%0 Journal Article
%T On cosine families close to scalar cosine families
%A Wojciech Chojnacki
%J Mathematics
%D 2014
%I arXiv
%R 10.1017/S1446788715000038
%X We prove that if two normed-algebra-valued cosine families indexed by a single Abelian group, of which one is bounded and comprised solely of scalar elements of the underlying algebra, differ in norm by less than $1$ uniformly in the parametrising index, then these families coincide.
%U http://arxiv.org/abs/1411.0854v5