The External Fundamental Group of an Algebraic Number Field
نویسنده
چکیده
We associate to every algebraic number field K/Q a hyperbolic surface lamination and an external fundamental group IΓK : a generalization of the fundamental germ construction of [3], [4] that necessarily contains external (not first order definable) elements. The external fundamental group IΓQ is a split extension of the absolute Galois group ÎΓQ, that conjecturally contains a subgroup whose abelianization is isomorphic to the idèle class group.
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