The folklore conjecture on surjectivity and second cohomology over extensions of the cyclotomic field

From papers

Let pp be a prime with p3p\geqslant 3, let FcycF^{cyc} be the cyclotomic extension of FF, and let FSF^S be the maximal extension of FF unramified outside the specified set SS. For an extension LL of FcycF^{cyc} contained in FSF^S, let λL\lambda_L denote the map in the exact sequence referred to in the source, and let EpE_{p^{\infty}} denote the pp-primary torsion subgroup of the elliptic curve EE. Folklore conjecture. For every such extension LL, the map λL\lambda_L is surjective and

H2(FS/L,Ep)=0.H^2(F^S/L,E_{p^{\infty}})=0.

The vanishing is known for L=FL=F_{\infty}, but remains conjectural in general; the restriction p3p\geqslant 3 is necessary because the vanishing can fail for p=2p=2.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Susan Howson, “Homological characterisation of Lambda-ranks”, arXiv:math/9907215 (1999).

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