Evaluating Spin Network States

Hello. I'm finishing an undergraduate research project on lattice gauge theory, and I have a question about spin network states: in short, is there any efficient method for evaluating them when some random group elements g_1, g_2, g_3... are assigned to the edges, beyond doing the whole contraction ``by hand``? My gauge groups are SU(2) and SU(3).

To avoid confusion, here's my understanding of spin network states:
1) Take some lattice (I'm interested in large cubic lattices) with nodes n_i and edges e_ij.
2) For each edge e_ij, choose a gauge group variable g_ij and irreducible representation rho_ij.
3) For each node, choose an intertwiner t_i from the tensor product of the representations of the in-going edges and dual reps of the outgoing edges to the trivial representation.
4) Contract all the rho_ij(g_ij) with the corresponding t_i and t_j, so that the whole thing is contracted to a number.
5) The spin network state is the function of the g_ij that returns this number.

I'm interested in the cases with either arbitrary g_ij or, less ambitiously, with all the g_ij = 1 (i.e. a pure contraction of intertwiners). The number I want is the sum of the results for each specific choice of intertwiners, i.e. I sum the result over an orthonormal basis of intertwiners at each node.

At any rate, that's the function I want to evaluate, whether or not it's called a spin network state. For a large lattice, I figure it would take a computer a good while to assign all the rho_ij(g_ij) (Especially in SU(3), where the explicit parametrizations of arbitrary representations are rather complicated) , and another good while to contract all the rho_ij(g_ij) with the intertwiners.

I'd hugely appreciate any references to articles or textbooks, I've searched and searched but I've found only scattered hints. Thanks a lot for your time,
Michael McBreen

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