摘要
We find on a monoid M the complex-valued solutions f,g:M→C such that f is central and g is continuous of the functional equation f(xσ(y))+f(τ(y)x)=2f(x)g(y),x,y∈M,whereσ:M→M is an involutive automorphism andτ:M→M is an involutive anti-automorphism.The solutions are described in terms of multiplicative functions,additive functions and characters of2-dimensional representations of M.
基金
Supported by the National Science Foundation of China(Grant Nos.12061059 and 61763041)。
