Converse theorem

In the mathematical theory of automorphic forms, a converse theorem gives sufficient conditions for a Dirichlet series to be the Mellin transform of a modular form. More generally a converse theorem states that a representation of an algebraic group over the adeles is automorphic whenever the L-functions of various twists of it are well behaved.

Weil's converse theorem

The first higher-dimensional converse theorem was proved by Hecke (1936) for level 1, who showed that if a Dirichlet series satisfied a certain functional equation and some growth conditions then it was the Mellin transform of a modular form of level 1. Weil (1967) found an extension to modular forms of higher level, which was described by Ogg (1969, chapter V). Weil's extension has the condition that not only the Dirichlet series, but also its twists by some Dirichlet characters, should satisfy functional equations.

Higher dimensions

J. W. Cogdell, H. Jacquet, I. I. Piatetski-Shapiro and J. Shalika have extended the converse theorem to automorphic forms on some higher dimensional groups, in particular GL_n and GL_m×GL_n, in a long series of papers.

References

• Cogdell, James W.; Piatetski-Shapiro, I. I. (2002), "Converse theorems, functoriality, and applications to number theory", in Li, Tatsien (ed.), Proceedings of the International Congress of Mathematicians, Vol. II (Beijing, 2002), Beijing: Higher Ed. Press, pp. 119–128, ISBN 978-7-04-008690-4, MR1957026arXiv:math/0304230
• Cogdell, James W. (2007), "L-functions and converse theorems for GL_n", in Sarnak, Peter; Shahidi, Freydoon (eds.), Automorphic forms and applications, IAS/Park City Math. Ser., vol. 12, Providence, R.I.: American Mathematical Society, pp. 97–177, ISBN 978-0-8218-2873-1, MR2331345
• Hecke, E. (1936), "Über die Bestimmung Dirichletscher Reihen durch ihre Funktionalgleichung", Mathematische Annalen, 112 (1): 664–699, doi:10.1007/BF01565437, ISSN 0025-5831
• Ogg, Andrew (1969), Modular forms and Dirichlet series, W. A. Benjamin, Inc., New York-Amsterdam, MR0256993
• Weil, André (1967), "Über die Bestimmung Dirichletscher Reihen durch Funktionalgleichungen", Mathematische Annalen, 168: 149–156, doi:10.1007/BF01361551, ISSN 0025-5831, MR0207658

External links

Cogdell's papers on converse theorems