ScalingStacks

Verified tagged author-source HTML · 1904.03696v1 · cited publication edition alignment unverified.

00KA

Proposition 3.5. There exist algebra norms ⦀⋅⦀ϕaff\vvvert\mathord{\cdot}\vvvert_{\phi}^{\mathrm{aff}} on V∙​(L)V_{{\scriptscriptstyle\bullet}}(L) and ⦀⋅⦀ϕ,X|Yaff\vvvert\mathord{\cdot}\vvvert_{\phi,X|Y}^{\mathrm{aff}} on V∙​(LX|Y)V_{{\scriptscriptstyle\bullet}}(L_{X|Y}) such that the separated completions of (V∙(L),⦀⋅⦀ϕaff)(V_{{\scriptscriptstyle\bullet}}(L),\vvvert\mathord{\cdot}\vvvert_{\phi}^{\mathrm{aff}}) and (V∙(LX|Y),⦀⋅⦀ϕ,X|Yaff)(V_{{\scriptscriptstyle\bullet}}(L_{X|Y}),\vvvert\mathord{\cdot}\vvvert_{\phi,X|Y}^{\mathrm{aff}}) are affinoid algebras. Denote them by V^∙​(L,ϕaff)\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi^{\mathrm{aff}}) and V^∙​(LX|Y,ϕX|Yaff)\widehat{V}_{{\scriptscriptstyle\bullet}}(L_{X|Y},\phi_{X|Y}^{\mathrm{aff}}). Moreover, there exists a commutative diagram of homomorphisms of kk-algebras with σ\sigma and σY\sigma_{Y} being homomorphisms of Banach kk-algebras

V∙​(L)\textstyle{V_{{\scriptscriptstyle\bullet}}(L)\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces}iY\scriptstyle{i_{Y}}V^∙​(L,ϕaff)\textstyle{\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi^{\mathrm{aff}})\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces\ignorespaces}σ\scriptstyle{\sigma}iY​(ϕaff)\scriptstyle{i_{Y}(\phi^{\mathrm{aff}})}V^∙​(L,ϕ)\textstyle{\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi)\ignorespaces\ignorespaces\ignorespaces\ignorespaces}iY​(ϕ)\scriptstyle{i_{Y}(\phi)}V∙​(LX|Y)\textstyle{V_{{\scriptscriptstyle\bullet}}(L_{X|Y})\ignorespaces\ignorespaces\ignorespaces\ignorespaces}V^∙​(LX|Y,ϕX|Yaff)\textstyle{\widehat{V}_{{\scriptscriptstyle\bullet}}(L_{X|Y},\phi_{X|Y}^{\mathrm{aff}})\ignorespaces\ignorespaces\ignorespaces\ignorespaces}σ|Y\scriptstyle{\sigma|_{Y}}V^∙​(LX|Y,ϕX|Y)\textstyle{\widehat{V}_{{\scriptscriptstyle\bullet}}(L_{X|Y},\phi_{X|Y})}

All homomorphisms (except iYi_{Y}) have dense images, and iYi_{Y} is surjective.

00KB

Proof. As V∙​(L)V_{{\scriptscriptstyle\bullet}}(L) is a finitely generated sub-kk-algebra of V^∙​(L,ϕ)\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi) which is dense for the topology induced by Banach algebra norm, by Proposition 2.44, there exists an affinoid algebra norm ⦀⋅⦀ϕaff\vvvert\mathord{\cdot}\vvvert_{\phi}^{\mathrm{aff}} on V∙​(L)V_{{\scriptscriptstyle\bullet}}(L) and a homomorphism of Banach algebras

σ:V^∙​(L,ϕaff)→V^∙​(L,ϕ).\sigma:\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi^{\mathrm{aff}})\rightarrow\widehat{V}_{{\scriptscriptstyle\bullet}}(L,\phi).

One then takes ⦀⋅⦀ϕ,X|Yaff\vvvert\mathord{\cdot}\vvvert_{\phi,X|Y}^{\mathrm{aff}} on V∙​(LX|Y)V_{{\scriptscriptstyle\bullet}}(L_{X|Y}) to be the quotient norm of ⦀⋅⦀ϕaff\vvvert\mathord{\cdot}\vvvert_{\phi}^{\mathrm{aff}}. By Example 2.42, this quotient norm is also an affinoid algebra norm. By this quotient construction, there exists a homomorphism of Banach kk-algebras

σ|Y:V^∙​(LX|Y,ϕX|Yaff)→V^∙​(LX|Y,ϕX|Y)\sigma|_{Y}:\widehat{V}_{{\scriptscriptstyle\bullet}}(L_{X|Y},\phi_{X|Y}^{\mathrm{aff}})\rightarrow\widehat{V}_{{\scriptscriptstyle\bullet}}(L_{X|Y},\phi_{X|Y})

which fits into a commutative diagram with iY​(ϕ)i_{Y}(\phi) and iY​(ϕaff)i_{Y}(\phi^{\mathrm{aff}}). ∎

Original mathematics by the credited authors. Source collection and HTML conversion remain in progress.