A Kannappan-sine addition law on semigroups

Ahmed Jafar, Omar Ajebbar, Elhoucien Elqorachi

Let $S$ be a semigroup and $z_0$ a fixed element in $S.$ We determine the complex-valued solutions of the following Kannappan-sine addition law $f(xyz_{0})=f(x)g(y)+f(y)g(x),x,y\…