Position of $L(X, Y)$ in $Lip_0(X, Y)$

TL;DR

This paper investigates the structure of Lipschitz and linear maps between metric and Banach spaces, establishing conditions for complemented subspaces, introducing vector-valued Lipschitz-free spaces, and characterizing duality and kernels.

Contribution

It proves that $L(X,Y)$ is complemented in $Lip_0(X,Y)$ when $Y$ is a dual space, introduces a new vector-valued Lipschitz-free space, and characterizes the kernel of a specific contraction map.

Findings

$L(X,Y)$ is complemented in $Lip_0(X,Y)$ for dual $Y$

The quotient $Lip_0(X,Y)/L(X,Y)$ is isometrically isomorphic to $L( ext{ker}(eta_X^Y),Y)$ when $Y$ is injective

Characterization of the kernel of $eta_{ eal}^{ eal}$ as the pre-dual of a quotient space

Abstract

We prove that $L(X,Y)$ is complemented in $Lip_0(X, Y)$ (via a norm-one projection) provided that $Y$ is a dual space. Next, we introduce a vector-valued Lipschitz-free space $F_Y(X)$, a linear contraction $\beta_X^Y: F_Y(X) \to Y$ and prove that the quotient space ${Lip_{0}(X, Y)}/{L(X, Y) }$ is isometrically isomorphic to $L(\ker(\beta_X^Y), Y)$ whenever $Y$ is injective. We also consider a $Y$-valued duality pairing between $Lip_0(X, Y)$ and $F_Y(X)$ and obtain a necessary and sufficient condition for a Lipschitz map to be linear. As an application, we describe $\ker(\beta_{\mathbb{R}}^{\mathbb{R}})$ as the pre-dual of the quotient space $L^{\infty}(\mathbb{R})/\tilde{\mathbb{R}}$ where $\tilde{\mathbb{R}}$ is the set of all constant maps on $\mathbb{R}$.