Abstract
Let R denote the set of reals, J a real interval and X a real linear space. We determine the functions g : X →J, M : J → R and H : J 2 → R satisfying the equationg(x+M(g(x))y)=H(g(x),g(y)),under the assumptions that g is continuous on rays, M is continuous, and H is symmetric. As a consequence we obtain characterizations of some groups and semigroups.
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Brzdęk, J. A generalization of addition formulae. Acta Mathematica Hungarica 101, 281–291 (2003). https://doi.org/10.1023/B:AMHU.0000004940.94722.b4
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DOI: https://doi.org/10.1023/B:AMHU.0000004940.94722.b4