Graduate Spin networks with different intertwiners

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Spin networks are characterized by their nodes and links, which are assigned SU(2) representations and intertwiners. An example is requested to illustrate two distinct spin networks that share the same structural elements but differ in their intertwiners. The discussion also touches on how to assign squarable complex-valued functions to these networks and the contraction of intertwiners with links. Additionally, the tensor product of two half-integer SU(2) representations is examined, revealing the emergence of multiple intertwiners at a four-valent node. There is also a query regarding issues with the LaTeX formula used in the discussion.
Heidi
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Hi Pfs
Spin networks are defined by the way their links and their nodes are equipped with SU(2) representations and intertwiners.
Could you give an example of two different spin networks with the same number of nodes, links between them, the same coloring of the links (and their orientations) but have different intertwiners?
I would like to see how to assign squarable complex valued functions to them. how the intertwiners contract with the links.
thanks
 
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if i take the tensor product of two half integer SU(2) representation on 2 dimensional Hilbert space, i get a 4 dimensional matrix with
##1/2 \otimes 1/2 = 0 + 1## and if i tensor it by it self i get the (0 + 1) + (1 + 0 + 1 + 2) representation with dimension 4 + 12 = 16. we see that 0 appears twice so there are two intertwiners. How do they act in the four valent node?
and what is the problem with the latex formula?
 
Time reversal invariant Hamiltonians must satisfy ##[H,\Theta]=0## where ##\Theta## is time reversal operator. However, in some texts (for example see Many-body Quantum Theory in Condensed Matter Physics an introduction, HENRIK BRUUS and KARSTEN FLENSBERG, Corrected version: 14 January 2016, section 7.1.4) the time reversal invariant condition is introduced as ##H=H^*##. How these two conditions are identical?

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