(VAR x y) (RULES D(t()) -> 1 D(constant()) -> 0 D(+(x,y)) -> +(D(x),D(y)) D(*(x,y)) -> +(*(y,D(x)) , *(x,D(y))) D(-(x,y)) -> -(D(x),D(y)) D(minus(x)) -> minus(D(x)) D(div(x,y)) -> -(div(D(x),y) , div(*(x,D(y)),pow(y,2))) D(ln(x)) -> div(D(x),x) D(pow(x,y)) -> +(*(*(y,pow(x,-(y,1))),D(x)) , *(*(pow(x,y),ln(x)),D(y))) ) (COMMENT Example 11 in \cite{D33})