Properties

Label 18.0.555...000.1
Degree $18$
Signature $[0, 9]$
Discriminant $-5.559\times 10^{27}$
Root discriminant \(34.78\)
Ramified primes $2,3,5$
Class number $12$ (GRH)
Class group [2, 6] (GRH)
Galois group $C_3^2 : C_2$ (as 18T4)

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Show commands: Magma / Oscar / PariGP / SageMath

Normalized defining polynomial

sage: x = polygen(QQ); K.<a> = NumberField(x^18 + 9*x^12 + 4887*x^6 + 27)
 
gp: K = bnfinit(y^18 + 9*y^12 + 4887*y^6 + 27, 1)
 
magma: R<x> := PolynomialRing(Rationals()); K<a> := NumberField(x^18 + 9*x^12 + 4887*x^6 + 27);
 
oscar: Qx, x = PolynomialRing(QQ); K, a = NumberField(x^18 + 9*x^12 + 4887*x^6 + 27)
 

\( x^{18} + 9x^{12} + 4887x^{6} + 27 \) Copy content Toggle raw display

sage: K.defining_polynomial()
 
gp: K.pol
 
magma: DefiningPolynomial(K);
 
oscar: defining_polynomial(K)
 

Invariants

Degree:  $18$
sage: K.degree()
 
gp: poldegree(K.pol)
 
magma: Degree(K);
 
oscar: degree(K)
 
Signature:  $[0, 9]$
sage: K.signature()
 
gp: K.sign
 
magma: Signature(K);
 
oscar: signature(K)
 
Discriminant:   \(-5559060566555523000000000000\) \(\medspace = -\,2^{12}\cdot 3^{33}\cdot 5^{12}\) Copy content Toggle raw display
sage: K.disc()
 
gp: K.disc
 
magma: OK := Integers(K); Discriminant(OK);
 
oscar: OK = ring_of_integers(K); discriminant(OK)
 
Root discriminant:  \(34.78\)
sage: (K.disc().abs())^(1./K.degree())
 
gp: abs(K.disc)^(1/poldegree(K.pol))
 
magma: Abs(Discriminant(OK))^(1/Degree(K));
 
oscar: (1.0 * dK)^(1/degree(K))
 
Galois root discriminant:  $2^{2/3}3^{11/6}5^{2/3}\approx 34.78475645409113$
Ramified primes:   \(2\), \(3\), \(5\) Copy content Toggle raw display
sage: K.disc().support()
 
gp: factor(abs(K.disc))[,1]~
 
magma: PrimeDivisors(Discriminant(OK));
 
oscar: prime_divisors(discriminant((OK)))
 
Discriminant root field:  \(\Q(\sqrt{-3}) \)
$\card{ \Gal(K/\Q) }$:  $18$
sage: K.automorphisms()
 
magma: Automorphisms(K);
 
oscar: automorphisms(K)
 
This field is Galois over $\Q$.
This is not a CM field.

Integral basis (with respect to field generator \(a\))

$1$, $a$, $a^{2}$, $a^{3}$, $a^{4}$, $a^{5}$, $\frac{1}{27}a^{6}+\frac{4}{9}$, $\frac{1}{27}a^{7}+\frac{4}{9}a$, $\frac{1}{27}a^{8}+\frac{4}{9}a^{2}$, $\frac{1}{54}a^{9}-\frac{1}{54}a^{6}-\frac{5}{18}a^{3}+\frac{5}{18}$, $\frac{1}{54}a^{10}-\frac{1}{54}a^{7}-\frac{5}{18}a^{4}+\frac{5}{18}a$, $\frac{1}{54}a^{11}-\frac{1}{54}a^{8}-\frac{5}{18}a^{5}+\frac{5}{18}a^{2}$, $\frac{1}{2916}a^{12}-\frac{5}{486}a^{6}-\frac{1}{2}a^{3}-\frac{137}{324}$, $\frac{1}{2916}a^{13}-\frac{5}{486}a^{7}-\frac{1}{2}a^{4}-\frac{137}{324}a$, $\frac{1}{2916}a^{14}-\frac{5}{486}a^{8}-\frac{1}{2}a^{5}-\frac{137}{324}a^{2}$, $\frac{1}{8748}a^{15}-\frac{5}{1458}a^{9}-\frac{1}{54}a^{6}+\frac{187}{972}a^{3}-\frac{2}{9}$, $\frac{1}{8748}a^{16}-\frac{5}{1458}a^{10}-\frac{1}{54}a^{7}+\frac{187}{972}a^{4}-\frac{2}{9}a$, $\frac{1}{8748}a^{17}-\frac{5}{1458}a^{11}-\frac{1}{54}a^{8}+\frac{187}{972}a^{5}-\frac{2}{9}a^{2}$ Copy content Toggle raw display

sage: K.integral_basis()
 
gp: K.zk
 
magma: IntegralBasis(K);
 
oscar: basis(OK)
 

Monogenic:  No
Index:  Not computed
Inessential primes:  $2$

Class group and class number

$C_{2}\times C_{6}$, which has order $12$ (assuming GRH)

sage: K.class_group().invariants()
 
gp: K.clgp
 
magma: ClassGroup(K);
 
oscar: class_group(K)
 

Unit group

sage: UK = K.unit_group()
 
magma: UK, fUK := UnitGroup(K);
 
oscar: UK, fUK = unit_group(OK)
 
Rank:  $8$
sage: UK.rank()
 
gp: K.fu
 
magma: UnitRank(K);
 
oscar: rank(UK)
 
Torsion generator:   \( \frac{7}{2916} a^{15} + \frac{5}{243} a^{9} + \frac{3775}{324} a^{3} + \frac{1}{2} \)  (order $6$) Copy content Toggle raw display
sage: UK.torsion_generator()
 
gp: K.tu[2]
 
magma: K!f(TU.1) where TU,f is TorsionUnitGroup(K);
 
oscar: torsion_units_generator(OK)
 
Fundamental units:   $\frac{1}{729}a^{15}+\frac{1}{1458}a^{12}+\frac{7}{486}a^{9}-\frac{1}{486}a^{6}+\frac{1049}{162}a^{3}+\frac{71}{81}$, $\frac{1}{8748}a^{15}-\frac{1}{2916}a^{12}-\frac{5}{1458}a^{9}-\frac{2}{243}a^{6}+\frac{673}{972}a^{3}+\frac{65}{324}$, $\frac{29}{8748}a^{17}-\frac{17}{8748}a^{15}-\frac{1}{972}a^{14}-\frac{1}{2916}a^{12}+\frac{22}{729}a^{11}-\frac{23}{1458}a^{9}-\frac{1}{162}a^{8}-\frac{2}{243}a^{6}+\frac{15683}{972}a^{5}-\frac{9389}{972}a^{3}-\frac{505}{108}a^{2}+\frac{65}{324}$, $\frac{29}{8748}a^{17}+\frac{13}{8748}a^{15}-\frac{1}{972}a^{14}+\frac{1}{2916}a^{12}+\frac{22}{729}a^{11}+\frac{8}{729}a^{9}-\frac{1}{162}a^{8}+\frac{13}{486}a^{6}+\frac{15683}{972}a^{5}+\frac{6967}{972}a^{3}-\frac{505}{108}a^{2}+\frac{169}{324}$, $\frac{26}{2187}a^{17}+\frac{17}{8748}a^{15}-\frac{5}{1458}a^{14}-\frac{1}{2916}a^{12}+\frac{155}{1458}a^{11}+\frac{23}{1458}a^{9}-\frac{13}{486}a^{8}-\frac{2}{243}a^{6}+\frac{28219}{486}a^{5}+\frac{9389}{972}a^{3}-\frac{1363}{81}a^{2}-\frac{907}{324}$, $\frac{179}{8748}a^{17}+\frac{5}{1458}a^{16}-\frac{11}{8748}a^{15}-\frac{5}{2916}a^{14}-\frac{1}{729}a^{13}-\frac{1}{972}a^{12}+\frac{133}{729}a^{11}+\frac{13}{486}a^{10}-\frac{13}{729}a^{9}-\frac{11}{486}a^{8}-\frac{7}{486}a^{7}-\frac{1}{162}a^{6}+\frac{97193}{972}a^{5}+\frac{1363}{81}a^{4}-\frac{5621}{972}a^{3}-\frac{2357}{324}a^{2}-\frac{725}{162}a-\frac{181}{108}$, $\frac{187}{4374}a^{17}-\frac{11}{1458}a^{15}+\frac{7}{1458}a^{14}-\frac{2}{729}a^{13}+\frac{1}{972}a^{12}+\frac{280}{729}a^{11}-\frac{17}{243}a^{9}+\frac{10}{243}a^{8}-\frac{7}{243}a^{7}+\frac{1}{162}a^{6}+\frac{101551}{486}a^{5}-\frac{2977}{81}a^{3}+\frac{3775}{162}a^{2}-\frac{1049}{81}a+\frac{451}{108}$, $\frac{25}{2916}a^{17}+\frac{4}{2187}a^{16}-\frac{49}{8748}a^{15}-\frac{7}{2916}a^{14}+\frac{1}{1458}a^{13}+\frac{1}{2916}a^{12}+\frac{37}{486}a^{11}+\frac{14}{729}a^{10}-\frac{79}{1458}a^{9}-\frac{5}{243}a^{8}+\frac{4}{243}a^{7}-\frac{7}{243}a^{6}+\frac{13585}{324}a^{5}+\frac{2179}{243}a^{4}-\frac{26821}{972}a^{3}-\frac{3613}{324}a^{2}+\frac{421}{162}a+\frac{439}{324}$ Copy content Toggle raw display (assuming GRH)
sage: UK.fundamental_units()
 
gp: K.fu
 
magma: [K|fUK(g): g in Generators(UK)];
 
oscar: [K(fUK(a)) for a in gens(UK)]
 
Regulator:  \( 3270633.26683 \) (assuming GRH)
sage: K.regulator()
 
gp: K.reg
 
magma: Regulator(K);
 
oscar: regulator(K)
 

Class number formula

\[ \begin{aligned}\lim_{s\to 1} (s-1)\zeta_K(s) =\mathstrut & \frac{2^{r_1}\cdot (2\pi)^{r_2}\cdot R\cdot h}{w\cdot\sqrt{|D|}}\cr \approx\mathstrut &\frac{2^{0}\cdot(2\pi)^{9}\cdot 3270633.26683 \cdot 12}{6\cdot\sqrt{5559060566555523000000000000}}\cr\approx \mathstrut & 1.33899809092 \end{aligned}\] (assuming GRH)

# self-contained SageMath code snippet to compute the analytic class number formula
 
x = polygen(QQ); K.<a> = NumberField(x^18 + 9*x^12 + 4887*x^6 + 27)
 
DK = K.disc(); r1,r2 = K.signature(); RK = K.regulator(); RR = RK.parent()
 
hK = K.class_number(); wK = K.unit_group().torsion_generator().order();
 
2^r1 * (2*RR(pi))^r2 * RK * hK / (wK * RR(sqrt(abs(DK))))
 
# self-contained Pari/GP code snippet to compute the analytic class number formula
 
K = bnfinit(x^18 + 9*x^12 + 4887*x^6 + 27, 1);
 
[polcoeff (lfunrootres (lfuncreate (K))[1][1][2], -1), 2^K.r1 * (2*Pi)^K.r2 * K.reg * K.no / (K.tu[1] * sqrt (abs (K.disc)))]
 
/* self-contained Magma code snippet to compute the analytic class number formula */
 
Qx<x> := PolynomialRing(QQ); K<a> := NumberField(x^18 + 9*x^12 + 4887*x^6 + 27);
 
OK := Integers(K); DK := Discriminant(OK);
 
UK, fUK := UnitGroup(OK); clK, fclK := ClassGroup(OK);
 
r1,r2 := Signature(K); RK := Regulator(K); RR := Parent(RK);
 
hK := #clK; wK := #TorsionSubgroup(UK);
 
2^r1 * (2*Pi(RR))^r2 * RK * hK / (wK * Sqrt(RR!Abs(DK)));
 
# self-contained Oscar code snippet to compute the analytic class number formula
 
Qx, x = PolynomialRing(QQ); K, a = NumberField(x^18 + 9*x^12 + 4887*x^6 + 27);
 
OK = ring_of_integers(K); DK = discriminant(OK);
 
UK, fUK = unit_group(OK); clK, fclK = class_group(OK);
 
r1,r2 = signature(K); RK = regulator(K); RR = parent(RK);
 
hK = order(clK); wK = torsion_units_order(K);
 
2^r1 * (2*pi)^r2 * RK * hK / (wK * sqrt(RR(abs(DK))))
 

Galois group

$C_3:S_3$ (as 18T4):

sage: K.galois_group(type='pari')
 
gp: polgalois(K.pol)
 
magma: G = GaloisGroup(K);
 
oscar: G, Gtx = galois_group(K); G, transitive_group_identification(G)
 
A solvable group of order 18
The 6 conjugacy class representatives for $C_3^2 : C_2$
Character table for $C_3^2 : C_2$

Intermediate fields

\(\Q(\sqrt{-3}) \), 3.1.300.1 x3, 3.1.972.1 x3, 3.1.6075.2 x3, 3.1.24300.3 x3, 6.0.270000.1, 6.0.2834352.1, 6.0.110716875.2, 6.0.1771470000.1, 9.1.43046721000000.2 x9

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

sage: K.subfields()[1:-1]
 
gp: L = nfsubfields(K); L[2..length(b)]
 
magma: L := Subfields(K); L[2..#L];
 
oscar: subfields(K)[2:end-1]
 

Sibling fields

Degree 9 sibling: 9.1.43046721000000.2
Minimal sibling: 9.1.43046721000000.2

Frobenius cycle types

$p$ $2$ $3$ $5$ $7$ $11$ $13$ $17$ $19$ $23$ $29$ $31$ $37$ $41$ $43$ $47$ $53$ $59$
Cycle type R R R ${\href{/padicField/7.3.0.1}{3} }^{6}$ ${\href{/padicField/11.2.0.1}{2} }^{9}$ ${\href{/padicField/13.3.0.1}{3} }^{6}$ ${\href{/padicField/17.2.0.1}{2} }^{9}$ ${\href{/padicField/19.3.0.1}{3} }^{6}$ ${\href{/padicField/23.2.0.1}{2} }^{9}$ ${\href{/padicField/29.2.0.1}{2} }^{9}$ ${\href{/padicField/31.3.0.1}{3} }^{6}$ ${\href{/padicField/37.3.0.1}{3} }^{6}$ ${\href{/padicField/41.2.0.1}{2} }^{9}$ ${\href{/padicField/43.3.0.1}{3} }^{6}$ ${\href{/padicField/47.2.0.1}{2} }^{9}$ ${\href{/padicField/53.2.0.1}{2} }^{9}$ ${\href{/padicField/59.2.0.1}{2} }^{9}$

In the table, R denotes a ramified prime. Cycle lengths which are repeated in a cycle type are indicated by exponents.

# to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Sage:
 
p = 7; [(e, pr.norm().valuation(p)) for pr,e in K.factor(p)]
 
\\ to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Pari:
 
p = 7; pfac = idealprimedec(K, p); vector(length(pfac), j, [pfac[j][3], pfac[j][4]])
 
// to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7 in Magma:
 
p := 7; [<pr[2], Valuation(Norm(pr[1]), p)> : pr in Factorization(p*Integers(K))];
 
# to obtain a list of $[e_i,f_i]$ for the factorization of the ideal $p\mathcal{O}_K$ for $p=7$ in Oscar:
 
p = 7; pfac = factor(ideal(ring_of_integers(K), p)); [(e, valuation(norm(pr),p)) for (pr,e) in pfac]
 

Local algebras for ramified primes

$p$LabelPolynomial $e$ $f$ $c$ Galois group Slope content
\(2\) Copy content Toggle raw display 2.6.4.1$x^{6} + 3 x^{5} + 10 x^{4} + 19 x^{3} + 22 x^{2} + 11 x + 7$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$
2.6.4.1$x^{6} + 3 x^{5} + 10 x^{4} + 19 x^{3} + 22 x^{2} + 11 x + 7$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$
2.6.4.1$x^{6} + 3 x^{5} + 10 x^{4} + 19 x^{3} + 22 x^{2} + 11 x + 7$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$
\(3\) Copy content Toggle raw display 3.6.11.8$x^{6} + 18 x^{2} + 21$$6$$1$$11$$S_3$$[5/2]_{2}$
3.6.11.8$x^{6} + 18 x^{2} + 21$$6$$1$$11$$S_3$$[5/2]_{2}$
3.6.11.8$x^{6} + 18 x^{2} + 21$$6$$1$$11$$S_3$$[5/2]_{2}$
\(5\) Copy content Toggle raw display 5.6.4.1$x^{6} + 12 x^{5} + 54 x^{4} + 122 x^{3} + 168 x^{2} + 228 x + 233$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$
5.6.4.1$x^{6} + 12 x^{5} + 54 x^{4} + 122 x^{3} + 168 x^{2} + 228 x + 233$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$
5.6.4.1$x^{6} + 12 x^{5} + 54 x^{4} + 122 x^{3} + 168 x^{2} + 228 x + 233$$3$$2$$4$$S_3$$[\ ]_{3}^{2}$