Weighted Gagliardo-Nirenberg inequalities via Optimal Transport Theory and Applications
Zoltán M. Balogh, Sebastiano Don, Alexandru Kristály
TL;DR
The paper develops three-weight Gagliardo–Nirenberg inequalities on open convex cones via an optimal mass transport framework, establishing a central joint concavity condition $(C)$ that ties together three homogeneous weights. It delivers sharp constants and extremal characterizations in the equal-weight case, and proves a rigidity result showing that sharpness with attainment forces the weights to coincide up to a scalar and the transport map to be affine. The authors derive a wide spectrum of sharp weighted inequalities as applications, including sharp weighted Sobolev and GN inequalities, a limit $p$-log-Sobolev inequality as $\gamma\to1$, and sharp weighted Faber–Krahn and isoperimetric inequalities; they also discuss the dual formulation for $\gamma>1$ and the open problem of full equality characterization in that regime. Overall, the work provides a unified transport-based mechanism to obtain and analyze sharp weighted functional inequalities in conic domains with explicit constants and rigidity results.
Abstract
We prove Gagliardo-Nirenberg inequalities with three weights -- verifying a joint concavity condition -- on open convex cones of $\mathbb R^n$. If the weights are equal to each other the inequalities become sharp and we compute explicitly the sharp constants. For a certain range of parameters we can characterize the class of extremal functions; in this case, we also show that the sharpness in the main three-weighted Gagliardo-Nirenberg inequality implies that the weights must be equal up to some constant multiplicative factors. Our approach uses optimal mass transport theory and a careful analysis of the joint concavity condition of the weights. As applications we establish sharp weighted $p$-log-Sobolev, Faber-Krahn and isoperimetric inequalities with explicit sharp constants.
