Homework Statement
Let ##R## be a commutative ring,. Show that ##R[x,y]## is isomorphic to ##R[y,x]##.
Homework EquationsThe Attempt at a Solution
Let ##f : R[x,y] \to R[y,x]## be defined by ##\sum_{i,j=1}^{n,m} a_{ij} x^i y^j \mapsto \sum_{i,j=1}^{n,m} a_{ij} y^i x^j##. Verifying that ##f##...