# Properties

 Label 2.4.ab_i Base Field $\F_{2^{2}}$ Dimension $2$ Ordinary No $p$-rank $1$ Principally polarizable Yes Contains a Jacobian No

## Invariants

 Base field: $\F_{2^{2}}$ Dimension: $2$ L-polynomial: $( 1 - x + 4 x^{2} )( 1 + 4 x^{2} )$ Frobenius angles: $\pm0.419569376745$, $\pm0.5$ Angle rank: $1$ (numerical) Jacobians: 0

This isogeny class is not simple.

## Newton polygon

 $p$-rank: $1$ Slopes: $[0, 1/2, 1/2, 1]$

## Point counts

This isogeny class is principally polarizable, but does not contain a Jacobian.

 $r$ 1 2 3 4 5 6 7 8 9 10 $A(\F_{q^r})$ 20 600 4940 54000 988100 17339400 272580860 4276044000 68515265780 1099903515000

 $r$ 1 2 3 4 5 6 7 8 9 10 $C(\F_{q^r})$ 4 32 76 208 964 4232 16636 65248 261364 1048952

## Decomposition and endomorphism algebra

Endomorphism algebra over $\F_{2^{2}}$
 The isogeny class factors as 1.4.ab $\times$ 1.4.a and its endomorphism algebra is a direct product of the endomorphism algebras for each isotypic factor. The endomorphism algebra for each factor is:
Endomorphism algebra over $\overline{\F}_{2^{2}}$
 The base change of $A$ to $\F_{2^{4}}$ is 1.16.h $\times$ 1.16.i. The endomorphism algebra for each factor is: 1.16.h : $$\Q(\sqrt{-15})$$. 1.16.i : the quaternion algebra over $$\Q$$ ramified at $2$ and $\infty$.
All geometric endomorphisms are defined over $\F_{2^{4}}$.

## Base change

This is a primitive isogeny class.

## Twists

Below are some of the twists of this isogeny class.
 Twist Extension Degree Common base change 2.4.b_i $2$ 2.16.p_dk 2.4.af_m $4$ 2.256.abx_boq 2.4.ad_e $4$ 2.256.abx_boq
Below is a list of all twists of this isogeny class.
 Twist Extension Degree Common base change 2.4.b_i $2$ 2.16.p_dk 2.4.af_m $4$ 2.256.abx_boq 2.4.ad_e $4$ 2.256.abx_boq 2.4.d_e $4$ 2.256.abx_boq 2.4.f_m $4$ 2.256.abx_boq 2.4.ad_k $12$ (not in LMFDB) 2.4.ab_g $12$ (not in LMFDB) 2.4.b_g $12$ (not in LMFDB) 2.4.d_k $12$ (not in LMFDB)