Computing weight one modular forms over $\C$ and $\Fpbar$
Number Theory
2016-05-19 v2
Abstract
We report on a systematic computation of weight one cuspidal eigenforms for the group in characteristic zero and in characteristic . Perhaps the most surprising result was the existence of a mod 199 weight~1 cusp form of level 82 which does not lift to characteristic zero.
Keywords
Cite
@article{arxiv.1205.5077,
title = {Computing weight one modular forms over $\C$ and $\Fpbar$},
author = {Kevin Buzzard},
journal= {arXiv preprint arXiv:1205.5077},
year = {2016}
}
Comments
18 pages; second version incorporates a suggestion of Frank Calegari which makes a certain computation much more efficient (see Remark 8)