composition of functions.



Dear all,

I want to compute compositions of functions. I define

a(x, y, z):= [-x, x+y, z];
ee(x,y,z):=p^(x)*q^(y)*r^(z);
b(x, y, z):=[x+y, -y, 2*y+z];
c(x, y, z):=[x, y+z, -z];

s2:ee(a(b(a(b(c(b(a(b(x, y, z)))))))));

Then it has errors "Too few" arguments supplied to a(x,y,z); found:
[[y+x,-y,z+2*y]]
 -- an error.

How can I define the functions correctly? Thank you very much.

Best wishes,
Jianrong.