Multibubble analysis on N-Laplace equation in {\mathbb{R}^N}

In this note, we describe the asymptotic behavior of sequences of solutions to N-Laplace equations with critical exponential growth in smooth bounded domain in ${\mathbb{R}^N}$ . Precisely we prove multibubble phenomena and obtain an energy inequality for those concentrating solutions. In fact we partly extend the corresponding two-dimensional results of Adimurthi and Struwe (J Funct Anal 175:125?C167, 2000) and Druet (Duke Math J 132:217?C269, 2006) to high dimensional case.     

Global attractor for a semilinear strongly degenerate parabolic equation on {\mathbb{R}^N}

The aim of this paper is to prove the existence of the global attractor for a semilinear strongly degenerate parabolic equation on \({\mathbb{R}^N}\) with the locally Lipschitz nonlinearity satisfying a subcritical growth condition.     

A smooth global branch of solutions for a semilinear elliptic equation on {\mathbb{R}^N}

The existence of a global branch of positive spherically symmetric solutions ${\{(\lambda,u(\lambda)):\lambda\in(0,\infty)\}}$ of the semilinear elliptic equation $$\Delta u - \lambda u + V(x)|u|^{p-1}u = 0 \quad \text{in}\,\mathbb{R}^N\,\text{with}\,N\geq3$$ is proved for ${1 < p < 1+\frac{4-2b}{N-2}}$ , where ${b\in(0,2)}$ is such that the radial function V vanishes at infinity like |x|^?b . V is allowed to be singular at the origin but not worse than |x|^?b . The mapping ${\lambda\mapsto u(\lambda)}$ is of class ${C^r((0,\infty),H^1(\mathbb{R}^N))}$ if ${V\in C^r(\mathbb{R}^N\setminus\{0\},\mathbb{R})}$ , for r = 0, 1. Further properties of regularity and decay at infinity of solutions are also established. This work is a natural continuation of previous results by Stuart and the author, concerning the existence of a local branch of solutions of the same equation for values of the bifurcation parameter λ in a right neighbourhood of λ = 0. The variational structure of the equation is deeply exploited and the global continuation is obtained via an implicit function theorem.     

Existence of solutions for a perturbation sublinear elliptic equation in {\mathbb {R}^N}

In this paper we consider the following problem $\left\{\begin{array}{l} -\Delta u=u-\left|u\right|^{-2\theta}u+f \\u \in H^1(\mathbb{R}^N)\cap L^{2(1-\theta)}(\mathbb{R}^N)\end{array}\right.$ ${f \in L^2(\mathbb{R}^N)\cap L^\frac{2(1-\theta)}{1-2\theta}(\mathbb{R}^N),\, N\geq 3,\, f\geq 0,\, f \neq 0}In this paper we consider the following problem

{l -Du=u-|u|-2qu+f u ? H1(\mathbbRN)?L2(1-q)(\mathbbRN)\left\{\begin{array}{l} -\Delta u=u-\left|u\right|^{-2\theta}u+f \\u \in H^1(\mathbb{R}^N)\cap L^{2(1-\theta)}(\mathbb{R}^N)\end{array}\right.      5. A note on uniqueness of entropy solutions to degenerate parabolic equations in {\mathbb{R}^N}      Boris Andreianov  Mohamed Maliki 《NoDEA : Nonlinear Differential Equations and Applications》2010,17(1):109-118 We study the Cauchy problem in \mathbbRN{\mathbb{R}^N} for the parabolic equation ut+div F(u)=Dj(u),u_t+{\rm div}\,F(u)=\Delta\varphi(u),      6. Complexity of asymptotic behavior of the porous medium equation in {\mathbb{R}^N}      Jingxue Yin  Liangwei Wang  Rui Huang 《Journal of Evolution Equations》2011,11(2):429-455       7. Multiple solutions for a superlinear and periodic elliptic system on $${\mathbb{R}^N}$$      Fukun Zhao  Leiga Zhao  Yanheng Ding 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2011,62(3):495-511 This paper is concerned with the following periodic Hamiltonian elliptic system $$\left \{\begin{array}{l}-\Delta u+V(x)u=g(x,v)\, {\rm in }\,\mathbb{R}^N,\\-\Delta v+V(x)v=f(x,u)\, {\rm in }\, \mathbb{R}^N,\\ u(x)\to 0\, {\rm and}\,v(x)\to0\, {\rm as }\,|x|\to\infty,\end{array}\right.$$ where the potential V is periodic and 0 lies in a gap of the spectrum of ?Δ + V, f(x, t) and g(x, t) depend periodically on x and are superlinear but subcritical in t at infinity. By establishing a variational setting, existence of a ground state solution and multiple solution for odd f and g are obtained.       8. A minimum principle for the problem of St-Venant in {\mathbb{R}^N, N \geq 2}      G. A. Philippin  V. Proytcheva 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2012,63(6):1085-1090 This paper deals mainly with the St-Venant problem in a convex domain ?? of ${\mathbb{R}^N, N \geq 2}$ . A minimum principle for a combination of the stress function ${\psi}$ and ${|\nabla \psi|}$ is derived. Some possible applications are indicated.      9. Exact multiplicity for the perturbed Q-curvature problem in {\mathbb{R}^N,N \geq 5}      Abhishek Sarkar  S. Prashanth 《Archiv der Mathematik》2014,102(6):575-587 Let N ≥ 5 and \({{\mathcal{D}}^{2,2} (\mathbb{R}^N)}\) denote the closure of \({C_0^\infty (\mathbb{R}^N)}\) in the norm \({\|u\|_{{\mathcal{D}}^{2,2} (\mathbb{R}^N)}^2 := \int\nolimits_{\mathbb{R}^N} |\Delta u|^2.}\) Let \({K \in C^2 (\mathbb{R}^N).}\) We consider the following problem for ? ≥ 0: $$(P_\varepsilon) \left\{\begin{array}{llll}{\rm Find} \, u \in {\mathcal{D}}^{2, 2} (\mathbb{R}^N) \, \, {\rm solving} :\\ \left.\begin{array}{lll}\Delta^2 u = (1+ \varepsilon K (x)) u^{\frac{N+4}{N-4}}\\ u > 0 \end{array}\right\}{\rm in} \, \mathbb{R}^N.\end{array}\right.$$ We show an exact multiplicity result for (P ? ) for all small ? > 0.      10. Singular oscillatory integrals on {\mathbb{R}^n}      M. Papadimitrakis  I. R. Parissis 《Mathematische Zeitschrift》2010,266(1):169-179 Let ${\mathcal{P}_{d,n}}Let Pd,n{\mathcal{P}_{d,n}} denote the space of all real polynomials of degree at most d on \mathbbRn{\mathbb{R}^n} . We prove a new estimate for the logarithmic measure of the sublevel set of a polynomial P ? Pd,1{P\in \mathcal{P}_{d,1}} . Using this estimate, we prove that supP ? Pd,n| p.v.ò\mathbbRneiP(x)\fracW(x/|x|)|x|ndx| ￡ c log d (||W||L logL(Sn-1)+1),\mathop{\rm sup}\limits_ {P \in \mathcal{P}_{d,n}}\left| p.v.\int_{\mathbb{R}^{n}}{e^{iP(x)}}{\frac{\Omega(x/|x|)}{|x|^n}dx}\right | \leq c\,{\rm log}\,d\,(||\Omega||_L \log L(S^{n-1})+1),      11. Some remarks on systems of elliptic equations doubly critical in the whole $${\mathbb{R}^N}$$      Boumediene Abdellaoui  Veronica Felli  Ireneo Peral 《Calculus of Variations and Partial Differential Equations》2009,34(1):97-137 We study the existence of different types of positive solutions to problem where , , and is the critical Sobolev exponent. A careful analysis of the behavior of Palais-Smale sequences is performed to recover compactness for some ranges of energy levels and to prove the existence of ground state solutions and mountain pass critical points of the associated functional on the Nehari manifold. A variational perturbative method is also used to study the existence of a non trivial manifold of positive solutions which bifurcates from the manifold of solutions to the uncoupled system corresponding to the unperturbed problem obtained for ν = 0. B. Abdellaoui and I. Peral supported by projects MTM2007-65018, MEC and CCG06-UAM/ESP-0340, Spain. V. Felli supported by Italy MIUR, national project Variational Methods and Nonlinear Differential Equations.      12. A Note on the Tight Spherical 7-Design in {\mathbb R}^{23} and 5-Design in {\mathbb R}^{7*}      Hans Cuypers 《Designs, Codes and Cryptography》2005,34(2-3):333-337 In this note we prove the uniqueness of the tight spherical 7-design in consisting of 4600 vectors and with automorphism group 2 × Co2 as well as the uniqueness of the tight spherical 5-design in on 112 vectors and with automorphism group 2 × Sp6(2).To the memory of Jaap Seidel      13. A supersolution-subsolution method for nonlinear biharmonic equations in \mathbb{R}^N      Yasuhiro Furusho  Kusano Takaŝi 《Czechoslovak Mathematical Journal》1997,47(4):749-768       14. Multiplicity of solutions for differential inclusion problems in {\mathbb{R}^N} involving the p(x)-Laplacian      Bin Ge  Qing-Mei Zhou  Xiao-Ping Xue 《Monatshefte für Mathematik》2012,168(3-4):363-380 In this paper we consider the differential inclusion problem in ${\mathbb{R}^N}$ involving the p(x)-Laplacian of the type $$ -\triangle_{p(x)} u+V(x)|u|^{p(x)-2}u\in \partial F(x,u)\,\,\,{\rm in}\, \mathbb{R}^N. $$ The approach used in this paper is the variational method for locally Lipschitz functions. More precisely, based on the Weirstrass Theorem and Mountain Pass Theorem, we get there exist at least two nontrivial solutions. We also establish a Bartsch–Wang type compact embedding theorem for variable exponent spaces.      15. On the Rao modules of minimal curves in $${\mathbb{P}^N}$$      Roberta Di Gennaro 《Ricerche di matematica》2009,58(2):249-262 We study the Hartshorne-Rao modules M C of minimal curves C in \mathbbPN{\mathbb{P}^N} , with N ≥ 4, lying in the same liaison class of curves on a smooth rational scroll surface. We get a free minimal resolution of M C for some of such curves and an upper bound for Betti numbers of M C , for any C.      16. On Quadratic Differentials and Twisted Normal Maps of Surfaces in {\mathbb{S}^{2} \times\mathbb{R}} and {\mathbb{H}^{2} \times\mathbb{R}}      Maria Luiza Leite  Jaime Ripoll 《Results in Mathematics》2011,60(1-4):351-360 Given a Lie group G with a bi-invariant metric and a compact Lie subgroup K, Bittencourt and Ripoll used the homogeneous structure of quotient spaces to define a Gauss map ${\mathcal{N}:M^{n}\rightarrow{\mathbb{S}}}$ on any hypersupersurface ${M^{n}\looparrowright G/K}$ , where ${{\mathbb{S}}}$ is the unit sphere of the Lie algebra of G. It is proved in Bittencourt and Ripoll (Pacific J Math 224:45–64, 2006) that M n having constant mean curvature (CMC) is equivalent to ${\mathcal{N}}$ being harmonic, a generalization of a Ruh–Vilms theorem for submanifolds in the Euclidean space. In particular, when n = 2, the induced quadratic differential ${\mathcal{Q}_{\mathcal{N}}:=(\mathcal{N}^{\ast}g)^{2,0}}$ is holomorphic on CMC surfaces of G/K. In this paper, we take ${G/K={\mathbb{S}}^{2}\times{\mathbb{R}}}$ and compare ${\mathcal{Q}_{\mathcal{N}}}$ with the Abresch–Rosenberg differential ${\mathcal{Q}}$ , also holomorphic for CMC surfaces. It is proved that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ , after showing that ${\mathcal{N}}$ is the twisted normal given by (1.5) herein. Then we define the twisted normal for surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ and prove that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ as well. Within the unified model for the two product spaces, we compute the tension field of ${\mathcal{N}}$ and extend to surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ the equivalence between the CMC property and the harmonicity of ${\mathcal{N}.}$       17. Branches of solutions to semilinear elliptic equations on mathbb{R}^N      H. Jeanjean  M. Lucia  C.A. Stuart 《Mathematische Zeitschrift》1999,230(1):79-105 For a large class of functions f, we consider the nonlinear elliptic eigenvalue problem We describe the behaviour of the branch of solutions emanating from an eigenvalue of odd multiplicity below the essential spectrum of the linearized problem. A sharper result is obtained in the case of the lowest eigenvalue. The discussion is based on the degree theory for proper Fredholm maps developed by P.M Fitzpatrick, J. Pejsachowicz and P.J. Rabier. Received November 13, 1996; in final form March 24, 1997      18. Isometric Immersions into {\mathbb{S}^m \times \mathbb{R}} and {\mathbb{H}^m \times \mathbb{R}} with High Codimensions      Qun Chen  Qing Cui 《Results in Mathematics》2010,57(3-4):319-333 In this paper, we obtain sufficient and necessary conditions for a simply connected Riemannian manifold (M n , g) to be isometrically immersed into ${\mathbb{S}^m \times \mathbb{R}}$ and ${\mathbb{H}^m \times \mathbb{R}}$ .      19. Approximations for two variants of the Steiner tree problem in the Euclidean plane {\mathbb{R}^2}      Jianping Li  Haiyan Wang  Binchao Huang  Junran Lichen 《Journal of Global Optimization》2013,57(3):783-801 Given n terminals in the Euclidean plane and a positive constant l, find a Steiner tree T interconnecting all terminals with the minimum total cost of Steiner points and a specific material used to construct all edges in T such that the Euclidean length of each edge in T is no more than l. In this paper, according to the cost b of each Steiner point and the different costs of some specific materials with the different lengths, we study two variants of the Steiner tree problem in the Euclidean plane as follows: (1) If a specific material to construct all edges in such a Steiner tree has its infinite length and the cost of per unit length of such a specific material used is c 1, the objective is to minimize the total cost of the Steiner points and such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_1+ c_1 \cdot \sum_{e \in T} w(e)\}}$ , where T is a Steiner tree constructed, k 1 is the number of Steiner points and w(e) is the length of part cut from such a specific material to construct edge e in T, and we call this version as the minimum-cost Steiner points and edges problem (MCSPE, for short). (2) If a specific material to construct all edges in such a Steiner tree has its finite length L (l ≤ L) and the cost of per piece of such a specific material used is c 2, the objective is to minimize the total cost of the Steiner points and the pieces of such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_2+ c_2 \cdot k_3\}}$ , where T is a Steiner tree constructed, k 2 is the number of Steiner points in T and k 3 is the number of pieces of such a specific material used, and we call this version as the minimum-cost Steiner points and pieces of specific material problem (MCSPPSM, for short). These two variants of the Steiner tree problem are NP-hard with some applications in VLSI design, WDM optical networks and wireless communications. In this paper, we first design an approximation algorithm with performance ratio 3 for the MCSPE problem, and then present two approximation algorithms with performance ratios 4 and 3.236 for the MCSPPSM problem, respectively.      20. Approximation of Holomorphic Functions on Compact Subsets of mathbb {R}^N      Rafał Pierzchała 《Constructive Approximation》2015,41(1):133-155       设为首页 | 免责声明 | 关于勤云 | 加入收藏 Copyright©北京勤云科技发展有限公司  京ICP备09084417号

A note on uniqueness of entropy solutions to degenerate parabolic equations in {\mathbb{R}^N}

We study the Cauchy problem in \mathbbR^N{\mathbb{R}^N} for the parabolic equation

Multiple solutions for a superlinear and periodic elliptic system on $${\mathbb{R}^N}$$

This paper is concerned with the following periodic Hamiltonian elliptic system

$$\left \{\begin{array}{l}-\Delta u+V(x)u=g(x,v)\, {\rm in }\,\mathbb{R}^N,\\-\Delta v+V(x)v=f(x,u)\, {\rm in }\, \mathbb{R}^N,\\ u(x)\to 0\, {\rm and}\,v(x)\to0\, {\rm as }\,|x|\to\infty,\end{array}\right.$$

where the potential V is periodic and 0 lies in a gap of the spectrum of ?Δ + V, f(x, t) and g(x, t) depend periodically on x and are superlinear but subcritical in t at infinity. By establishing a variational setting, existence of a ground state solution and multiple solution for odd f and g are obtained.

     

A minimum principle for the problem of St-Venant in {\mathbb{R}^N, N \geq 2}

This paper deals mainly with the St-Venant problem in a convex domain ?? of ${\mathbb{R}^N, N \geq 2}$ . A minimum principle for a combination of the stress function ${\psi}$ and ${|\nabla \psi|}$ is derived. Some possible applications are indicated.     

Exact multiplicity for the perturbed Q-curvature problem in {\mathbb{R}^N,N \geq 5}

Let N ≥ 5 and \({{\mathcal{D}}^{2,2} (\mathbb{R}^N)}\) denote the closure of \({C_0^\infty (\mathbb{R}^N)}\) in the norm \({\|u\|_{{\mathcal{D}}^{2,2} (\mathbb{R}^N)}^2 := \int\nolimits_{\mathbb{R}^N} |\Delta u|^2.}\) Let \({K \in C^2 (\mathbb{R}^N).}\) We consider the following problem for ? ≥ 0: $$(P_\varepsilon) \left\{\begin{array}{llll}{\rm Find} \, u \in {\mathcal{D}}^{2, 2} (\mathbb{R}^N) \, \, {\rm solving} :\\ \left.\begin{array}{lll}\Delta^2 u = (1+ \varepsilon K (x)) u^{\frac{N+4}{N-4}}\\ u > 0 \end{array}\right\}{\rm in} \, \mathbb{R}^N.\end{array}\right.$$ We show an exact multiplicity result for (P _? ) for all small ? > 0.     

Singular oscillatory integrals on {\mathbb{R}^n}

Let ${\mathcal{P}_{d,n}}Let P_d,n{\mathcal{P}_{d,n}} denote the space of all real polynomials of degree at most d on \mathbbRⁿ{\mathbb{R}^n} . We prove a new estimate for the logarithmic measure of the sublevel set of a polynomial P ? P_d,1{P\in \mathcal{P}_{d,1}} . Using this estimate, we prove that

supP ? Pd,n| p.v.ò\mathbbRneiP(x)\fracW(x/|x|)|x|ndx| ￡ c log d (||W||L logL(Sn-1)+1),\mathop{\rm sup}\limits_ {P \in \mathcal{P}_{d,n}}\left| p.v.\int_{\mathbb{R}^{n}}{e^{iP(x)}}{\frac{\Omega(x/|x|)}{|x|^n}dx}\right | \leq c\,{\rm log}\,d\,(||\Omega||_L \log L(S^{n-1})+1),      11. Some remarks on systems of elliptic equations doubly critical in the whole $${\mathbb{R}^N}$$      Boumediene Abdellaoui  Veronica Felli  Ireneo Peral 《Calculus of Variations and Partial Differential Equations》2009,34(1):97-137 We study the existence of different types of positive solutions to problem where , , and is the critical Sobolev exponent. A careful analysis of the behavior of Palais-Smale sequences is performed to recover compactness for some ranges of energy levels and to prove the existence of ground state solutions and mountain pass critical points of the associated functional on the Nehari manifold. A variational perturbative method is also used to study the existence of a non trivial manifold of positive solutions which bifurcates from the manifold of solutions to the uncoupled system corresponding to the unperturbed problem obtained for ν = 0. B. Abdellaoui and I. Peral supported by projects MTM2007-65018, MEC and CCG06-UAM/ESP-0340, Spain. V. Felli supported by Italy MIUR, national project Variational Methods and Nonlinear Differential Equations.      12. A Note on the Tight Spherical 7-Design in {\mathbb R}^{23} and 5-Design in {\mathbb R}^{7*}      Hans Cuypers 《Designs, Codes and Cryptography》2005,34(2-3):333-337 In this note we prove the uniqueness of the tight spherical 7-design in consisting of 4600 vectors and with automorphism group 2 × Co2 as well as the uniqueness of the tight spherical 5-design in on 112 vectors and with automorphism group 2 × Sp6(2).To the memory of Jaap Seidel      13. A supersolution-subsolution method for nonlinear biharmonic equations in \mathbb{R}^N      Yasuhiro Furusho  Kusano Takaŝi 《Czechoslovak Mathematical Journal》1997,47(4):749-768       14. Multiplicity of solutions for differential inclusion problems in {\mathbb{R}^N} involving the p(x)-Laplacian      Bin Ge  Qing-Mei Zhou  Xiao-Ping Xue 《Monatshefte für Mathematik》2012,168(3-4):363-380 In this paper we consider the differential inclusion problem in ${\mathbb{R}^N}$ involving the p(x)-Laplacian of the type $$ -\triangle_{p(x)} u+V(x)|u|^{p(x)-2}u\in \partial F(x,u)\,\,\,{\rm in}\, \mathbb{R}^N. $$ The approach used in this paper is the variational method for locally Lipschitz functions. More precisely, based on the Weirstrass Theorem and Mountain Pass Theorem, we get there exist at least two nontrivial solutions. We also establish a Bartsch–Wang type compact embedding theorem for variable exponent spaces.      15. On the Rao modules of minimal curves in $${\mathbb{P}^N}$$      Roberta Di Gennaro 《Ricerche di matematica》2009,58(2):249-262 We study the Hartshorne-Rao modules M C of minimal curves C in \mathbbPN{\mathbb{P}^N} , with N ≥ 4, lying in the same liaison class of curves on a smooth rational scroll surface. We get a free minimal resolution of M C for some of such curves and an upper bound for Betti numbers of M C , for any C.      16. On Quadratic Differentials and Twisted Normal Maps of Surfaces in {\mathbb{S}^{2} \times\mathbb{R}} and {\mathbb{H}^{2} \times\mathbb{R}}      Maria Luiza Leite  Jaime Ripoll 《Results in Mathematics》2011,60(1-4):351-360 Given a Lie group G with a bi-invariant metric and a compact Lie subgroup K, Bittencourt and Ripoll used the homogeneous structure of quotient spaces to define a Gauss map ${\mathcal{N}:M^{n}\rightarrow{\mathbb{S}}}$ on any hypersupersurface ${M^{n}\looparrowright G/K}$ , where ${{\mathbb{S}}}$ is the unit sphere of the Lie algebra of G. It is proved in Bittencourt and Ripoll (Pacific J Math 224:45–64, 2006) that M n having constant mean curvature (CMC) is equivalent to ${\mathcal{N}}$ being harmonic, a generalization of a Ruh–Vilms theorem for submanifolds in the Euclidean space. In particular, when n = 2, the induced quadratic differential ${\mathcal{Q}_{\mathcal{N}}:=(\mathcal{N}^{\ast}g)^{2,0}}$ is holomorphic on CMC surfaces of G/K. In this paper, we take ${G/K={\mathbb{S}}^{2}\times{\mathbb{R}}}$ and compare ${\mathcal{Q}_{\mathcal{N}}}$ with the Abresch–Rosenberg differential ${\mathcal{Q}}$ , also holomorphic for CMC surfaces. It is proved that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ , after showing that ${\mathcal{N}}$ is the twisted normal given by (1.5) herein. Then we define the twisted normal for surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ and prove that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ as well. Within the unified model for the two product spaces, we compute the tension field of ${\mathcal{N}}$ and extend to surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ the equivalence between the CMC property and the harmonicity of ${\mathcal{N}.}$       17. Branches of solutions to semilinear elliptic equations on mathbb{R}^N      H. Jeanjean  M. Lucia  C.A. Stuart 《Mathematische Zeitschrift》1999,230(1):79-105 For a large class of functions f, we consider the nonlinear elliptic eigenvalue problem We describe the behaviour of the branch of solutions emanating from an eigenvalue of odd multiplicity below the essential spectrum of the linearized problem. A sharper result is obtained in the case of the lowest eigenvalue. The discussion is based on the degree theory for proper Fredholm maps developed by P.M Fitzpatrick, J. Pejsachowicz and P.J. Rabier. Received November 13, 1996; in final form March 24, 1997      18. Isometric Immersions into {\mathbb{S}^m \times \mathbb{R}} and {\mathbb{H}^m \times \mathbb{R}} with High Codimensions      Qun Chen  Qing Cui 《Results in Mathematics》2010,57(3-4):319-333 In this paper, we obtain sufficient and necessary conditions for a simply connected Riemannian manifold (M n , g) to be isometrically immersed into ${\mathbb{S}^m \times \mathbb{R}}$ and ${\mathbb{H}^m \times \mathbb{R}}$ .      19. Approximations for two variants of the Steiner tree problem in the Euclidean plane {\mathbb{R}^2}      Jianping Li  Haiyan Wang  Binchao Huang  Junran Lichen 《Journal of Global Optimization》2013,57(3):783-801 Given n terminals in the Euclidean plane and a positive constant l, find a Steiner tree T interconnecting all terminals with the minimum total cost of Steiner points and a specific material used to construct all edges in T such that the Euclidean length of each edge in T is no more than l. In this paper, according to the cost b of each Steiner point and the different costs of some specific materials with the different lengths, we study two variants of the Steiner tree problem in the Euclidean plane as follows: (1) If a specific material to construct all edges in such a Steiner tree has its infinite length and the cost of per unit length of such a specific material used is c 1, the objective is to minimize the total cost of the Steiner points and such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_1+ c_1 \cdot \sum_{e \in T} w(e)\}}$ , where T is a Steiner tree constructed, k 1 is the number of Steiner points and w(e) is the length of part cut from such a specific material to construct edge e in T, and we call this version as the minimum-cost Steiner points and edges problem (MCSPE, for short). (2) If a specific material to construct all edges in such a Steiner tree has its finite length L (l ≤ L) and the cost of per piece of such a specific material used is c 2, the objective is to minimize the total cost of the Steiner points and the pieces of such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_2+ c_2 \cdot k_3\}}$ , where T is a Steiner tree constructed, k 2 is the number of Steiner points in T and k 3 is the number of pieces of such a specific material used, and we call this version as the minimum-cost Steiner points and pieces of specific material problem (MCSPPSM, for short). These two variants of the Steiner tree problem are NP-hard with some applications in VLSI design, WDM optical networks and wireless communications. In this paper, we first design an approximation algorithm with performance ratio 3 for the MCSPE problem, and then present two approximation algorithms with performance ratios 4 and 3.236 for the MCSPPSM problem, respectively.      20. Approximation of Holomorphic Functions on Compact Subsets of mathbb {R}^N      Rafał Pierzchała 《Constructive Approximation》2015,41(1):133-155

Some remarks on systems of elliptic equations doubly critical in the whole $${\mathbb{R}^N}$$

We study the existence of different types of positive solutions to problem

A Note on the Tight Spherical 7-Design in {\mathbb R}^{23} and 5-Design in {\mathbb R}^{7*}

In this note we prove the uniqueness of the tight spherical 7-design in consisting of 4600 vectors and with automorphism group 2 × Co₂ as well as the uniqueness of the tight spherical 5-design in on 112 vectors and with automorphism group 2 × Sp₆(2).To the memory of Jaap Seidel     

Multiplicity of solutions for differential inclusion problems in {\mathbb{R}^N} involving the p(x)-Laplacian

In this paper we consider the differential inclusion problem in ${\mathbb{R}^N}$ involving the p(x)-Laplacian of the type $$ -\triangle_{p(x)} u+V(x)|u|^{p(x)-2}u\in \partial F(x,u)\,\,\,{\rm in}\, \mathbb{R}^N. $$ The approach used in this paper is the variational method for locally Lipschitz functions. More precisely, based on the Weirstrass Theorem and Mountain Pass Theorem, we get there exist at least two nontrivial solutions. We also establish a Bartsch–Wang type compact embedding theorem for variable exponent spaces.     

On the Rao modules of minimal curves in $${\mathbb{P}^N}$$

We study the Hartshorne-Rao modules M _C of minimal curves C in \mathbbP^N{\mathbb{P}^N} , with N ≥ 4, lying in the same liaison class of curves on a smooth rational scroll surface. We get a free minimal resolution of M _C for some of such curves and an upper bound for Betti numbers of M _C , for any C.     

On Quadratic Differentials and Twisted Normal Maps of Surfaces in {\mathbb{S}^{2} \times\mathbb{R}} and {\mathbb{H}^{2} \times\mathbb{R}}

Given a Lie group G with a bi-invariant metric and a compact Lie subgroup K, Bittencourt and Ripoll used the homogeneous structure of quotient spaces to define a Gauss map ${\mathcal{N}:M^{n}\rightarrow{\mathbb{S}}}$ on any hypersupersurface ${M^{n}\looparrowright G/K}$ , where ${{\mathbb{S}}}$ is the unit sphere of the Lie algebra of G. It is proved in Bittencourt and Ripoll (Pacific J Math 224:45–64, 2006) that M ⁿ having constant mean curvature (CMC) is equivalent to ${\mathcal{N}}$ being harmonic, a generalization of a Ruh–Vilms theorem for submanifolds in the Euclidean space. In particular, when n = 2, the induced quadratic differential ${\mathcal{Q}_{\mathcal{N}}:=(\mathcal{N}^{\ast}g)^{2,0}}$ is holomorphic on CMC surfaces of G/K. In this paper, we take ${G/K={\mathbb{S}}^{2}\times{\mathbb{R}}}$ and compare ${\mathcal{Q}_{\mathcal{N}}}$ with the Abresch–Rosenberg differential ${\mathcal{Q}}$ , also holomorphic for CMC surfaces. It is proved that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ , after showing that ${\mathcal{N}}$ is the twisted normal given by (1.5) herein. Then we define the twisted normal for surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ and prove that ${\mathcal{Q}=\mathcal{Q}_{\mathcal{N}}}$ as well. Within the unified model for the two product spaces, we compute the tension field of ${\mathcal{N}}$ and extend to surfaces in ${{\mathbb{H}}^{2}\times{\mathbb{R}}}$ the equivalence between the CMC property and the harmonicity of ${\mathcal{N}.}$      

Branches of solutions to semilinear elliptic equations on mathbb{R}^N

For a large class of functions f, we consider the nonlinear elliptic eigenvalue problem We describe the behaviour of the branch of solutions emanating from an eigenvalue of odd multiplicity below the essential spectrum of the linearized problem. A sharper result is obtained in the case of the lowest eigenvalue. The discussion is based on the degree theory for proper Fredholm maps developed by P.M Fitzpatrick, J. Pejsachowicz and P.J. Rabier. Received November 13, 1996; in final form March 24, 1997     

Isometric Immersions into {\mathbb{S}^m \times \mathbb{R}} and {\mathbb{H}^m \times \mathbb{R}} with High Codimensions

In this paper, we obtain sufficient and necessary conditions for a simply connected Riemannian manifold (M ⁿ , g) to be isometrically immersed into ${\mathbb{S}^m \times \mathbb{R}}$ and ${\mathbb{H}^m \times \mathbb{R}}$ .     

Approximations for two variants of the Steiner tree problem in the Euclidean plane {\mathbb{R}^2}

Given n terminals in the Euclidean plane and a positive constant l, find a Steiner tree T interconnecting all terminals with the minimum total cost of Steiner points and a specific material used to construct all edges in T such that the Euclidean length of each edge in T is no more than l. In this paper, according to the cost b of each Steiner point and the different costs of some specific materials with the different lengths, we study two variants of the Steiner tree problem in the Euclidean plane as follows: (1) If a specific material to construct all edges in such a Steiner tree has its infinite length and the cost of per unit length of such a specific material used is c ₁, the objective is to minimize the total cost of the Steiner points and such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_1+ c_1 \cdot \sum_{e \in T} w(e)\}}$ , where T is a Steiner tree constructed, k ₁ is the number of Steiner points and w(e) is the length of part cut from such a specific material to construct edge e in T, and we call this version as the minimum-cost Steiner points and edges problem (MCSPE, for short). (2) If a specific material to construct all edges in such a Steiner tree has its finite length L (l ≤ L) and the cost of per piece of such a specific material used is c ₂, the objective is to minimize the total cost of the Steiner points and the pieces of such a specific material used to construct all edges in T, i.e., ${{\rm min} \{b \cdot k_2+ c_2 \cdot k_3\}}$ , where T is a Steiner tree constructed, k ₂ is the number of Steiner points in T and k ₃ is the number of pieces of such a specific material used, and we call this version as the minimum-cost Steiner points and pieces of specific material problem (MCSPPSM, for short). These two variants of the Steiner tree problem are NP-hard with some applications in VLSI design, WDM optical networks and wireless communications. In this paper, we first design an approximation algorithm with performance ratio 3 for the MCSPE problem, and then present two approximation algorithms with performance ratios 4 and 3.236 for the MCSPPSM problem, respectively.