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arXiv · 2604.26704

Strictly nonexpansive, strictly monotone quasi graph-additive functions

Tibor Kiss
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Abstract

In this paper, we provide a negative answer to an open problem concerning the functional equation \[f(f(-x)+x)=f(-f(x))+f(x),\] namely by showing that the family of continuous solutions is too rich to admit a complete description. Instead, we characterize the solutions within a certain subfamily.

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Tibor Kiss. 2026-04-29. Strictly nonexpansive, strictly monotone quasi graph-additive functions. https://arxiv.org/abs/2604.26704

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