摘要
Let Π be a cohomological irreducible cuspidal automorphic representation of GL 2 (A F ) with central character ω Π over a totally real number field F. In this paper, we prove the algebraicity of the near central non-critical value of the symmetric fourth L-function of Π twisted by ω Π −2 . The algebraicity is expressed in terms of the Petersson norm of the normalized newform of Π and the top degree Whittaker period of the Gelbart–Jacquet lift Sym 2 Π of Π.