Let $G=SL_n$ for $n=2$ or $n=3$. We will consider two different bases for the space of $G$ invariants in a tensor product of fundamental $G$ representations. The first is constructed via a set of labeled trivalent graphs called webs. The second is indexed by the irreducible components of certain Springer fibres. From a web we can construct a variety with natural projection to a Springer fibre. Using this projection we can than deduce that at $n=3$ these bases are not equal and that the change of basis is upper unitriangular.

This is joint work with Joel Kamnitzer and Greg Kuperberg.