English

Hypergeometric functions and algebraic curves $y^e=x^d+ax+b$

Number Theory 2019-03-25 v5

Abstract

Let qq be a prime power and Fq\mathbb{F}_q be a finite field with qq elements. Let ee and dd be positive integers. In this paper, for d2d\geq2 and q1(mod ed(d1))q\equiv1(\mathrm{mod}~ed(d-1)), we calculate the number of points on an algebraic curve Ee,d:ye=xd+ax+bE_{e,d}:y^e=x^d+ax+b over a finite field Fq\mathbb{F}_q in terms of dFd1_dF_{d-1} Gaussian hypergeometric series with multiplicative characters of orders dd and e(d1)e(d-1), and in terms of d1Fd2_{d-1}F_{d-2} Gaussian hypergeometric series with multiplicative characters of orders ed(d1)ed(d-1) and e(d1)e(d-1). This helps us to express the trace of Frobenius endomorphism of an algebraic curve Ee,dE_{e,d} over a finite field Fq\mathbb{F}_q in terms of the above hypergeometric series. As applications, we obtain some transformations and special values of 2F1_2F_{1} Gaussian hypergeometric series.

Keywords

Cite

@article{arxiv.1604.07613,
  title  = {Hypergeometric functions and algebraic curves $y^e=x^d+ax+b$},
  author = {Pramod Kumar Kewat and Ram Kumar},
  journal= {arXiv preprint arXiv:1604.07613},
  year   = {2019}
}
R2 v1 2026-06-22T13:41:04.665Z