Proposition 61.11.3. For every ring A there exists a faithfully flat, ind-étale ring map A \to D such that D is w-contractible.
Proof. Applying Lemma 61.8.7 to \text{id}_ A : A \to A we find a faithfully flat, ind-étale ring map A \to C such that C is w-local and such that every local ring at a maximal ideal of C is strictly henselian. Choose an extremally disconnected space T and a surjective continuous map T \to \pi _0(\mathop{\mathrm{Spec}}(C)), see Topology, Lemma 5.26.9. Note that T is profinite. Apply Lemma 61.6.2 to find an ind-Zariski ring map C \to D such that \pi _0(\mathop{\mathrm{Spec}}(D)) \to \pi _0(\mathop{\mathrm{Spec}}(C)) realizes T \to \pi _0(\mathop{\mathrm{Spec}}(C)) and such that
is cartesian in the category of topological spaces. Note that \mathop{\mathrm{Spec}}(D) is w-local, that \mathop{\mathrm{Spec}}(D) \to \mathop{\mathrm{Spec}}(C) is w-local, and that the set of closed points of \mathop{\mathrm{Spec}}(D) is the inverse image of the set of closed points of \mathop{\mathrm{Spec}}(C), see Lemma 61.2.5. Thus it is still true that the local rings of D at its maximal ideals are strictly henselian (as they are isomorphic to the local rings at the corresponding maximal ideals of C). It follows from Lemma 61.11.2 that D is w-contractible. \square
Comments (0)