Automorphic Forms, Cohomology and CAP Representations. The Case $GL_2$ over a definite quaternion algebra

Harald Grobner

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arXiv · 1003.2326

Automorphic Forms, Cohomology and CAP Representations. The Case $GL_2$ over a definite quaternion algebra

Harald Grobner

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Abstract

In this paper we fully describe the cuspidal and the Eisenstein cohomology of the group $G=GL_2$ over a definite quaternion algebra $D/\Q$. Functoriality is used to show the existence of residual and cuspidal automorphic forms, having cohomology in degree 1. The latter ones turn out to be CAP-representations, though $G$ satisfies Strong Multiplicity One. A non-vanishing result on intertwining operators of induced representations will serve as a starting point for further investigations concerning rationality of critical $L$-values.

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Harald Grobner. 2011-09-27. Automorphic Forms, Cohomology and CAP Representations. The Case $GL_2$ over a definite quaternion algebra. https://arxiv.org/abs/1003.2326

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