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math.FA2015
Sine and cosine equations on commutative hypergroups
Żywilla Fechner, László Székelyhidi
In this paper we describe the solutions of the functional equations expressing the addition theorems for sine and cosine on commutative hypergroups.
math.FA2014★ 4 cited
A Generalization of Gajda's Equation on Commutative Topological Groups
Ż. Fechner, L. Székelyhidi
In the present paper we deal with the following generalization of the sine-cosine equation \begin{equation*} \int f_1(x+y-t)+f_2(x-y+t) dμ(t)=g(x)h(y) \end{equation*} for complex v…