Abstract
We find summation identities and transformations for the McCarthy’s p-adic hypergeometric series by evaluating certain Gauss sums which appear while counting points on the family
over a finite field \(\mathbb {F}_p\). Salerno expresses the number of points over a finite field \(\mathbb {F}_p\) on the family \(Z_{\lambda }\) in terms of quotients of p-adic gamma functions under the condition that \(d|p-1\). In this paper, we first express the number of points over a finite field \(\mathbb {F}_p\) on the family \(Z_{\lambda }\) in terms of McCarthy’s p-adic hypergeometric series for any odd prime p not dividing \(d(d-1)\), and then deduce two summation identities for the p-adic hypergeometric series. We also find certain transformations and special values of the p-adic hypergeometric series. We finally find a summation identity for the Greene’s finite field hypergeometric series.
Résumé
Nous trouvons des identités et des transformations de sommations pour les séries p-adiques hypergéométriques de McCarthy en évaluant certaines sommes de Gauss qui apparaissent lorsque nous comptons le nombre de points sur un corps fini \(\mathbb {F}_p\) de la famille
Pour sa part, Salerno exprime le nombre de points sur un corps fini \( \mathbb {F}_p\) de la famille \(Z_{\lambda }\) en termes de quotients de fonctions gamma p-adiques sous la condition que d divise \(p-1\). Dans cet article, nous exprimons d’abord le nombre de points sur un corps fini \(\mathbb {F}_p\) de la famille \(Z_{\lambda }\) en termes de séries hypergéométriques p-adiques de McCarthy pour tout nombre premier impair p ne divisant pas \(d(d-1)\), et déduisons ensuite deux identités de sommations pour les séries hypergéométriques p-adiques. Nous trouvons aussi certaines transformations et des valeurs spéciales de séries hypergéométriques. Finalement, nous trouvons une identité de sommations pour les séries hypergéométriques sur un corps fini de Greene.
Similar content being viewed by others
References
Barman, R., Rahman, H., Saikia, N.: Counting points on Dwork hypersurfaces and \(p\)-adic hypergeometric function. Bull. Aust. Math. Soc. 94(2), 208–218 (2016)
Barman, R., Saikia, N., McCarthy, D.: Summation identities and special values of hypergeometric series in the \(p\)-adic setting. J. Number Theory 153, 63–84 (2015)
Barman, R., Saikia, N.: \(p\)-adic Gamma function and the polynomials \(x^d+ax+b\) and \(x^d+ax^{d-1}+b\) over \(\mathbb{F}_{q}\). Finite Fields Appl. 29, 89–105 (2014)
Barman, R., Saikia, N.: On the polynomials \(x^d+ax^i+b\) and \(x^d+ax^{d-i}+b\) over \(\mathbb{F}_q\) and Gaussian hypergeometric series. Ramanujan J. 35(3), 427–441 (2014)
Berndt, B., Evans, R., Williams, K.: Gauss and Jacobi Sums, Canadian Mathematical Society Series of Monographs and Advanced Texts, A Wiley-Interscience Publication. Wiley, New York (1998)
Candelas, P., de la Ossa, X., Rodríguez-Villegas, F.: Calabi–Yau manifolds over finite fields I. arXiv:hep-th/0012233
Candelas, P., de la Ossa, X., Rodríguez-Villegas, F.: Calabi–Yau manifolds over finite fields II. arXiv:hep-th/0402133
Dwork, B.: \(p\)-adic cycles. Pub. math. de l’I.H.É.S 37, 27–115 (1969)
Goodson, H.: Hypergeometric functions and relations to Dwork hypersurfaces. Int. J. Number Theory 13(2), 439–485 (2017)
Fuselier, J.: Hypergeometric functions over \(\mathbb{F}_p\) and relations to elliptic curve and modular forms. Proc. Am. Math. Soc. 138, 109–123 (2010)
Greene, J.: Hypergeometric functions over finite fields. Trans. Am. Math. Soc. 301(1), 77–101 (1987)
Gross, B.H., Koblitz, N.: Gauss sum and the \(p\)-adic \(\Gamma \)-function. Ann. Math. 109, 569–581 (1979)
Ireland, K., Rosen, M.: A Classical Introduction to Modern Number Theory, Springer International Edition. Springer, Berlin (2005)
Katz, N.M.: Exponential Sums and Differential Equations. Princeton University Press, Princeton (1990)
Koblitz, N.: \(p\)-adic analysis: a Short Course on Recent Work, London Mathematical Society. Lecture Note Series, vol. 46. Cambridge University Press, Cambridge (1980)
Lang, S.: Cyclotomic Fields I and II, Graduate Texts in Mathematics, vol. 121. Springer, New York (1990)
McCarthy, D.: Extending Gaussian hypergeometric series to the \(p\)-adic setting. Int. J. Number Theory 8(7), 1581–1612 (2012)
McCarthy, D.: The trace of Frobenius of elliptic curves and the \(p\)-adic gamma function. Pac. J. Math. 261(1), 219–236 (2013)
Salerno, A.: Counting points over finite fields and hypergeometric functions. Funct. Approx. Comment. Math. 49(1), 137–157 (2013)
Author information
Authors and Affiliations
Corresponding author
Additional information
We appreciate the careful review and thank the referee for helpful comments. This work is partially supported by a start up grant of the first author awarded by Indian Institute of Technology Guwahati. The second author acknowledges the financial support of Department of Science and Technology, Government of India for supporting a part of this work under INSPIRE Faculty Fellowship.
Rights and permissions
About this article
Cite this article
Barman, R., Saikia, N. Summation identities and transformations for hypergeometric series. Ann. Math. Québec 42, 133–157 (2018). https://doi.org/10.1007/s40316-017-0087-9
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s40316-017-0087-9
Keywords
- Character of finite fields
- Gauss sums
- Jacobi sums
- Gaussian hypergeometric series
- Teichmüller character
- p-adic Gamma function
- p-adic hypergeometric series
- Algebraic curves