On lifting from classical groups to GLN
On lifting from classical groups to GLN
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从经典群体提升到 GLN
DOI:
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发表时间:
2001
期刊:
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通讯作者:
F. Shahidi
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文献类型:
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作者:
J. Cogdell;H. H. Kim;I. Piatetski;F. Shahidi
One of the most central questions in the theory of automorphic forms is that of Langlands’ functoriality or the lifting of automorphic representations [20, 2]. One of the most basic cases of functoriality would be the lifting of automorphic representations from the split classical groups to an appropriate GLN. It is this question we address in this paper. Take G to be a split classical group over a number field k. So G is one of the groups SO2n+1, SO2n, or Sp2n. The connected component LG0 of the Langlands dual group is Sp2n(C), SO2n(C), or SO2n+1(C) respectively. In each case there is a natural embedding of LG0 into GLN(C) = GLN for N = 2n, 2n, or 2n + 1 respectively. The philosophy of Langlands then says that associated to this map of dual groups there should exist a lifting of automorphic forms on G(Ak) to GLN(Ak). This map on dual groups also governs local liftings of irreducible admissible representations of G(kv) to GLN(kv) and these local and global liftings should be compatible. While there is at present no precise global conjecture on the nature of the lifting in our situation, the local lifting is well understood in several cases and the global lifting can be understood in terms of compatibility with the local lifts. If v is an archimedean place of k then every irreducible admissible representation πv of G(kv) is given by an admissible homomorphism of the local Weil group Wkv into LG0 [23, 2]. Composing with the map to GLN we get a parameter for an irreducible admissible representation Πv of GLN(kv). Πv is the local Langlands lift of πv. Similarly, if v is a non-archimedean place and πv an unramified admissible representation then πv is determined by its Satake parameter [tv] which is a semi-simple conjugacy class in LG0 [29, 2]. The image of [tv] under the L-homomorphism determines a conjugacy class in LGL 0 N and hence Satake parameters for an unramified representation Πv of GLN(kv). Again, Πv is the local Langlands lift of πv. If we have an irreducible automorphic representation π = ⊗′ πv of G(Ak) then for almost all places, namely the archimedean ones and the non-archimedean places where πv is unramified, the local component πv of π has a local lift Πv. We will say that a automorphic representation Π = ⊗Πv of GLN(Ak) is a weak Langlands lift of π, or simply a weak lift, if at the archimedean places and almost all non-archimedean places where πv is unramified Πv is in fact the local lift of πv.