MODULAR GALOIS REPRESENTATIONS OF "NEBEN" TYPE
MODULAR GALOIS REPRESENTATIONS OF "NEBEN" TYPE
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“NEBEN”类型的模伽罗瓦表示
DOI:
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发表时间:
2000
期刊:
影响因子:
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通讯作者:
H. Hida
中科院分区:
文献类型:
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作者:
H. Hida
In 1995 in [W] Theorem 0.2, A. Wiles proved, under some mild conditions (and relying on a ring theoretic result on Hecke algebras in [TW]), that if a p–adic Galois representation is congruent modulo p to that of an elliptic cusp form, then the representation itself is associated to a cusp form. After that, I have been thinking of characterizing residually dihedral Galois representations, because a 2-dim induced Galois representation is always modular. In this context, this paper is a continuation of the investigation done in [H98] and [HM97]. We have shown in [H98] (downloadable at www.math.ucla.edu/ hida) that for modular Galois representations of weight k 2 with real quadratic Neben type, the (odd) prime p giving residually dihedral representation is always a factor of N εk 1 1 for the positive fundamental unit ε of the quadratic extension, generalizing a result of Shimura in 1972 for weight 2. A simple application of this fact to the base-change problem was discussed in [HM97]. At the same time, I made a conjecture describing the universal p–ordinary deformation ring of a dihedral representation, which has been basically solved now by Cho-Vatsal [CV] (downloadable at www.math.ubc.ca/ vatsal). However the knowledge of the deformation ring does not give us an immediate method of constructing residually dihedral Galois representations. Here we would like to present a simple and (very elementary) constructive method, which actually gives all residually dihedral representations. As an obvious application of our result, we can show automatically the modularity of many non –rational elliptic –curves, –HBAV or rank two –motives, although we only discuss some examples of elliptic –curves in details in this paper (see Section 5). Some more background materials of this type of approach to the modularity problems of motives will be included in my forthcoming book [H00]. Also one of my students: Ami Fischman is now trying to use the idea here to make the result in [HM97] more systematic. Hereafter in this paper the prime p is assumed to be odd.