Dimension reduction techniques for $\ell_p$, $1 \le p \le 2$, with applications

Abstract

For Euclidean space ($\ell_2$), there exists the powerful dimension reduction transform of Johnson and Lindenstrauss, with a host of known applications. Here, we consider the problem of dimension reduction for all $\ell_p$ spaces $1 \le p \le 2$. Although strong lower bounds are known for dimension reduction in $\ell_1$, Ostrovsky and Rabani successfully circumvented these by presenting an $\ell_1$ embedding that maintains fidelity in only a bounded distance range, with applications to clustering and nearest neighbor search. However, their embedding techniques are specific to $\ell_1$ and do not naturally extend to other norms. In this paper, we apply a range of advanced techniques and produce bounded range dimension reduction embeddings for all of $1 \le p \le 2$, thereby demonstrating that the approach initiated by Ostrovsky and Rabani for $\ell_1$ can be extended to a much more general framework. We also obtain improved bounds in terms of the intrinsic dimensionality. As a result we achieve improved bounds for proximity problems including snowflake embeddings and clustering.