Weighted fractional Poincar\'e inequalities via isoperimetric inequalities

Our main result is a weighted fractional Poincar\'e-Sobolev inequality improving the celebrated estimate by Bourgain-Brezis-Mironescu. This also yields an improvement of the classical Meyers-Ziemer theorem in several ways. The proof is based on a fractional isoperimetric inequality and is new even in the non-weighted setting. We also extend the celebrated Poincar\'e-Sobolev estimate with $A_p$ weights of Fabes-Kenig-Serapioni by means of a fractional type result in the spirit of Bourgain-Brezis-Mironescu. Examples are given to show that the corresponding $L^p$-versions of weighted Poincar\'e inequalities do not hold for $p>1$.