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Dvoretzky's Theorem


Dvoretzky's theorem states that each centered convex body of sufficiently high dimension has an "almost spherical" k-dimensional central section.

Klartag and Moshe (2026) proved a polynomial bound in the approximation parameter. Let K subset= R^n be a convex body containing the origin in its interior, with 0<epsilon<1/2 and 2<=l<=n. If

 n>=(C/epsilon)^((l+1)/2)|lnepsilon|

for a universal constant C>0, then there are an l-dimensional linear subspace E and r>0 such that

 rB_E subset= K intersection E subset= (1+epsilon)rB_E,

where B_E is the unit ball in E. This resolves the conjecture that the required ambient dimension has polynomial dependence on 1/epsilon for fixed l.

Klartag and Moshe (2026) state that the choice of probability distribution used in the proof arose from a discussion between ChatGPT and Moshe. ChatGPT was also used to inspect and improve proofs.


See also

Convex Body, Subspace

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References

Klartag, B. and Moshe, S. "A Polynomial Bound in Dvoretzky's Theorem." 2 Oct 2026. https://arxiv.org/abs/2610.03204.

Referenced on Wolfram|Alpha

Dvoretzky's Theorem

Cite this as:

Weisstein, Eric W. "Dvoretzky's Theorem." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/DvoretzkysTheorem.html

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