I'm working with polynomials of 5 variables $a,b,p,q,r$ which have a condition $a+b=p+q+r$. I'd like to minimize the number of variables in the answer. However, FullSimplify can't handle even simple example:
pol=p+q+r-b; FullSimplify[pol, Assumptions -> a + b == p + q + r]
-b + p + q + r
Is there a way to do it?