Counting points on smooth plane quartics
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Author(s) • •
Costa, Edgar
Harvey, David
Sutherland, Andrew V.
Date Issued
November 21, 2022
Publisher
Springer International Publishing
Citation
Research in Number Theory. 2022 Nov 21;9(1):1
Version
Final published version
Abstract
Abstract
We present efficient algorithms for counting points on a smooth plane quartic curve X modulo a prime p. We address both the case where X is defined over
$${\mathbb {F}}_p$$
F
p
and the case where X is defined over
$${\mathbb {Q}}$$
Q
and p is a prime of good reduction. We consider two approaches for computing
$$\#X({\mathbb {F}}_p)$$
#
X
(
F
p
)
, one which runs in
$$O(p\log p\log \log p)$$
O
(
p
log
p
log
log
p
)
time using
$$O(\log p)$$
O
(
log
p
)
space and one which runs in
$$O(p^{1/2}\log ^2p)$$
O
(
p
1
/
2
log
2
p
)
time using
$$O(p^{1/2}\log p)$$
O
(
p
1
/
2
log
p
)
space. Both approaches yield algorithms that are faster in practice than existing methods. We also present average polynomial-time algorithms for
$$X/{\mathbb {Q}}$$
X
/
Q
that compute
$$\#X({\mathbb {F}}_p)$$
#
X
(
F
p
)
for good primes
$$p\leqslant N$$
p
⩽
N
in
$$O(N\log ^3 N)$$
O
(
N
log
3
N
)
time using O(N) space. These are the first practical implementations of average polynomial-time algorithms for curves that are not cyclic covers of
$${\mathbb {P}}^1$$
P
1
, which in combination with previous results addresses all curves of genus
$$g\leqslant 3$$
g
⩽
3
. Our algorithms also compute Cartier–Manin/Hasse–Witt matrices that may be of independent interest.
MIT Department
Massachusetts Institute of Technology. Department of Mathematics
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Creative Commons Attribution
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DOI of Published Version
https://doi.org/10.1007/s40993-022-00397-8