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The Randomized k-Server Conjecture

open

· online algorithms · ~1 min read · difficulty 4/5

online-algorithms

The problem

Randomized k-server conjecture: on every metric space there is a randomised online \(k\)-server algorithm whose competitive ratio is polylogarithmic in \(k\) alone — \(O(\mathrm{polylog}\, k)\), with no dependence on the number of points of the space.

History & significance

Randomisation beats every deterministic lower bound for paging and for k-server on special metrics, so the natural question is how far it goes in general. Bansal et al. (2015) gave the first polylogarithmic-in-\(n\) algorithm via HST embeddings; Bubeck et al. (2018) reached \(O(\log^2 k \log n\) via multiscale entropic regularisation, and Lee (2018) proposed dynamic embeddings toward a \(k\)-only bound. The remaining gap — removing the dependence on the number of points \(n\) — is the conjecture.

Still open.

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