Regularity properties of functional equations and inequalities.
Relative rearrangement and interpolation inequalities.
We prove here that the Poincaré-Sobolev pointwise inequalities for the relative rearrangement can be considered as the root of a great number of inequalities in various sets not necessarily vector spaces. In particular, new interpolation inequalities can be derived.
Remarks on stability of functional equations.
Remarks on the stability of functional equations.