ScalingStacks

Proof. [01EI]

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Proof.

The map ev\ev is well-defined by Theorem 3.1 (i). It is a homeomorphism onto its image by Corollary 2.5 and the fact that any model is dominated by an SNC model. As XX is compact, we only need to show that ev⁡(X)\ev(X) is dense in lim←⁡Δ𝒳\varprojlim\Delta_{\mathcal{X}}. Pick s=(s𝒳)𝒳∈lim←⁡Δ𝒳s=(s_{\mathcal{X}})_{\mathcal{X}}\in\varprojlim\Delta_{\mathcal{X}} and fix an SNC model 𝒳\mathcal{X}. If 𝒴\mathcal{Y} is an SNC model dominated by 𝒳\mathcal{X}, then ev𝒳∘emb𝒳=id\ev_{\mathcal{X}}\circ\emb_{\mathcal{X}}=\id yields ev𝒴⁡(emb𝒳⁡(s𝒳))=s𝒴\ev_{\mathcal{Y}}(\emb_{\mathcal{X}}(s_{\mathcal{X}}))=s_{\mathcal{Y}}. Hence s=lim𝒳ev⁡(emb𝒳⁡(s𝒳))∈ev⁡(X)¯s=\lim_{\mathcal{X}}\ev(\emb_{\mathcal{X}}(s_{\mathcal{X}}))\in\overline{\ev(X)}. ∎

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