Coincidence theorems for subadditive and superadditive functions

We give some necessary and sufficient conditions in order that a quasi-subadditive function should coincide with a quasi-superadditive one. Thus, we can easily prove a straightforward extension of a theorem of Marek Kuczma on the linearity of a subadditive function majorized by a differentiable one.

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Author(s)

Burai, Pal, Szaz, Arpad