A new characterization of convexity of a planar domain is obtained. Its derivation involves two classical facts: the Varadhan formula expressing the distance function with respect to the boundary of a domain in terms of real-valued solutions to the modified Helmholtz equation and the convexity of a planar domain where the distance function is superharmonic.
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References
R. B. Burckel, “Three secrets about harmonic functions”, Am. Math. Monthly 104, 52–56 (1980).
D. H. Armitage and ¨U. Kuran, “The convexity of a domain and the superharmonicity of the signed distance function,” Proc. Am. Math. Soc. 93, 598–600 (1985).
R. J. Duffin, “Yukawan potential theory,” J. Math. Anal. Appl. 35, 105–130 (1971).
E. Hopf, “Elementare Bemerkungen ¨uber die L¨osungen partieller Differentialgleichungen zweiter Ordnung vom elliptischen Typus,” Sitzungsber. Preuss. Akad. Wiss., Phys.-Math. Kl. 19, 147–152 (1927).
D. E. Apushkinskaya and A. I. Nazarov, “The normal derivative lemma and surrounding issues,” Russ. Math. Surv. 77, No. 2, 189–249 (2022).
M. Abramowitz and I. A. Stegun (Eds.), Handbook of Mathematical Functions, US National Bureau of Standards, Washington, DC (1964).
S. R. S. Varadhan, “On the behavior of the fundamental solution of the heat equation with variable coefficients,” Comm. Pure Appl. Math. 20, 431–455 (1967).
F. A. Valentine, Convex Sets, McGraw-Hill, New York (1964).
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To N. N. Uraltseva with admiration
Translated from Problemy Matematicheskogo Analiza 127, 2024, pp. 117-120.
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Kuznetsov, N. The Convexity of a Planar Domain Via Properties of Solutions to the Modified Helmholtz Equation. J Math Sci 281, 607–611 (2024). https://doi.org/10.1007/s10958-024-07137-6
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DOI: https://doi.org/10.1007/s10958-024-07137-6