Derivation of an algebra
= Derivation of an algebra
For an $A$-algebra $B$ and a $B$-module $M$, an $A$-linear derivation is an additive map $D:B\to M$ satisfying $D(a)=0$ for $a\in A$ and the Leibniz rule $D(bb')=bD(b')+b'D(b)$.
= Derivation of an algebra
For an $A$-algebra $B$ and a $B$-module $M$, an $A$-linear derivation is an additive map $D:B\to M$ satisfying $D(a)=0$ for $a\in A$ and the Leibniz rule $D(bb')=bD(b')+b'D(b)$.