A derivation is a function on an algebra which generalizes certain features of the derivative operator. Specifically, given an algebra A over a ring or field K, an K-derivation is an K-linear map D from A to itself that satisfies Leibniz's law: D(ab)=(Da)b+a(Db). More generally, an K-linear map D of A into an A-module M, satisfying the Leibniz law is also called a derivation. The collection of all K-derivation of A to itself is denoted by Der(A). The collection of K-derivations of A into an A-module M is denoted by Der(A, M). Derivations occur in many different contexts in diverse areas of...