We point out a connection between reflection principles and generic large cardinals. One principle of pure reflection is introduced that is as strong as generic supercompactness of ω2 by σ-closed forcing. This new concept implies CH and extends the reflection principles for stationary sets in a canonical way.

An improvement of the author’s result, proved in 1961, concerning necessary and sufficient conditions for the compactness of embedding operators is given. A discussion of the necessity of the compatibility of the norms of the Banach spaces X2 and X3, where X2 ⊂ X3, is given. The injectivity of the embedding operator J : X2 → X3 implies this compatibility.

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 prove that for a uniformly convex Lagrangian system L on a compact manifold M , almost all energy levels contain a periodic orbit. We also prove that below Mañé’s critical value of the lift of the Lagrangian to the universal cover, cu(L), almost all energy levels have conjugate points. We prove that if the energy level [E = k] is of contact type and M 6= T then the free time action functiona...

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 ...

This paper considers bifurcation at the principal eigenvalue of a class of gradient operators which possess the Palais-Smale condition. The existence of the bifurcation branch and the asymptotic nature of the bifurcation is verified by using the compactness in the Palais Smale condition and the order of the nonlinearity in the operator. The main result is applied to estimate the asyptotic behav...

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...

This paper studies the stability properties of the concepts of local compactness introduced by the authors in 1998. We show that all of these concepts are stable for contractive, expansive images and for products. 1. Introduction. Having introduced notions of local compactness, basis local compactness and related measures, and having studied the basic relationship among these concepts in [3], i...