Gapplet

You input a polynomial f Z[x,y]. We then view it as the recipee for a binary operation on Z, mapping (a,b) Z×Z to f(a,b) Z, and we analyse whether the operation is commutative.

Input a polynomial f in x, y with integral coefficients, 
e.g., x*y+x+y.
Test whether the corresponding binary map is commutative
 
We compute f(y,x) and compare it to f(x,y). By arguments as in Lagrange interpolation, equality of these two polynomials in x, y is equivalent to commutativity.