arXiv subjects
Publications and source records attributed to D. D. Repovš.
We show that for any set of primes $\mathcal{P}$ there exists a space $M_{\mathcal{P}}$ which is a homology and cohomology 3-manifold with coefficients in $\mathbb{Z}_{p}$ for $p\in \mathcal{ P}$ and is not a homology or cohomology 3-manifold with coefficients in $\mathbb{Z}_q$ for $q\not\in \mathcal{ P}$. Moreover, $M_{\mathcal{P}}$ is neither a homology nor cohomology 3-manifold with coefficients in $\mathbb{Z}$ or $\mathbb{Q}$.
We consider a parametric semilinear Robin problem driven by the Laplacian plus an indefinite potential. The reaction term involves competing nonlinearities. More precisely, it is the sum of a parametric sublinear (concave) term and a superlinear (convex) term. The superlinearity is not expressed via the Ambrosetti-Rabinowitz condition. Instead, a more general hypothesis is used. We prove a bifurcation-type theorem describing the set of positive solutions as the parameter $λ> 0$ varies. We also show the existence of a minimal positive solution $\tilde{u}_λ$ and determine the monotonicity and continuity properties of the map $λ\mapsto \tilde{u}_λ$.
We study perturbations of the eigenvalue problem for the negative Laplacian plus an indefinite and unbounded potential and Robin boundary condition. First we consider the case of a sublinear perturbation and then of a superlinear perturbation. For the first case we show that for $λ<\widehatλ_{1}$ ($\widehatλ_{1}$ being the principal eigenvalue) there is one positive solution which is unique under additional conditions on the perturbation term. For $λ\geq\widehatλ_{1}$ there are no positive solutions. In the superlinear case, for $λ<\widehatλ_{1}$ we have at least two positive solutions and for $λ\geq\widehatλ_{1}$ there are no positive solutions. For both cases we establish the existence of a minimal positive solution $\bar{u}_λ$ and we investigate the properties of the map $λ\mapsto\bar{u}_λ$.
We study the existence and multiplicity results for the following nonlocal $p(x)$-Kirchhoff problem: \begin{equation} \label{10} \begin{cases} -\left(a-b\int_Ω\frac{1}{p(x)}| \nabla u| ^{p(x)}dx\right)div(|\nabla u| ^{p(x)-2}\nabla u)=λ|u| ^{p(x)-2}u+g(x,u) \mbox{ in } Ω, \\ u=0,\mbox{ on } \partialΩ, \end{cases} \end{equation} where $a\geq b > 0$ are constants, $Ω\subset \mathbb{R}^N$ is a bounded smooth domain, $p\in C(\overlineΩ)$ with $N>p(x)>1$, $λ$ is a real parameter and $g$ is a continuous function. The analysis developed in this paper proposes an approach based on the idea of considering a new nonlocal term which presents interesting difficulties.