ScalingStacks

Proposition 3.78 . [02MX]

Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.

Complete original source context · Original author HTML

Proposition 3.78.

Let A:Qℝ→NℝA\colon Q_{\mathbb{R}}\to N_{\mathbb{R}} be an affine map defined as A=H+u0A=H+u_{0} for a linear map HH and a point u0∈Nℝu_{0}\in N_{\mathbb{R}}. Let f∈𝒫Nℝf\in\mathscr{P}_{N_{\mathbb{R}}} (respectively f∈𝒫¯Nℝf\in{\overline{\mathscr{P}}}_{N_{\mathbb{R}}}) with dom⁡(f)∩im⁡(A)≠∅{\operatorname{dom}}(f)\cap\operatorname{im}(A)\not=\emptyset and g∈𝒫Qℝg\in\mathscr{P}_{Q_{\mathbb{R}}} (respectively g∈𝒫¯Qℝg\in{\overline{\mathscr{P}}}_{Q_{\mathbb{R}}}) such that stab⁡(g)∩im⁡(H∨)≠∅\operatorname{stab}(g)\cap\operatorname{im}(H^{\vee})\not=\emptyset. Then A∗​f∈𝒫QℝA^{\ast}f\in{\mathscr{P}}_{Q_{\mathbb{R}}} (respectively A∗​f∈𝒫¯QℝA^{*}f\in{\overline{\mathscr{P}}}_{Q_{\mathbb{R}}}) and A∗​g∈𝒫NℝA_{*}g\in\mathscr{P}_{N_{\mathbb{R}}} (respectively A∗​g∈𝒫¯NℝA_{*}g\in{\overline{\mathscr{P}}}_{N_{\mathbb{R}}}). Moreover,

  1. (1)

    stab⁡(A∗​f)=H∨​(stab⁡(f))\operatorname{stab}(A^{\ast}f)=H^{\vee}(\operatorname{stab}(f)), (A∗​f)∨=(H∨)∗​(f∨−u0)(A^{\ast}f)^{\vee}=(H^{\vee})_{\ast}(f^{\vee}-u_{0}) and, for all y∈stab⁡(A∗​f)y\in\operatorname{stab}(A^{\ast}f),

    (A∗​f)∨​(y)=maxx∈(H∨)−1​(y)⁡(f∨​(x)−⟨x,u0⟩);(A^{\ast}f)^{\vee}(y)=\max_{x\in(H^{\vee})^{-1}(y)}(f^{\vee}(x)-\langle x,u_{0}\rangle);
  2. (2)

    stab⁡(A∗​g)=(H∨)−1​(stab⁡(g))\operatorname{stab}(A_{\ast}g)=(H^{\vee})^{-1}(\operatorname{stab}(g)), (A∗​g)∨=(H∨)∗​(g∨)+u0(A_{\ast}g)^{\vee}=(H^{\vee})^{\ast}(g^{\vee})+u_{0} and, for all u∈dom⁡(A∗​g)u\in{\operatorname{dom}}(A_{*}g),

    A∗​g​(u)=maxv∈A−1​(u)⁡g⁡(v).A_{*}g(u)=\max_{v\in A^{-1}(u)}g(v).

Original mathematics by the credited authors. Source-backed reader collection; mathematical self-containment is not assessed.