Invariants
Base field: | $\F_{2^{4}}$ |
Dimension: | $2$ |
L-polynomial: | $( 1 - 5 x + 16 x^{2} )( 1 - 3 x + 16 x^{2} )$ |
$1 - 8 x + 47 x^{2} - 128 x^{3} + 256 x^{4}$ | |
Frobenius angles: | $\pm0.285098958592$, $\pm0.377642706461$ |
Angle rank: | $2$ (numerical) |
Jacobians: | $16$ |
Isomorphism classes: | 64 |
This isogeny class is not simple, primitive, ordinary, and not supersingular. It is principally polarizable and contains a Jacobian.
Newton polygon
This isogeny class is ordinary.
$p$-rank: | $2$ |
Slopes: | $[0, 0, 1, 1]$ |
Point counts
Point counts of the abelian variety
$r$ | $1$ | $2$ | $3$ | $4$ | $5$ |
---|---|---|---|---|---|
$A(\F_{q^r})$ | $168$ | $73920$ | $17749368$ | $4324320000$ | $1097994472008$ |
$r$ | $1$ | $2$ | $3$ | $4$ | $5$ | $6$ | $7$ | $8$ | $9$ | $10$ |
---|---|---|---|---|---|---|---|---|---|---|
$C(\F_{q^r})$ | $9$ | $287$ | $4329$ | $65983$ | $1047129$ | $16766687$ | $268416969$ | $4295014783$ | $68719748409$ | $1099511898527$ |
Jacobians and polarizations
This isogeny class contains the Jacobians of 16 curves (of which all are hyperelliptic), and hence is principally polarizable:
- $y^2+(x^2+x+a^3+a)y=ax^5+ax^3+x^2+ax+a^3+a$
- $y^2+(x^2+x+a^3+a^2+a)y=x^5+x^3+(a^2+1)x^2+(a^3+a^2+a)x+a+1$
- $y^2+(x^2+x+a^3+a^2)y=a^2x^5+a^2x^3+x^2+a^3x+a^3+a^2$
- $y^2+(x^2+x+a^3+1)y=x^5+(a^3+1)x^4+x^3+(a^3+a+1)x^2+(a^3+a^2+a+1)x+a^3+a^2+a$
- $y^2+(x^2+x+a^3+a)y=a^2x^5+a^2x^3+(a^2+1)x^2+(a+1)x+a^2$
- $y^2+(x^2+x+a^3)y=(a^2+1)x^5+a^3x^4+(a^2+1)x^3+(a^3+a^2+a)x^2+(a^3+a^2+a+1)x+a^3+a^2+a+1$
- $y^2+(x^2+x+a^3+a+1)y=(a+1)x^5+(a^3+a+1)x^4+(a+1)x^3+(a^3+a)x^2+(a^3+1)x+a^2+a+1$
- $y^2+(x^2+x+a^3+a^2)y=x^5+(a^3+a^2)x^4+x^3+a^3x^2+(a^3+a+1)x+a^3+a^2+1$
- $y^2+(x^2+x+a^3)y=(a+1)x^5+(a+1)x^3+ax^2+(a^2+1)x+a+1$
- $y^2+(x^2+x+a^3+a^2+1)y=ax^5+ax^3+(a^2+a+1)x^2+a^3x+a^2+1$
- $y^2+(x^2+x+a^3+1)y=(a^2+1)x^5+(a^3+1)x^4+(a^2+1)x^3+a^3x^2+(a^3+a^2+1)x+a^2+a$
- $y^2+(x^2+x+a^3+1)y=x^5+(a^3+1)x^4+x^3+(a^3+a)x^2+(a^3+a^2+a)x+a^2+a+1$
- $y^2+(x^2+x+a^3+a^2+1)y=(a+1)x^5+(a+1)x^3+(a^2+a+1)x^2+(a^2+a)x+a^2+1$
- $y^2+(x^2+x+a^3+a^2+a+1)y=ax^5+ax^3+(a+1)x^2+a^2x+a$
- $y^2+(x^2+x+a^3+1)y=(a^2+1)x^5+(a^2+1)x^3+a^2x^2+a^3x+a$
- $y^2+(x^2+x+a^3+a^2+a+1)y=a^2x^5+(a^3+a^2+a+1)x^4+a^2x^3+(a^3+1)x^2+a^3x+a^3$
Decomposition and endomorphism algebra
All geometric endomorphisms are defined over $\F_{2^{4}}$.
Endomorphism algebra over $\F_{2^{4}}$The isogeny class factors as 1.16.af $\times$ 1.16.ad and its endomorphism algebra is a direct product of the endomorphism algebras for each isotypic factor. The endomorphism algebra for each factor is: |
Base change
This is a primitive isogeny class.
Twists
Below is a list of all twists of this isogeny class.
Twist | Extension degree | Common base change |
---|---|---|
2.16.ac_r | $2$ | 2.256.be_zx |
2.16.c_r | $2$ | 2.256.be_zx |
2.16.i_bv | $2$ | 2.256.be_zx |