Subdivided constraints and physical identifications

Realize the theta graph as three closed arcs joining two vertices. At scale $n$, divide each arc into $m_n=2^n$ links. Use the Gauss constraints (eq:gauss) at the original vertices and all new degree-two vertices.

At a degree-two vertex, the physical $X$-eigenvalues of its two incident links must agree. Hence all sublinks of one original arc have a common eigenvalue. The two original endpoint constraints require that the product of the three arc eigenvalues be one.