Lipschitz free spaces isomorphic to their infinite sums and geometric applications
Fernando Albiac, José L. Ansorena, Marek Cúth, Michal Doucha
Abstract
We find general conditions under which Lipschitz-free spaces over metric spaces are isomorphic to their infinite direct $\ell _1$-sum and exhibit several applications. As examples of such applications we have that Lipschitz-free spaces over balls and spheres of the same finite dimensions are isomorphic, that the Lipschitz-free space over $\mathbb {Z}^d$ is isomorphic to its $\ell _1$-sum, or that the Lipschitz-free space over any snowflake of a doubling metric space is isomorphic to $\ell _1$. Moreover, following new ideas of Bruè et al. from [J. Funct. Anal. 280 (2021), pp. 108868, 21] we provide an elementary self-contained proof that Lipschitz-free spaces over doubling metric spaces are complemented in Lipschitz-free spaces over their superspaces and they have BAP. Everything, including the results about doubling metric spaces, is explored in the more comprehensive setting of $p$-Banach spaces, which allows us to appreciate the similarities and differences of the theory between the cases $p<1$ and $p=1$.