Fractional boundary Hardy inequality for the critical cases

We establish generalised fractional boundary Hardy-type inequality, in the spirit of Caffarelli-Kohn-Nirenberg inequality for different values of $s$ and $p$ on various domains in ${\mathbb{R}}^d,d\ge 1$. In particular, for Lipschitz bounded domains any values of $s$ and $p$ are admissible, settling all the cases in subcritical, supercritical and critical regime. In this paper we have solved the open problems posed by Dyda for the critical case $sp=1$. Moreover we have proved the embeddings of $W_0^{s,p}(\mathrm{\Omega })$ in subcritical, critical and supercritical uniformly without using Dyda’s decomposition. Additionally, we extend our results to include a weighted fractional boundary Hardy-type inequality for the critical case.