ScalingStacks

Proof. [027K]

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

Proof.

(1) and (2) are consequences of (3) and (5) in Lemma 3.14, respectively.

(3) We set

f0(t1,…,tr):=μL¯⊗L¯1⊗t1⊗⋯⊗L¯r⊗tr(x)f_{0}(t_{1},\ldots,t_{r}):=\mu_{\overline{L}\otimes\overline{L}_{1}^{\otimes t_{1}}\otimes\cdots\otimes\overline{L}_{r}^{\otimes t_{r}}}(x)

for (t1,…,tr)∈(I1×⋯×Ir)∩ℚr(t_{1},\ldots,t_{r})\in(I_{1}\times\cdots\times I_{r})\cap{\mathbb{Q}}^{r}. By (1) and (2), for λ∈[0,1]∩ℚ\lambda\in[0,1]\cap{\mathbb{Q}} and (t1,…,tr),(t1′,…,tr′)∈(I1×⋯×Ir)∩ℚr(t_{1},\ldots,t_{r}),(t^{\prime}_{1},\ldots,t^{\prime}_{r})\in(I_{1}\times\cdots\times I_{r})\cap{\mathbb{Q}}^{r}, we have

f0​(λ⁡(t1,…,tr)+(1−λ)​(t1′,…,tr′))=μa(L¯⊗L¯1⊗t1⊗⋯⊗L¯r⊗tr)⊗λ⊗(L¯⊗L¯1⊗t1′⊗⋯⊗L¯r⊗tr′)⊗(1−λ)(x)≤λμL¯⊗L¯1⊗t1⊗⋯⊗L¯r⊗tr(x)+(1−λ)μL¯⊗L¯1⊗t1′⊗⋯⊗L¯r⊗tr′(x)=λ​f0​(t1,…,tr)+(1−λ)​f0​(t1′,…,tr′),f_{0}(\lambda(t_{1},\ldots,t_{r})+(1-\lambda)(t^{\prime}_{1},\ldots,t^{\prime}_{r}))\\ \hskip-50.00008pt=\mu^{\operatorname{a}}_{(\overline{L}\otimes\overline{L}_{1}^{\otimes t_{1}}\otimes\cdots\otimes\overline{L}_{r}^{\otimes t_{r}})^{\otimes\lambda}\otimes(\overline{L}\otimes\overline{L}_{1}^{\otimes t^{\prime}_{1}}\otimes\cdots\otimes\overline{L}_{r}^{\otimes t^{\prime}_{r}})^{\otimes(1-\lambda)}}(x)\\ \leq\lambda\mu_{\overline{L}\otimes\overline{L}_{1}^{\otimes t_{1}}\otimes\cdots\otimes\overline{L}_{r}^{\otimes t_{r}}}(x)+(1-\lambda)\mu_{\overline{L}\otimes\overline{L}_{1}^{\otimes t^{\prime}_{1}}\otimes\cdots\otimes\overline{L}_{r}^{\otimes t^{\prime}_{r}}}(x)\\ =\lambda f_{0}(t_{1},\ldots,t_{r})+(1-\lambda)f_{0}(t^{\prime}_{1},\ldots,t^{\prime}_{r}),

that is, f0f_{0} is concave on (I1×⋯×Ir)∩ℚr(I_{1}\times\cdots\times I_{r})\cap{\mathbb{Q}}^{r}. Therefore, the assertion (3) follows from [7, Corollary 1.3.2]. ∎

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