{7} + 4 x^{6} + 8 x^{5} + 16 x^{3} + 2 \) $\ \in\Q_{2}(t)[x]$

Ramification polygon

Residual polynomials:	$z^4 + 1$,$z^2 + 1$,$z + 1$
Associated inertia:	$1$,$1$,$1$
Indices of inseparability:	$[21, 14, 8, 0]$

Invariants of the Galois closure

Galois degree:	$128$
Galois group:	$\OD_{16}:D_4$ (as 16T251)
Inertia group:	Intransitive group isomorphic to $C_4^2:C_4$
Wild inertia group:	$C_4^2:C_4$
Galois unramified degree:	$2$
Galois tame degree:	$1$
Galois Artin slopes:	$[2, 3, 3, \frac{7}{2}, 4, \frac{9}{2}]$
Galois Swan slopes:	$[1,2,2,\frac{5}{2},3,\frac{7}{2}]$
Galois mean slope:	$4.0$
Galois splitting model:	$x^{16} + 6 x^{12} - 8 x^{10} + 85 x^{8} - 144 x^{6} + 82 x^{4} - 16 x^{2} + 1$