Morse theory and Hilbert’s 19th problem
Let Ω⊂RnΩ⊂Rn\Omega \subset {\mathbb {R}}^n be a smooth C1C1C^1 compact domain, φ:Ω→RNφ:Ω→RN\varphi : \Omega \rightarrow {\mathbb {R}}^N in W1,k(Ω,RN)W1,k(Ω,RN)W^{1,k}(\Omega , {\mathbb {R}}^N) for all k. Furthermore let F:Ω×RnN→RF:Ω×RnN→RF: \Omega \times {\mathbb {R}}^{nN} \rightarrow {\mathbb {R}},...
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| Main Authors: | , |
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| Format: | Article (Journal) |
| Language: | English |
| Published: |
20 September 2019
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| In: |
Calculus of variations and partial differential equations
Year: 2019, Volume: 58, Issue: 5 |
| ISSN: | 1432-0835 |
| DOI: | 10.1007/s00526-019-1614-0 |
| Online Access: | Verlag, Volltext: https://doi.org/10.1007/s00526-019-1614-0
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| Author Notes: | F. Tomi, A. Tromba |
| Summary: | Let Ω⊂RnΩ⊂Rn\Omega \subset {\mathbb {R}}^n be a smooth C1C1C^1 compact domain, φ:Ω→RNφ:Ω→RN\varphi : \Omega \rightarrow {\mathbb {R}}^N in W1,k(Ω,RN)W1,k(Ω,RN)W^{1,k}(\Omega , {\mathbb {R}}^N) for all k. Furthermore let F:Ω×RnN→RF:Ω×RnN→RF: \Omega \times {\mathbb {R}}^{nN} \rightarrow {\mathbb {R}}, F(x, p), be C0,C0,C^0, differentiable with respect to p, and with DpFDpFD_p F continuous on Ω×RnNΩ×RnN\Omega \times {\mathbb {R}}^{nN} and strictly convex in p. Consider an nN×nNnN×nNnN \times nN matrix Aijαβ∈C0(Ω)Aαβij∈C0(Ω)A^{ij}_{\alpha \beta } \in C^0(\Omega ) satisfying Aijαβ(x)ξiαξjβ=Ajiβα(x)ξiαξjβ≥λ|ξ|2,λ>0Aαβij(x)ξαiξβj=Aβαji(x)ξαiξβj≥λ|ξ|2,λ>0\begin{aligned} A^{i j}_{\alpha \beta }(x) \xi ^i_\alpha \xi ^j_{\beta } = A^{ji}_{\beta \alpha }(x) \xi ^i_\alpha \xi ^j_\beta \ge \lambda |\xi |^2,\quad \lambda >0 \end{aligned} (0.1)Suppose that lim|p|→∞1|p|(DpF(x,p)−A(x)p)=0lim|p|→∞1|p|(DpF(x,p)−A(x)p)=0\begin{aligned} \lim _{|p| \rightarrow \infty } \tfrac{1}{|p|} \left( D_p F(x,p) - A(x) p \right) =0 \end{aligned} (0.2)uniformly in x. Consider the functional J(u):=∫ΩF(x,Du(x))dxJ(u):=∫ΩF(x,Du(x))dx\begin{aligned} J(u) := \int _\Omega F(x, D u(x)) \; dx \end{aligned} (0.3)for all u, u∣∣∣∣∂Ω=φu||∂Ω=φ{ \left. u \phantom {\big |} \right| _{\partial \Omega } }= \varphi , u∈φ+W1,20(Ω,RN)u∈φ+W01,2(Ω,RN)u\in \varphi + W^{1,2}_0 (\Omega , {\mathbb {R}}^N). Then J has a unique minimum which is Hölder continuous up to the boundary for all Hölder exponents αα\alpha , 0<α<10<α<10<\alpha < 1. We conclude with showing that our result is nearly optimal. Our approach is completely new, using for the first time, Morse theoretic ideas to prove, in one step, existence and regularity up to the boundary by minimizing the functional J within the Sobolev space W1,kW1,kW^{1,k} for arbitrarily large k. Using the method of energy growth estimates, Mariano Giaquinta in his ETH lectures, showed the Hölder continuity of W1,2W1,2W^{1,2} minimizers in the interior of ΩΩ\Omega under the single condition F(p)/|p|2→1F(p)/|p|2→1F(p)/|p|^2 \rightarrow 1 (as p→∞p→∞p\rightarrow \infty ) which, in our case, corresponds to Aijαβ=δijδαβAαβij=δijδαβ{A}^{ij}_{\alpha \beta } = \delta ^{ij}\delta _{\alpha \beta }. |
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| Item Description: | Gesehen am 11.11.2019 |
| Physical Description: | Online Resource |
| ISSN: | 1432-0835 |
| DOI: | 10.1007/s00526-019-1614-0 |