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Krzyż Conjecture


The Krzyż conjecture asserts that every analytic function f(z)=sum_(k=0)^(infty)a_kz^k from the unit disk to the punctured unit disk satisfies |a_n|<=2/e for every positive integer n. The proposed extremal functions are

 f(z)=zetaexp(-(1-(epsilonz)^n)/(1+(epsilonz)^n)),

where |zeta|=|epsilon|=1.

Wikström (2026) proved the conjecture, including the equality characterization, for n=6. The proof combines an analytic reduction with rigorous computer-assisted exclusion of extremals with fewer than six atoms in their integral representation. The general conjecture remains open.

Wikström (2026) reports using Claude for numerical exploration and verification-code development, with a separate GPT-6 Astra code review. The author checked the arguments and code.

Xie (2026) proved the seventh-coefficient case, including the same equality characterization with n=7. The proof combines an analytic reduction with finite rational inequalities excluding extremizers supported on at most six atoms. Wikström (2026, p. 2) independently proved the same case by validated elimination of masses in the integral representation followed by computer-assisted exclusions.

MacDonald (2026, pp. 2-3) proved Peretz's conjecture that any f maximizing |a_n| in the class of bounded zero-free analytic functions above has |f(0)|<=1/e, for every positive integer n.


See also

Analytic Function, Taylor Series, Unit Disk

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References

MacDonald, S. F. "A Convolution Inequality and the Krzyż Conjecture." 5 Nov 2026. https://arxiv.org/abs/2611.05363v2.Wikström, F. "A Computer-Assisted Proof of Krzyż's Conjecture for the Sixth Coefficient." 4 Nov 2026. https://arxiv.org/abs/2610.15206v2.Xie, X. "Krzyż's Conjecture for the Seventh Coefficient." 30 Oct 2026. https://arxiv.org/abs/2611.00397v1.

Cite this as:

Weisstein, Eric W. "Krzyż Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/KrzyzConjecture.html

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