Let X be a finite-dimensional normed space. We prove that if the Hamming cube {-1,1}ⁿ embeds into X with bi-Lipschitz distortion at most D ≥ 1, then dim(X) ≳ sup_{p ∈ [1,2]} n^p/(D^p 𝖳_p(X)^p), where 𝖳_p(X) is the Rademacher type p constant of X. This estimate yields a mutual refinement of distortion lower bounds which follow from works of Oleszkiewicz (1996) and Ivanisvili, van Handel and Volberg (2020). The proof relies on a combination of semigroup techniques on the biased hypercube with the Borsuk-Ulam theorem from algebraic topology.
@InProceedings{eskenazis:LIPIcs.SoCG.2024.55, author = {Eskenazis, Alexandros}, title = {{Dimensionality of Hamming Metrics and Rademacher Type}}, booktitle = {40th International Symposium on Computational Geometry (SoCG 2024)}, pages = {55:1--55:13}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-316-4}, ISSN = {1868-8969}, year = {2024}, volume = {293}, editor = {Mulzer, Wolfgang and Phillips, Jeff M.}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2024.55}, URN = {urn:nbn:de:0030-drops-200004}, doi = {10.4230/LIPIcs.SoCG.2024.55}, annote = {Keywords: Hamming cube, Rademacher type, metric embeddings, Borsuk-Ulam theorem} }
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