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lalitkumarj / OMSCategory

Sage Category implementation of OMS
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Dimension of cuspidal ordinary subspace and newforms #28

Closed rharron closed 11 years ago

rharron commented 11 years ago

Consider cusp forms of weight 2, tame level 4, and prime p = 7. Currently, we compute the rank of the cuspidal ordinary subspace by computing the number of non-zero roots mod p of the Hecke polynomial of p on level Np (in weight 2). BUT(!) In this case, there are no newforms of level 28. In fact, there is a newform of level 14. It is ordinary at 7. Under the two degeneracy maps from level 14 to 28, we get two dimensions of 7-ordinary cusp forms. But in some sense only one of these dimensions comes from a newform. What does this mean?

rpollack9974 commented 11 years ago

I'm not sure I understand. Why not just work at level 14 then?

rharron commented 11 years ago

Yeah, I guess so. This just confused me late last night. Probably should've just gone to bed.