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A functional equation with a symmetric binary operation

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Abstract

Let X be a nonempty set containing at least two elements and let \({\circ :X^2\to X}\) be a symmetric binary operation. Furthermore, let A, B, C be real parameters and let \({f,g:X\to\mathbb{R}_+}\) be unknown functions. We investigate the functional equation

$$f(x\circ y)[Ag(y)-Bg(x)]=(A+C)f(x)g(y)-(B+C)f(y)g(x)\quad {\rm for\,\,all}\,x,y \in X.$$

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Correspondence to Judita Dascăl.

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Dedicated to Professor Janusz Matkowski on the occasion of his seventieth birthday

This research has been supported by the Hungarian Scientific Research Fund (OTKA) Grant NK 81402.

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Daróczy, Z., Dascăl, J. A functional equation with a symmetric binary operation. Aequat. Math. 82, 291–297 (2011). https://doi.org/10.1007/s00010-011-0095-9

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  • DOI: https://doi.org/10.1007/s00010-011-0095-9

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