ScalingStacks

Proof. [04TC]

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Proof.

Lemma 5.3 and the inequality (4) imply that 𝒜t\mathcal{A}_{t} converge to a subset of 𝒜K\mathcal{A}_{K}. Indeed, for each tt we can rewrite |aj​tv⁡(j)​zj||a_{j}t^{v(j)}z^{j}| as |tcj​zj||t^{c_{j}}z^{j}|, cj=v⁡(j)+logt⁡|aj|c_{j}=v(j)+\log_{t}|a_{j}|. Such a monomial induces a linear function cj+j​xc_{j}+jx in ℝn+1\mathbb{R}^{n+1}. The inequalities

(5) ck+k​x≤maxj≠k⁡(cj+j​x)+logt⁡(N),c_{k}+kx\leq\max\limits_{j\neq k}(c_{j}+jx)+\log_{t}(N),

where N+1N+1 is the number of monomials in ftf_{t}, cut out a uniformly bounded neighborhood of 𝒜K\mathcal{A}_{K} which contains 𝒜K\mathcal{A}_{K}.

The limit of 𝒜t\mathcal{A}_{t} cannot be any smaller than 𝒜K\mathcal{A}_{K} by the following topological reason. A component of the complement of the set described by the inequalities (5) is given by the inequality ck+k​x>maxj≠k⁡(cj+j​x)+logt⁡(N)c_{k}+kx>\max\limits_{j\neq k}(c_{j}+jx)+\log_{t}(N). By [3] this component is contained in the component of ℝn+1∖𝒜t\mathbb{R}^{n+1}\smallsetminus\mathcal{A}_{t} corresponding to the index kk. Thus, different components of the set described by (5) must be contained in different components of ℝn+1∖𝒜t\mathbb{R}^{n+1}\smallsetminus\mathcal{A}_{t}. ∎

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