#	replace(a,b,c);

replace(a_ and b_,y_,x_):=replace(a,y,x) and replace(b,y,x);
replace(a_*b_,y_,x_):=replace(a,y,x)*replace(b,y,x);
replace(a_+b_,y_,x_):=replace(a,y,x)+replace(b,y,x);
replace(ints(y_,t_,a_,b_),p_,c_):=ints(replace(y,p,replace(c,x,t)),t,a,b);
replace(int(y(tt_),t_,a_,b_),p_,c_):=int(replace(c,x,inverse(tt,t)),t,a,b);