Let f(x) be a nonzero, bounded, real function on an Abelian group G, g1,...,gk are given elements of G and λ1,...,λk are real numbers. Prove that if i=1∑kλif(gix)≥0 holds for all x∈G, then i=1∑kλi≥0.
A. Mate functionabstract algebragroup theoryreal analysisreal analysis unsolved