We recall the definition of Minimizing Movements, suggested by E. De Giorgi, and we consider some applications to evolution problems. With regards to ordinary differential equations, we prove in particular a generalization of maximal slope curves theory to arbitrary metric spaces. On the other hand we present a unifying framework in which some recent conjectures about partial differential equations can be treated and solved. At the end we consider some open problems.

We use the genus theory to prove the existence and multiplicity of solutions for the fractional $p$-Kirchhoff problem $$\left\{\begin{array}{c}{\displaystyle -{\left[M\left({\int }_Q{\displaystyle \frac{{|u\left(x\right)-u\left(y\right)|}^p}{{|x-y|}^{N+ps}}}\mathrm{d}x\mathrm{d}y\right)\right]}^{p-1}{(-\Delta )}_p^{s}u=\lambda h(x,u)\text{in}\Omega ,}\hfill \\ u=0\text{on}{ℝ}^N\setminus \Omega ,\hfill \end{array}\right.$$ where $\Omega$ is an open bounded smooth domain of ${ℝ}^N$, $p>1$, $N>ps$ with $s\in (0,1)$ fixed, $Q={ℝ}^{2N}\setminus (C\Omega \times C\Omega )$, $\lambda >0$ is a numerical parameter, $M$ and $h$ are continuous functions.

In this paper we study the nonlinear Dirichlet problem involving p(x)-Laplacian (hemivariational inequality) with nonsmooth potential. By using nonsmooth critical point theory for locally Lipschitz functionals due to Chang [6] and the properties of variational Sobolev spaces, we establish conditions which ensure the existence of solution for our problem.

We consider the following Kirchhoff type problem involving a critical nonlinearity: ⎧ $-[a+b({\int }_{\Omega }{\left|\nabla u\right|²dx)}^m{]\Delta u=f(x,u)+|u|}^{2*-2}u$ in Ω, ⎨ ⎩ u = 0 on ∂Ω, where $\Omega \subset {ℝ}^N$ (N ≥ 3) is a smooth bounded domain with smooth boundary ∂Ω, a > 0, b ≥ 0, and 0 < m < 2/(N-2). Under appropriate assumptions on f, we show the existence of a positive ground state solution via the variational method.

We study the following singular elliptic equation with critical exponent ⎧$-\Delta u=Q\left(x\right)u^{2*-1}+\lambda u^{-\gamma }$ in Ω, ⎨u > 0 in Ω, ⎩u = 0 on ∂Ω, where $\Omega \subset {ℝ}^N$ (N≥3) is a smooth bounded domain, and λ > 0, γ ∈ (0,1) are real parameters. Under appropriate assumptions on Q, by the constrained minimizer and perturbation methods, we obtain two positive solutions for all λ > 0 small enough.