# Substitution in Expression of Symmetric Functions over Polynomial Ring

Hi everyone! So I'm working in the ring of symmetric functions over a polynomial ring, say $\mathbb{Q}[q]$, and I have an expression of the form

$$ q^2s_{2,1} + (q-1)s_{1,1,1}$$

I want to perform the substitution $q = q+1$ in this expression, but all of the usual methods (subs, substitute, etc.) give me an error. Does anyone know how to do this?

Thanks in advance!