D’Alembert’s functional equation on topological groups

@article{Davison2008DAlembertsFE,
  title={D’Alembert’s functional equation on topological groups},
  author={Thomas M. Davison},
  journal={Aequationes mathematicae},
  year={2008},
  volume={76},
  pages={33-53}
}
Summary.D’Alembert’s equation f(xy) + f(xy−1) = 2f(x)f(y) is solved for all compact groups: all solutions come from continuous homomorphisms from the group to $$SU_2 (\mathbb{C})$$. We introduce the notion of a basic d’Alembert function: a continuous solution for which f(xy) = f(y) for all y implies that x = e. It is shown that every d’Alembert function factors through a basic d’Alembert function. We show that the only compact groups that support a basic d’Alembert function are topologically… CONTINUE READING