sequence of variables



Hi, 
 
Why do Maxima change sequence of variables ?


 e.g. (a + b)?  gives (b + a)?  

(a - b)?   gives (a - b)?   no exchange

(a +b) * (a+b)  givews : (b+ a)?

(a + b +c)?  gives (c + b + a)?

can i change this behavior ?


regards wally