Let K be the real quadratic field, let HO/K be the narrow ring class field attached to an order O, let Vp be the relevant p-adic representation, and let resp denote the restriction map from global Mordell–Weil cohomology to local semistable cohomology. For an optimal embedding Ψ∈Emb(O,R), an ideal class a∈Pic(O), and a character \Greekmath011F:Gal(HO/K)→C×, use sΨ, sa⋆Ψ, and s\Greekmath011F for the associated Darmon cohomology classes. Rationality conjecture.
- For every optimal embedding Ψ∈Emb(O,R), there is a global class sΨ∈MW∗(HO,Vp) such that
sΨ=resp(sΨ).
- For every Ψ∈\mathpalette\overrightarrow@Emb+(O,R) and every a∈Pic(O), if \Greekmath011B=rec(a)−1∈Gal(HO/K), then
resp(\Greekmath011BsΨ)=sa⋆Ψ.
- For every character \Greekmath011F:Gal(HO/K)→C×, there is a class s\Greekmath011F∈MW\Greekmath011F(H\Greekmath011F,Vp) such that
s\Greekmath011F=resp(s\Greekmath011F),
where H\Greekmath011F/K is the abelian subextension cut out by \Greekmath011F and MW\Greekmath011F denotes its \Greekmath011F-isotypical subspace.
The conjecture predicts that locally defined Darmon classes arise by restriction from global cohomology classes and satisfy the expected reciprocity law. The text explicitly notes that part (3) follows from parts (1) and (2); no resolution is supplied.