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Jun 24, 2011 at 23:23 vote accept ndk
Jun 24, 2011 at 23:23
Jun 22, 2011 at 19:56 history edited Kevin Buzzard CC BY-SA 3.0
typo :-/
Jun 22, 2011 at 19:55 comment added Kevin Buzzard classical Hodge Theory. On the other hand I still find it a little surprising that one "only" needs to adjoin all roots of unity and then complete -- I should look at the paper more closely. I guess Tate got away with adjoining all $p$-power roots of unity and completing in his $p$-divisible groups paper though, so perhaps I shouldn't be so surprised.
Jun 22, 2011 at 19:53 comment added Kevin Buzzard Olivier -- thanks for bringing this paper to my attention -- I was unaware of it. Although I've only taken a superficial glance at it, it seems to me that Ohta does not do what the OP wants: the OP specifically wants something over $\mathbf{Z}_p$ (this is my reading of the question). Ohta base changes to the integers of a p-adically complete field containing all roots of unity, and such an integer ring must be very far from $\mathbf{Z}_p$. Somehow it's less surprising that one can do something now, because one is closer to being able to use $p$-adic Hodge theory to replace Shimura's...
Jun 22, 2011 at 17:20 comment added Olivier Sure. M.Ohta On the p-adic Eichler-Shimura isomorphism for $\Lambda$-adic cusp forms (Crelle 463)+the fact that the Hecke algebra is complete intersection (under the assumptions that you know) thanks to Wiles/Taylor-Wiles to have a canonical splitting of the short exact sequence Ohta considers.
Jun 22, 2011 at 15:46 comment added Kevin Buzzard Olivier -- I know of no such Eichler-Shimura map, even in the ordinary case. Can you give a precise reference?
Jun 22, 2011 at 8:23 comment added Olivier Doesn't part of this works at least in the ordinary case though? Say the ordinary Hecke algebra is Gorenstein, then I think you do have such a canonical Eichler-Shimura map by the work of Mazur-Wiles and Ohta. All in all, this seems to me to indicate that indeed any natural such map will live in some $p$-adi period space, which happens to be your ring of coefficients in the ordinary case, so I guess I share the general pessimism.
Jun 22, 2011 at 6:08 vote accept ndk
Jun 22, 2011 at 6:08
Jun 22, 2011 at 5:36 history answered Kevin Buzzard CC BY-SA 3.0