ScalingStacks

Proposition 2.15 . [019E]

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Proposition 2.15.

[BFJ11, Proposition 8.1]

  • (i)

    PθP_{\theta} is non-decreasing: f≤g⇒Pθ​(f)≤Pθ​(g)f\leq g\Rightarrow P_{\theta}(f)\leq P_{\theta}(g).

  • (ii)

    Pθ​(f)P_{\theta}(f) is concave in both arguments:

    Pt​θ+(1−t)​θ′​(t​f+(1−t)​g)≥t​Pθ​(f)+(1−t)​Pθ′​(g)P_{t\theta+(1-t)\theta^{\prime}}\left(tf+(1-t)g\right)\geq tP_{\theta}(f)+(1-t)P_{\theta^{\prime}}(g)

    for 0≤t≤10\leq t\leq 1.

  • (iii)

    For each c∈𝐑c\in\mathbf{R} we have Pθ​(f+c)=Pθ​(f)+cP_{\theta}(f+c)=P_{\theta}(f)+c.

  • (iv)

    PθP_{\theta} is 11-Lipschitz continuous, i.e. supX|Pθ​(f)−Pθ​(g)|≤supX|f−g|\sup_{X}|P_{\theta}(f)-P_{\theta}(g)|\leq\sup_{X}|f-g|.

  • (v)

    Given a bounded function ff and a convergent sequence θm→θ\theta_{m}\to\theta in N1​(𝒳/S)N^{1}(\mathcal{X}/S) we have Pθm​(f)→Pθ​(f)P_{\theta_{m}}(f)\to P_{\theta}(f) uniformly on XX.

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