On the Saito-Kurokawa lifting
On the Saito-Kurokawa lifting
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关于斋藤黑川吊装
DOI:
10.1007/bf01389101
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发表时间:
1983
影响因子:
3.1
通讯作者:
I. Piatetski
中科院分区:
文献类型:
--
作者:
I. Piatetski;I. Piatetski
From calculations of numerical examples, H. Saito and N. Kurokawa conjectured that there exists a map from the space of classical holomorphic modular forms of weight 2k-2 into the space of holomorphic Siegel modular forms of weight k, for any even number k [11]. In a series of papers by Maass [12], Andrianov [13] and Zagier the Saito-Kurokawa conjecture was proved. A beautiful exposition of the proof and the history of the question can be found in the talk of Zagier Eli. N. Kurokawa computed his numerical examples in order to disprove the Ramanujan conjecture. At the same time, counter-examples of a different type were given by R. Howe & I. Piatetski-Shapiro [-2]. From the work of [3], we can deduce that if we have a Weil lifting from a group of small rank to a group of a bigger rank then the image does not satisfy the Ramanujan conjecture. Thus all cuspidal Weil liftings are counter examples.(For the precise definition of the Weil lifting see Sect. 1.) In the examples of R. Howe and I. Piatetski-Shapiro, the proof that the Weil lifting is a cuspidal automorphic representation is purely local. In other words some local component is supercuspidal. On the other hand, as we shall see, in the examples of Saito-Kurokawa type the reasons are essentially global. In this paper we present a new way of viewing the Saito-Kurokawa examples. Let us give a general description of our problem. Let G be any reductive group over a global field k, and let P= MS be a proper parabolic subgroup, where M is a Levi subgroup and S is the unipotent radical. Let z be an irreducible automorphic representation of M A. From a theorem of RP Lang-