Norm and essential norm of differences of differentiation composition operators between Bloch spaces have been estimated in this paper. As a result, we find characterizations for boundedness and compactness of these operators.

In the Theory of the Seiberg-Witten Equations, the configuration space is Cα = Aα × Γ (S + α ), where Aα is a space of u1-connections and Γ (S + α ) is the space of sections of the complex spinor bundle over X. Since the SWequation fits in a variational approach, invariant by the action of the Gauge Group Gα = Map(X,U1), which satisfies the Palais-Smale Condition, our aim is to obtain existence...

Let (S3, c) be the standard 3-sphere, i.e., the 3-sphere equipped with the standard metric. Let K be a C2 positive function on S3. The Kazdan-Warner problem [l] is the problem of finding suitable conditions on K such that K is the scalar curvature for a metric g on S3 conformally equivalent to c. The metric g then reads g=u4c and u is a positive function on S3 satisfying the partial differentia...

We use variational methods to study the existence and multiplicity of solutions for the following quasi-linear partial differential equation: ( −4pu = λ|u|r−2u+ μ |u| q−2 |x|s u in Ω, u|∂Ω = 0, where λ and μ are two positive parameters and Ω is a smooth bounded domain in Rn containing 0 in its interior. The variational approach requires that 1 < p < n, p ≤ q ≤ p∗(s) ≡ n−s n−pp and p ≤ r ≤ p ∗ ≡...

In this paper, we establish a variant of Ekeland’s variational principle. This result suggest to introduce a generalization of the famous PalaisSmale condition. An example is provided showing how it is used to give the existence of minimizer for functions for which the Palais-Smale condition and the one introduced by Cerami are not satisfied.

Since the development of the calculus of variations there has been interest in finding critical points of functionals. This was intensified by the fact that for many equations arising in practice the solutions are critical points of functionals. If a functional G is semibounded, one can find a Palais-Smale (PS) sequence G(uk) → a, G(uk) → 0. These sequences produce critical points if they have ...

Fixing a complete Riemannian metric g on Rn, we show that a local diffeomorphism f : Rn → Rn is bijective if the height function f · v (standard inner product) satisfies the Palais-Smale condition relative to g for each for each nonzero v ∈ Rn. Our method substantially improves a global inverse function theorem of Hadamard. In the context of polynomial maps, we obtain new criteria for invertibi...

In this paper, countable compactness and the Lindel¨of propertyare defined for L-fuzzy sets, where L is a complete de Morgan algebra. Theydon’t rely on the structure of the basis lattice L and no distributivity is requiredin L. A fuzzy compact L-set is countably compact and has the Lindel¨ofproperty. An L-set having the Lindel¨of property is countably compact if andonly if it is fuzzy compact. ...