文摘
Let \(R\) be a ring with center \(Z\). A map \(D\) of \(R\) (resp. \(T\) of \(R\)) is called a centrally-extended derivation (resp. a centrally-extended endomorphism) if for each \(x,y\in R, D(x+y)-D(x)-D(y)\in Z\) and \(D(xy)-D(x)y-xD(y)\in Z\) (resp. \(T(x+y)-T(x)-T(y)\in Z\) and \(T(xy)-T(x)T(y)\in Z\)). We discuss existence of such maps which are not derivations or endomorphisms, we study their effect on \(Z\), and we give some commutativity results. Keywords Derivations Epimorphisms Centrally-extended derivations Centrally-extended epimorphisms Commutativity theorems