Dear all, I applied the patch that I was talking about. The points are (1) Added a simplification rules for powers that turns (x^a)^b into x^(a*b) in the case that x is positive and a is real. (2) Improved expansion of powers. In the case that a power is raised to an integer power, we should not simply be doing (x^a)^n -> expair(x, a*n) because this is wrong if x=y^2, a=1/2 and n=2. Then we get ((y^2)^(1/2))^2 -> expair(y^2, 1), which should be expair(y, 2). Happy releasing, Chris