In this paper we completely solve the problem of when a Cantor dynamical system begin{document}$ (X, f) $end{document} can be embedded in begin{document}$ mathbb{R} $end{document} with vanishing derivative. For this purpose we construct a refining sequence of marked clopen partitions of begin{document}$ X $end{document} which is adapted to a dynamical system of this kind. It turns out that there is a huge class of such systems.
In this paper we completely solve the problem of when a Cantor dynamical system begin{document}$ (X, f) $end{document} can be embedded in begin{document}$ mathbb{R} $end{document} with vanishing derivative. For this purpose we construct a refining sequence of marked clopen partitions of begin{document}$ X $end{document} which is adapted to a dynamical system of this kind. It turns out that there is a huge class of such systems.
{"title":"A Cantor dynamical system is slow if and only if all its finite orbits are attracting","authors":"Silvère Gangloff, P. Oprocha","doi":"10.3934/dcds.2022007","DOIUrl":"https://doi.org/10.3934/dcds.2022007","url":null,"abstract":"<p style='text-indent:20px;'>In this paper we completely solve the problem of when a Cantor dynamical system <inline-formula><tex-math id=\"M1\">begin{document}$ (X, f) $end{document}</tex-math></inline-formula> can be embedded in <inline-formula><tex-math id=\"M2\">begin{document}$ mathbb{R} $end{document}</tex-math></inline-formula> with vanishing derivative. For this purpose we construct a refining sequence of marked clopen partitions of <inline-formula><tex-math id=\"M3\">begin{document}$ X $end{document}</tex-math></inline-formula> which is adapted to a dynamical system of this kind. It turns out that there is a huge class of such systems.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"100 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79338192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
By constructing explicit supersolutions, we obtain the optimal global Hölder regularity for several singular Monge-Ampère equations on general bounded open convex domains including those related to complete affine hyperbolic spheres, and proper affine hyperspheres. Our analysis reveals that certain singular-looking equations, such as begin{document}$ det D^2 u = |u|^{-n-2-k} (xcdot Du -u)^{-k} $end{document} with zero boundary data, have unexpected degenerate nature.
By constructing explicit supersolutions, we obtain the optimal global Hölder regularity for several singular Monge-Ampère equations on general bounded open convex domains including those related to complete affine hyperbolic spheres, and proper affine hyperspheres. Our analysis reveals that certain singular-looking equations, such as begin{document}$ det D^2 u = |u|^{-n-2-k} (xcdot Du -u)^{-k} $end{document} with zero boundary data, have unexpected degenerate nature.
{"title":"Optimal boundary regularity for some singular Monge-Ampère equations on bounded convex domains","authors":"N. Le","doi":"10.3934/dcds.2021188","DOIUrl":"https://doi.org/10.3934/dcds.2021188","url":null,"abstract":"<p style='text-indent:20px;'>By constructing explicit supersolutions, we obtain the optimal global Hölder regularity for several singular Monge-Ampère equations on general bounded open convex domains including those related to complete affine hyperbolic spheres, and proper affine hyperspheres. Our analysis reveals that certain singular-looking equations, such as <inline-formula><tex-math id=\"M1\">begin{document}$ det D^2 u = |u|^{-n-2-k} (xcdot Du -u)^{-k} $end{document}</tex-math></inline-formula> with zero boundary data, have unexpected degenerate nature.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75288738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The classical theorem of Jewett and Krieger gives a strictly ergodic model for any ergodic measure preserving system. An extension of this result for non-ergodic systems was given many years ago by George Hansel. He constructed, for any measure preserving system, a strictly uniform model, i.e. a compact space which admits an upper semicontinuous decomposition into strictly ergodic models of the ergodic components of the measure. In this note we give a new proof of a stronger result by adding the condition of purity, which controls the set of ergodic measures that appear in the strictly uniform model.
{"title":"Pure strictly uniform models of non-ergodic measure automorphisms","authors":"T. Downarowicz, B. Weiss","doi":"10.3934/dcds.2021140","DOIUrl":"https://doi.org/10.3934/dcds.2021140","url":null,"abstract":"The classical theorem of Jewett and Krieger gives a strictly ergodic model for any ergodic measure preserving system. An extension of this result for non-ergodic systems was given many years ago by George Hansel. He constructed, for any measure preserving system, a strictly uniform model, i.e. a compact space which admits an upper semicontinuous decomposition into strictly ergodic models of the ergodic components of the measure. In this note we give a new proof of a stronger result by adding the condition of purity, which controls the set of ergodic measures that appear in the strictly uniform model.","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81721218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce a new model of the logarithmic type of wave like plate equation with a nonlocal logarithmic damping mechanism. We consider the Cauchy problem for this new model in begin{document}$ {{bf R}}^{n} $end{document}, and study the asymptotic profile and optimal decay rates of solutions as begin{document}$ t to infty $end{document} in begin{document}$ L^{2} $end{document}-sense. The operator begin{document}$ L $end{document} considered in this paper was first introduced to dissipate the solutions of the wave equation in the paper studied by Charão-Ikehata [7]. We will discuss the asymptotic property of the solution as time goes to infinity to our Cauchy problem, and in particular, we classify the property of the solutions into three parts from the viewpoint of regularity of the initial data, that is, diffusion-like, wave-like, and both of them.
We introduce a new model of the logarithmic type of wave like plate equation with a nonlocal logarithmic damping mechanism. We consider the Cauchy problem for this new model in begin{document}$ {{bf R}}^{n} $end{document}, and study the asymptotic profile and optimal decay rates of solutions as begin{document}$ t to infty $end{document} in begin{document}$ L^{2} $end{document}-sense. The operator begin{document}$ L $end{document} considered in this paper was first introduced to dissipate the solutions of the wave equation in the paper studied by Charão-Ikehata [7]. We will discuss the asymptotic property of the solution as time goes to infinity to our Cauchy problem, and in particular, we classify the property of the solutions into three parts from the viewpoint of regularity of the initial data, that is, diffusion-like, wave-like, and both of them.
{"title":"A dissipative logarithmic-Laplacian type of plate equation: Asymptotic profile and decay rates","authors":"R. Charão, Alessandra Piske, R. Ikehata","doi":"10.3934/dcds.2021189","DOIUrl":"https://doi.org/10.3934/dcds.2021189","url":null,"abstract":"<p style='text-indent:20px;'>We introduce a new model of the logarithmic type of wave like plate equation with a nonlocal logarithmic damping mechanism. We consider the Cauchy problem for this new model in <inline-formula><tex-math id=\"M1\">begin{document}$ {{bf R}}^{n} $end{document}</tex-math></inline-formula>, and study the asymptotic profile and optimal decay rates of solutions as <inline-formula><tex-math id=\"M2\">begin{document}$ t to infty $end{document}</tex-math></inline-formula> in <inline-formula><tex-math id=\"M3\">begin{document}$ L^{2} $end{document}</tex-math></inline-formula>-sense. The operator <inline-formula><tex-math id=\"M4\">begin{document}$ L $end{document}</tex-math></inline-formula> considered in this paper was first introduced to dissipate the solutions of the wave equation in the paper studied by Charão-Ikehata [<xref ref-type=\"bibr\" rid=\"b7\">7</xref>]. We will discuss the asymptotic property of the solution as time goes to infinity to our Cauchy problem, and in particular, we classify the property of the solutions into three parts from the viewpoint of regularity of the initial data, that is, diffusion-like, wave-like, and both of them.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"254 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79474635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
with Dirichlet boundary conditions. Here begin{document}$ w $end{document} is a suitable weight and begin{document}$ g = G' $end{document} and begin{document}$ h = H' $end{document} are appropriated Young functions satisfying the so called begin{document}$ Delta' $end{document} condition, which includes for instance logarithmic perturbation of powers and different power behaviors near zero and infinity. We prove several properties on its spectrum, being our main goal to obtain lower bounds of eigenvalues in terms of begin{document}$ G $end{document}, begin{document}$ H $end{document}, begin{document}$ w $end{document} and the normalization begin{document}$ mu $end{document} of the corresponding eigenfunctions.
We introduce some new strategies to obtain results that generalize several inequalities from the literature of begin{document}$ p- $end{document}Laplacian type eigenvalues.
In this article we consider the following weighted nonlinear eigenvalue problem for the begin{document}$ g- $end{document}Laplacian begin{document}$ -{text{ div}}left( g(|nabla u|)frac{nabla u}{|nabla u|}right) = lambda w(x) h(|u|)frac{u}{|u|} quad text{ in }Omegasubset mathbb R^n, ngeq 1 $end{document} with Dirichlet boundary conditions. Here begin{document}$ w $end{document} is a suitable weight and begin{document}$ g = G' $end{document} and begin{document}$ h = H' $end{document} are appropriated Young functions satisfying the so called begin{document}$ Delta' $end{document} condition, which includes for instance logarithmic perturbation of powers and different power behaviors near zero and infinity. We prove several properties on its spectrum, being our main goal to obtain lower bounds of eigenvalues in terms of begin{document}$ G $end{document}, begin{document}$ H $end{document}, begin{document}$ w $end{document} and the normalization begin{document}$ mu $end{document} of the corresponding eigenfunctions.We introduce some new strategies to obtain results that generalize several inequalities from the literature of begin{document}$ p- $end{document}Laplacian type eigenvalues.
{"title":"Lower bounds for Orlicz eigenvalues","authors":"A. Salort","doi":"10.3934/dcds.2021158","DOIUrl":"https://doi.org/10.3934/dcds.2021158","url":null,"abstract":"<p style='text-indent:20px;'>In this article we consider the following weighted nonlinear eigenvalue problem for the <inline-formula><tex-math id=\"M1\">begin{document}$ g- $end{document}</tex-math></inline-formula>Laplacian</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id=\"FE1\"> begin{document}$ -{text{ div}}left( g(|nabla u|)frac{nabla u}{|nabla u|}right) = lambda w(x) h(|u|)frac{u}{|u|} quad text{ in }Omegasubset mathbb R^n, ngeq 1 $end{document} </tex-math></disp-formula></p><p style='text-indent:20px;'>with Dirichlet boundary conditions. Here <inline-formula><tex-math id=\"M2\">begin{document}$ w $end{document}</tex-math></inline-formula> is a suitable weight and <inline-formula><tex-math id=\"M3\">begin{document}$ g = G' $end{document}</tex-math></inline-formula> and <inline-formula><tex-math id=\"M4\">begin{document}$ h = H' $end{document}</tex-math></inline-formula> are appropriated Young functions satisfying the so called <inline-formula><tex-math id=\"M5\">begin{document}$ Delta' $end{document}</tex-math></inline-formula> condition, which includes for instance logarithmic perturbation of powers and different power behaviors near zero and infinity. We prove several properties on its spectrum, being our main goal to obtain lower bounds of eigenvalues in terms of <inline-formula><tex-math id=\"M6\">begin{document}$ G $end{document}</tex-math></inline-formula>, <inline-formula><tex-math id=\"M7\">begin{document}$ H $end{document}</tex-math></inline-formula>, <inline-formula><tex-math id=\"M8\">begin{document}$ w $end{document}</tex-math></inline-formula> and the normalization <inline-formula><tex-math id=\"M9\">begin{document}$ mu $end{document}</tex-math></inline-formula> of the corresponding eigenfunctions.</p><p style='text-indent:20px;'>We introduce some new strategies to obtain results that generalize several inequalities from the literature of <inline-formula><tex-math id=\"M10\">begin{document}$ p- $end{document}</tex-math></inline-formula>Laplacian type eigenvalues.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87791754","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We determine the asymptotic spreading speed of the solutions of a Fisher-KPP reaction-diffusion equation, starting from compactly supported initial data, when the diffusion coefficient is a fixed bounded monotone profile that is shifted at a given forcing speed and satisfies a general uniform ellipticity condition. Depending on the monotonicity of the profile, we are able to characterize this spreading speed as a function of the forcing speed and the two linear spreading speeds associated to the asymptotic problems at begin{document}$ x = pm infty $end{document}. Most notably, when the profile of the diffusion coefficient is increasing we show that there is an intermediate range for the forcing speed where spreading actually occurs at a speed which is larger than the linear speed associated with the homogeneous state around the position of the front. We complement our study with the construction of strictly monotone traveling front solutions with strong exponential decay near the unstable state when the profile of the diffusion coefficient is decreasing and in the regime where the forcing speed is precisely the selected spreading speed.
We determine the asymptotic spreading speed of the solutions of a Fisher-KPP reaction-diffusion equation, starting from compactly supported initial data, when the diffusion coefficient is a fixed bounded monotone profile that is shifted at a given forcing speed and satisfies a general uniform ellipticity condition. Depending on the monotonicity of the profile, we are able to characterize this spreading speed as a function of the forcing speed and the two linear spreading speeds associated to the asymptotic problems at begin{document}$ x = pm infty $end{document}. Most notably, when the profile of the diffusion coefficient is increasing we show that there is an intermediate range for the forcing speed where spreading actually occurs at a speed which is larger than the linear speed associated with the homogeneous state around the position of the front. We complement our study with the construction of strictly monotone traveling front solutions with strong exponential decay near the unstable state when the profile of the diffusion coefficient is decreasing and in the regime where the forcing speed is precisely the selected spreading speed.
{"title":"Asymptotic spreading for Fisher-KPP reaction-diffusion equations with heterogeneous shifting diffusivity","authors":"Grégory Faye, T. Giletti, Matt Holzer","doi":"10.3934/dcdss.2021146","DOIUrl":"https://doi.org/10.3934/dcdss.2021146","url":null,"abstract":"We determine the asymptotic spreading speed of the solutions of a Fisher-KPP reaction-diffusion equation, starting from compactly supported initial data, when the diffusion coefficient is a fixed bounded monotone profile that is shifted at a given forcing speed and satisfies a general uniform ellipticity condition. Depending on the monotonicity of the profile, we are able to characterize this spreading speed as a function of the forcing speed and the two linear spreading speeds associated to the asymptotic problems at begin{document}$ x = pm infty $end{document}. Most notably, when the profile of the diffusion coefficient is increasing we show that there is an intermediate range for the forcing speed where spreading actually occurs at a speed which is larger than the linear speed associated with the homogeneous state around the position of the front. We complement our study with the construction of strictly monotone traveling front solutions with strong exponential decay near the unstable state when the profile of the diffusion coefficient is decreasing and in the regime where the forcing speed is precisely the selected spreading speed.","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89816030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Any begin{document}$ C^d $end{document} conservative map begin{document}$ f $end{document} of the begin{document}$ d $end{document}-dimensional unit ball begin{document}$ {mathbb B}^d $end{document}, begin{document}$ dgeq 2 $end{document}, can be realized by renormalized iteration of a begin{document}$ C^d $end{document} perturbation of identity: there exists a conservative diffeomorphism of begin{document}$ {mathbb B}^d $end{document}, arbitrarily close to identity in the begin{document}$ C^d $end{document} topology, that has a periodic disc on which the return dynamics after a begin{document}$ C^d $end{document} change of coordinates is exactly begin{document}$ f $end{document}.
Any begin{document}$ C^d $end{document} conservative map begin{document}$ f $end{document} of the begin{document}$ d $end{document}-dimensional unit ball begin{document}$ {mathbb B}^d $end{document}, begin{document}$ dgeq 2 $end{document}, can be realized by renormalized iteration of a begin{document}$ C^d $end{document} perturbation of identity: there exists a conservative diffeomorphism of begin{document}$ {mathbb B}^d $end{document}, arbitrarily close to identity in the begin{document}$ C^d $end{document} topology, that has a periodic disc on which the return dynamics after a begin{document}$ C^d $end{document} change of coordinates is exactly begin{document}$ f $end{document}.
{"title":"Realizing arbitrary $d$-dimensional dynamics by renormalization of $C^d$-perturbations of identity","authors":"B. Fayad, M. Saprykina","doi":"10.3934/dcds.2021129","DOIUrl":"https://doi.org/10.3934/dcds.2021129","url":null,"abstract":"<p style='text-indent:20px;'>Any <inline-formula><tex-math id=\"M3\">begin{document}$ C^d $end{document}</tex-math></inline-formula> conservative map <inline-formula><tex-math id=\"M4\">begin{document}$ f $end{document}</tex-math></inline-formula> of the <inline-formula><tex-math id=\"M5\">begin{document}$ d $end{document}</tex-math></inline-formula>-dimensional unit ball <inline-formula><tex-math id=\"M6\">begin{document}$ {mathbb B}^d $end{document}</tex-math></inline-formula>, <inline-formula><tex-math id=\"M7\">begin{document}$ dgeq 2 $end{document}</tex-math></inline-formula>, can be realized by renormalized iteration of a <inline-formula><tex-math id=\"M8\">begin{document}$ C^d $end{document}</tex-math></inline-formula> perturbation of identity: there exists a conservative diffeomorphism of <inline-formula><tex-math id=\"M9\">begin{document}$ {mathbb B}^d $end{document}</tex-math></inline-formula>, arbitrarily close to identity in the <inline-formula><tex-math id=\"M10\">begin{document}$ C^d $end{document}</tex-math></inline-formula> topology, that has a periodic disc on which the return dynamics after a <inline-formula><tex-math id=\"M11\">begin{document}$ C^d $end{document}</tex-math></inline-formula> change of coordinates is exactly <inline-formula><tex-math id=\"M12\">begin{document}$ f $end{document}</tex-math></inline-formula>.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"420 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75769252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the problem of recovering the initial condition in the one-dimensional one-phase Stefan problem for the heat equation from the knowledge of the position of the melting point. We first recall some properties of the free boundary solution. Then we study the uniqueness and stability of the inversion. The principal contribution of the paper is a new logarithmic type stability estimate that shows that the inversion may be severely ill-posed. The proof is based on integral equations representation techniques, and the unique continuation property for parabolic type solutions. We also present few numerical examples operating with noisy synthetic data.
{"title":"Recovering the initial condition in the one-phase Stefan problem","authors":"Chifaa Ghanmi, S. Aouadi, Faouzi Triki","doi":"10.3934/dcdss.2021087","DOIUrl":"https://doi.org/10.3934/dcdss.2021087","url":null,"abstract":"We consider the problem of recovering the initial condition in the one-dimensional one-phase Stefan problem for the heat equation from the knowledge of the position of the melting point. We first recall some properties of the free boundary solution. Then we study the uniqueness and stability of the inversion. The principal contribution of the paper is a new logarithmic type stability estimate that shows that the inversion may be severely ill-posed. The proof is based on integral equations representation techniques, and the unique continuation property for parabolic type solutions. We also present few numerical examples operating with noisy synthetic data.","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"51 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90051431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A set begin{document}$ E subset mathbb{N} $end{document} is an interpolation set for nilsequences if every bounded function on begin{document}$ E $end{document} can be extended to a nilsequence on begin{document}$ mathbb{N} $end{document}. Following a theorem of Strzelecki, every lacunary set is an interpolation set for nilsequences. We show that sublacunary sets are not interpolation sets for nilsequences. Here begin{document}$ {r_n: n in mathbb{N}} subset mathbb{N} $end{document} with begin{document}$ r_1 < r_2 < ldots $end{document} is sublacunary if begin{document}$ lim_{n to infty} (log r_n)/n = 0 $end{document}. Furthermore, we prove that the union of an interpolation set for nilsequences and a finite set is an interpolation set for nilsequences. Lastly, we provide a new class of interpolation sets for Bohr almost periodic sequences, and as a result, obtain a new example of interpolation set for begin{document}$ 2 $end{document}-step nilsequences which is not an interpolation set for Bohr almost periodic sequences.
A set begin{document}$ E subset mathbb{N} $end{document} is an interpolation set for nilsequences if every bounded function on begin{document}$ E $end{document} can be extended to a nilsequence on begin{document}$ mathbb{N} $end{document}. Following a theorem of Strzelecki, every lacunary set is an interpolation set for nilsequences. We show that sublacunary sets are not interpolation sets for nilsequences. Here begin{document}$ {r_n: n in mathbb{N}} subset mathbb{N} $end{document} with begin{document}$ r_1 < r_2 < ldots $end{document} is sublacunary if begin{document}$ lim_{n to infty} (log r_n)/n = 0 $end{document}. Furthermore, we prove that the union of an interpolation set for nilsequences and a finite set is an interpolation set for nilsequences. Lastly, we provide a new class of interpolation sets for Bohr almost periodic sequences, and as a result, obtain a new example of interpolation set for begin{document}$ 2 $end{document}-step nilsequences which is not an interpolation set for Bohr almost periodic sequences.
{"title":"Sublacunary sets and interpolation sets for nilsequences","authors":"Anh N. Le","doi":"10.3934/dcds.2021175","DOIUrl":"https://doi.org/10.3934/dcds.2021175","url":null,"abstract":"<p style='text-indent:20px;'>A set <inline-formula><tex-math id=\"M1\">begin{document}$ E subset mathbb{N} $end{document}</tex-math></inline-formula> is an interpolation set for nilsequences if every bounded function on <inline-formula><tex-math id=\"M2\">begin{document}$ E $end{document}</tex-math></inline-formula> can be extended to a nilsequence on <inline-formula><tex-math id=\"M3\">begin{document}$ mathbb{N} $end{document}</tex-math></inline-formula>. Following a theorem of Strzelecki, every lacunary set is an interpolation set for nilsequences. We show that sublacunary sets are not interpolation sets for nilsequences. Here <inline-formula><tex-math id=\"M4\">begin{document}$ {r_n: n in mathbb{N}} subset mathbb{N} $end{document}</tex-math></inline-formula> with <inline-formula><tex-math id=\"M5\">begin{document}$ r_1 < r_2 < ldots $end{document}</tex-math></inline-formula> is <i>sublacunary</i> if <inline-formula><tex-math id=\"M6\">begin{document}$ lim_{n to infty} (log r_n)/n = 0 $end{document}</tex-math></inline-formula>. Furthermore, we prove that the union of an interpolation set for nilsequences and a finite set is an interpolation set for nilsequences. Lastly, we provide a new class of interpolation sets for Bohr almost periodic sequences, and as a result, obtain a new example of interpolation set for <inline-formula><tex-math id=\"M7\">begin{document}$ 2 $end{document}</tex-math></inline-formula>-step nilsequences which is not an interpolation set for Bohr almost periodic sequences.</p>","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89024961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we find curves minimizing the elastic energy among curves whose length is fixed and whose ends are pinned. Applying the shooting method, we can identify all critical points explicitly and determine which curve is the global minimizer. As a result we show that the critical points consist of wavelike elasticae and the minimizers do not have any loops or interior inflection points.
{"title":"The critical points of the elastic energy among curves pinned at endpoints","authors":"Kensuke Yoshizawa","doi":"10.3934/dcds.2021122","DOIUrl":"https://doi.org/10.3934/dcds.2021122","url":null,"abstract":"In this paper we find curves minimizing the elastic energy among curves whose length is fixed and whose ends are pinned. Applying the shooting method, we can identify all critical points explicitly and determine which curve is the global minimizer. As a result we show that the critical points consist of wavelike elasticae and the minimizers do not have any loops or interior inflection points.","PeriodicalId":11254,"journal":{"name":"Discrete & Continuous Dynamical Systems - S","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75682271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}