Multibump solutions for discrete periodic nonlinear Schrödinger equations

In this paper, we study the existence of multibump solutions for discrete nonlinear Schrödinger equations with periodic potentials. We first reduce the existence of multibump homoclinic solutions to the existence of an isolated homoclinic solution with a nontrivial critical group. Then, we study the existence of homoclinics with nontrivial critical groups for both superlinear and asymptotically linear discrete periodic nonlinear Schrödinger equations, and we provide simple sufficient conditions for the existence of homoclinics with nontrivial critical groups in the positive definite case. As an application, we get, without any symmetry assumptions, infinitely many geometrically distinct homoclinic solutions with exponential decay at infinity.     

Homoclinic orbits for second order nonlinear <Emphasis Type="Italic">p</Emphasis>-Laplacian difference equations

The paper proves the existence of nontrivial homoclinic orbits for second order nonlinear p-Laplacian difference equations without assumptions on periodicity using the critical point theory. Moreover, if the nonlinearity is an odd function, the existence of an unbounded sequence of nontrivial homoclinic orbits is proved.     

Homoclinic orbits for nonlinear difference equations containing both advance and retardation

In this paper we discuss how to use the critical point theory to study the existence of a nontrivial homoclinic orbit for nonlinear difference equations containing both advance and retardation without any periodic assumptions. Moreover, if the nonlinearity is an odd function, the existence of an unbounded sequence of homoclinic orbits is obtained.     

p拉普拉斯Dirichlet问题的非平凡解

研究一类特殊的p拉普拉斯Dirichlet问题.当非线性项在正无穷远处是超线性而在负无穷远处是渐近线性情形,使用极小极大方法建立非平凡解的存在性结果.     

Homoclinic orbits and subharmonics for nonlinear second order difference equations

We show the existence of a nontrivial homoclinic orbit and subharmonic solutions for a class of second order difference equations by applying the “Mountain Pass” theorem relying on Ekeland’s variational principle and the diagonal method, and the homoclinic orbit as the limit of the subharmonics. A completely new way is provided for dealing with the existence of solutions for difference equations.     

Multiplicity results for elliptic fractional equations with subcritical term

In the present paper, by using variational methods, we study the existence of multiple nontrivial weak solutions for parametric nonlocal equations, driven by the fractional Laplace operator \({(-\Delta)^{s}}\) , in which the nonlinear term has a sublinear growth at infinity. More precisely, a critical point result for differentiable functionals is exploited, in order to prove the existence of an open interval of positive eigenvalues for which the treated problem admits at least two nontrivial weak solutions in a suitable fractional Sobolev space.     

Global bifurcation of homoclinic trajectories of discrete dynamical systems

We prove the existence of an unbounded connected branch of nontrivial homoclinic trajectories of a family of discrete nonautonomous asymptotically hyperbolic systems parametrized by a circle under assumptions involving topological properties of the asymptotic stable bundles.     

Multi-bump orbits homoclinic to resonance bands

We establish the existence of several classes of multi-bump orbits homoclinic to resonance bands for completely-integrable Hamiltonian systems subject to small-amplitude Hamiltonian or dissipative perturbations. Each bump is a fast excursion away from the resonance band, and the bumps are interspersed with slow segments near the resonance band. The homoclinic orbits, which include multi-bump \v{S}ilnikov orbits, connect equilibria and periodic orbits in the resonance band. The main tools we use in the existence proofs are the exchange lemma with exponentially small error and the existence theory of orbits homoclinic to resonance bands which make only one fast excursion away from the resonance bands.

     

Nontrivial solutions for Neumann problems with an indefinite linear part

In this paper, we consider a semilinear Neumann problem with an indefinite linear part and a Carathéodory nonlinearity which is superlinear near infinity and near zero, but does not satisfy the Ambrosetti-Rabinowitz condition. Using an abstract existence theorem for C¹-functions having a local linking at the origin, we establish the existence of at least one nontrivial smooth solution.     

Periodic solutions for an asymptotically linear wave equation with resonance

In this paper, we study the existence and multiplicity of nontrivial periodic solutions for an asymptotically linear wave equation with resonance, both at infinity and at zero. The main features are using Morse theory for the strongly indefinite functional and the precise computation of critical groups under conditions which are more general.     

HOMOCLINIC ORBITS FOR A CLASS OF HAMILTONIAN SYSTEMS WITH POTENTIALS CHANGING SIGN

In this paper, we prove the existence of nontrivial homoclinic orbits for a class of Hamiltonian systems with potential changing sign. We use Mountain Pass Lemma.     

Existence of bound states for the coupled Schrödinger–KdV system with cubic nonlinearity

We prove in this Note the existence of an infinite family of smooth positive bound states for the coupled Schrödinger–Korteweg–de Vries system, which decays exponentially at infinity.     

Existence of solutions for a system of diffusion equations with spectrum point zero

In this paper, we consider the existence and multiplicity of homoclinic type solutions to a system of diffusion equations with spectrum point zero. By using some recent critical point theorems for strongly indefinite problems, we obtain at least one nontrivial solution and also infinitely many solutions.     

Homoclinic solutions for a class of asymptotically quadratic Hamiltonian systems

In this paper we are devoted to considering the existence of homoclinic solutions for some second order non-autonomous Hamiltonian systems with the asymptotically quadratic potential at infinity. The proof is based on a variant version of the Mountain Pass Theorem. Recent results in the literature are generalized and significantly improved.     

Computations of critical groups and applications to some differential equations at resonance

In this paper, we first consider the computations of the critical groups of a functional with generalized Ahmad–Lazer–Paul type conditions both at zero and infinity. Then the abstract results are applied to investigate some new cases of the existence of nontrivial solutions of the second order Hamiltonian systems and elliptic boundary value problems, which may be resonant both at zero and infinity.     

A Multiplicity Result for Some Integro-differential Biharmonic Equation in R4

In this paper, we prove the existence of at least three nontrivial solutions for some biharmonic elliptic equation involving an integral term. The nonlinear term exhibits an exponential growth at infinity. Our method consists of a combination between variational tools and iterative technique.     

Existence of nontrivial solutions for Kirchhoff-type problems with jumping nonlinearities

In this study, the Fučik spectrum is used to investigate Kirchhoff-type problems with jumping nonlinearities at infinity, and a new result on the existence of nontrivial solutions is obtained.     

Existence of nontrivial homoclinic orbits for fourth-order difference equations

We obtain a sufficient condition for the existence of nontrivial homoclinic orbits for fourth-order difference equations by using Mountain Pass Theorem, a weak convergence argument and a discrete version of Lieb’s lemma.     

具有小受迫项的哈密顿系统的同宿轨道

By Brezis-Nirenberg type Mountain Pass Theorem, the research has focused on the existence of nontrivial homoclinic orbits for a class of second order Hamiltonian systems with non-Ambrosetti-Rabinowitz type superquadratic potentials and small forced terms.     

Solutions to a gradient system with resonance at both zero and infinity

In this paper, we study the existence and multiplicity of nontrivial solutions for a gradient system with resonance at both zero and infinity via Morse theory.