Limitations to fréchet's metric embedding method

Fréchet's classical isometric embedding argument has evolved to become a major tool in the study of metric spaces. An important example of a Fréchet embedding is Bourgain's embedding [4]. The authors have recently shown [2] that for every ε > 0, any n-point metric space contains a subset of size at least n^1-ε which embeds into ℓ₂ with distortion O(log(2/ε)/ε). The embedding used in [2] is non-Fréchet, and the purpose of this note is to show that this is not coincidental. Specifically, for every ε > 0, we construct arbitrarily large n-point metric spaces, such that the distortion of any Fréchet embedding into ℓ_p on subsets of size at least n ^1/2+ε is Ω((log n)^1/P).