Minimal equation
Minimal equation
Simplified equation
$y^2 = 2x^5 + 4x^3 + x^2 + 2x + 1$ | (homogenize, simplify) |
$y^2 = 2x^5z + 4x^3z^3 + x^2z^4 + 2xz^5 + z^6$ | (dehomogenize, simplify) |
$y^2 = 2x^5 + 4x^3 + x^2 + 2x + 1$ | (homogenize, minimize) |
sage: R.<x> = PolynomialRing(QQ); C = HyperellipticCurve(R([1, 2, 1, 4, 0, 2]), R([]));
magma: R<x> := PolynomialRing(Rationals()); C := HyperellipticCurve(R![1, 2, 1, 4, 0, 2], R![]);
sage: X = HyperellipticCurve(R([1, 2, 1, 4, 0, 2]))
magma: X,pi:= SimplifiedModel(C);
Invariants
Conductor: | \( N \) | \(=\) | \(688\) | \(=\) | \( 2^{4} \cdot 43 \) | magma: Conductor(LSeries(C: ExcFactors:=[*<2,Valuation(688,2),R![1]>*])); Factorization($1);
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Discriminant: | \( \Delta \) | \(=\) | \(704512\) | \(=\) | \( 2^{14} \cdot 43 \) | magma: Discriminant(C); Factorization(Integers()!$1);
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Igusa-Clebsch invariants
Igusa invariants
G2 invariants
\( I_2 \) | \(=\) | \(128\) | \(=\) | \( 2^{7} \) |
\( I_4 \) | \(=\) | \(532\) | \(=\) | \( 2^{2} \cdot 7 \cdot 19 \) |
\( I_6 \) | \(=\) | \(26830\) | \(=\) | \( 2 \cdot 5 \cdot 2683 \) |
\( I_{10} \) | \(=\) | \(86\) | \(=\) | \( 2 \cdot 43 \) |
\( J_2 \) | \(=\) | \(512\) | \(=\) | \( 2^{9} \) |
\( J_4 \) | \(=\) | \(5248\) | \(=\) | \( 2^{7} \cdot 41 \) |
\( J_6 \) | \(=\) | \(-408576\) | \(=\) | \( - 2^{10} \cdot 3 \cdot 7 \cdot 19 \) |
\( J_8 \) | \(=\) | \(-59183104\) | \(=\) | \( - 2^{12} \cdot 14449 \) |
\( J_{10} \) | \(=\) | \(704512\) | \(=\) | \( 2^{14} \cdot 43 \) |
\( g_1 \) | \(=\) | \(2147483648/43\) | ||
\( g_2 \) | \(=\) | \(42991616/43\) | ||
\( g_3 \) | \(=\) | \(-6537216/43\) |
sage: C.igusa_clebsch_invariants(); [factor(a) for a in _]
magma: IgusaClebschInvariants(C); IgusaInvariants(C); G2Invariants(C);
Automorphism group
\(\mathrm{Aut}(X)\) | \(\simeq\) | $C_2$ | magma: AutomorphismGroup(C); IdentifyGroup($1);
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\(\mathrm{Aut}(X_{\overline{\Q}})\) | \(\simeq\) | $C_2$ | magma: AutomorphismGroup(ChangeRing(C,AlgebraicClosure(Rationals()))); IdentifyGroup($1);
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Rational points
All points: \((1 : 0 : 0),\, (0 : -1 : 1),\, (0 : 1 : 1)\)
magma: [C![0,-1,1],C![0,1,1],C![1,0,0]]; // minimal model
magma: [C![0,-1/2,1],C![0,1/2,1],C![1,0,0]]; // simplified model
Number of rational Weierstrass points: \(1\)
magma: #Roots(HyperellipticPolynomials(SimplifiedModel(C)));
This curve is locally solvable everywhere.
magma: f,h:=HyperellipticPolynomials(C); g:=4*f+h^2; HasPointsEverywhereLocally(g,2) and (#Roots(ChangeRing(g,RealField())) gt 0 or LeadingCoefficient(g) gt 0);
Mordell-Weil group of the Jacobian
Group structure: \(\Z/{10}\Z\)
magma: MordellWeilGroupGenus2(Jacobian(C));
Generator | $D_0$ | Height | Order | |||||
---|---|---|---|---|---|---|---|---|
\(D_0 - 2 \cdot(1 : 0 : 0)\) | \(x^2 + 2z^2\) | \(=\) | \(0,\) | \(y\) | \(=\) | \(xz^2 + z^3\) | \(0\) | \(10\) |
Generator | $D_0$ | Height | Order | |||||
---|---|---|---|---|---|---|---|---|
\(D_0 - 2 \cdot(1 : 0 : 0)\) | \(x^2 + 2z^2\) | \(=\) | \(0,\) | \(y\) | \(=\) | \(xz^2 + z^3\) | \(0\) | \(10\) |
Generator | $D_0$ | Height | Order | |||||
---|---|---|---|---|---|---|---|---|
\(D_0 - 2 \cdot(1 : 0 : 0)\) | \(x^2 + 2z^2\) | \(=\) | \(0,\) | \(y\) | \(=\) | \(1/2xz^2 + 1/2z^3\) | \(0\) | \(10\) |
BSD invariants
Hasse-Weil conjecture: | unverified |
Analytic rank: | \(0\) |
Mordell-Weil rank: | \(0\) |
2-Selmer rank: | \(1\) |
Regulator: | \( 1 \) |
Real period: | \( 6.426824 \) |
Tamagawa product: | \( 5 \) |
Torsion order: | \( 10 \) |
Leading coefficient: | \( 0.321341 \) |
Analytic order of Ш: | \( 1 \) (rounded) |
Order of Ш: | square |
Local invariants
Prime | ord(\(N\)) | ord(\(\Delta\)) | Tamagawa | L-factor | Cluster picture |
---|---|---|---|---|---|
\(2\) | \(4\) | \(14\) | \(5\) | \(1\) | |
\(43\) | \(1\) | \(1\) | \(1\) | \(( 1 - T )( 1 - 4 T + 43 T^{2} )\) |
Galois representations
The mod-$\ell$ Galois representation has maximal image \(\GSp(4,\F_\ell)\) for all primes \( \ell \) except those listed.
Prime \(\ell\) | mod-\(\ell\) image | Is torsion prime? |
---|---|---|
\(2\) | 2.60.1 | yes |
\(5\) | not computed | yes |
Sato-Tate group
\(\mathrm{ST}\) | \(\simeq\) | $\mathrm{USp}(4)$ |
\(\mathrm{ST}^0\) | \(\simeq\) | \(\mathrm{USp}(4)\) |
Decomposition of the Jacobian
Simple over \(\overline{\Q}\)
magma: HeuristicDecompositionFactors(C);
Endomorphisms of the Jacobian
Not of \(\GL_2\)-type over \(\Q\)
Endomorphism ring over \(\Q\):
\(\End (J_{})\) | \(\simeq\) | \(\Z\) |
\(\End (J_{}) \otimes \Q \) | \(\simeq\) | \(\Q\) |
\(\End (J_{}) \otimes \R\) | \(\simeq\) | \(\R\) |
All \(\overline{\Q}\)-endomorphisms of the Jacobian are defined over \(\Q\).
magma: //Please install CHIMP (https://github.com/edgarcosta/CHIMP) if you want to run this code
magma: HeuristicIsGL2(C); HeuristicEndomorphismDescription(C); HeuristicEndomorphismFieldOfDefinition(C);
magma: HeuristicIsGL2(C : Geometric := true); HeuristicEndomorphismDescription(C : Geometric := true); HeuristicEndomorphismLatticeDescription(C);