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On the necessity of gaps

Hiroshi Matano, Paul Rabinowitz (2006)

Journal of the European Mathematical Society

Recent papers have studied the existence of phase transition solutions for Allen–Cahn type equations. These solutions are either single or multi-transition spatial heteroclinics or homoclinics between simpler equilibrium states. A sufficient condition for the construction of the multitransition solutions is that there are gaps in the ordered set of single transition solutions. In this paper we explore the necessity of these gap conditions.

On the Newton-Kantorovich theorem and nonlinear finite element methods

Ioannis K. Argyros (2009)

Applicationes Mathematicae

Using a weaker version of the Newton-Kantorovich theorem, we provide a discretization result to find finite element solutions of elliptic boundary value problems. Our hypotheses are weaker and under the same computational cost lead to finer estimates on the distances involved and a more precise information on the location of the solution than before.

On the nonlinear Neumann problem at resonance with critical Sobolev nonlinearity

J. Chabrowski, Shusen Yan (2002)

Colloquium Mathematicae

We consider the Neumann problem for the equation - Δ u - λ u = Q ( x ) | u | 2 * - 2 u , u ∈ H¹(Ω), where Q is a positive and continuous coefficient on Ω̅ and λ is a parameter between two consecutive eigenvalues λ k - 1 and λ k . Applying a min-max principle based on topological linking we prove the existence of a solution.

On the number of positive solutions of singularly perturbed 1D nonlinear Schrödinger equations

Patricio Felmer, Salomé Martínez, Kazunaga Tanaka (2006)

Journal of the European Mathematical Society

We study singularly perturbed 1D nonlinear Schrödinger equations (1.1). When V ( x ) has multiple critical points, (1.1) has a wide variety of positive solutions for small ε and the number of positive solutions increases to as ε 0 . We give an estimate of the number of positive solutions whose growth order depends on the number of local maxima of V ( x ) . Envelope functions or equivalently adiabatic profiles of high frequency solutions play an important role in the proof.

On the semilocal convergence of a two-step Newton-like projection method for ill-posed equations

Ioannis K. Argyros, Santhosh George (2013)

Applicationes Mathematicae

We present new semilocal convergence conditions for a two-step Newton-like projection method of Lavrentiev regularization for solving ill-posed equations in a Hilbert space setting. The new convergence conditions are weaker than in earlier studies. Examples are presented to show that older convergence conditions are not satisfied but the new conditions are satisfied.

On the solution and applications of generalized equations using Newton's method

Ioannis K. Argyros (2004)

Applicationes Mathematicae

We provide local and semilocal convergence results for Newton's method when used to solve generalized equations. Using Lipschitz as well as center-Lipschitz conditions on the operators involved instead of just Lipschitz conditions we show that our Newton-Kantorovich hypotheses are weaker than earlier sufficient conditions for the convergence of Newton's method. In the semilocal case we provide finer error bounds and a better information on the location of the solution. In the local case we can provide...

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