Emergent 3-manifolds from 4d Superconformal Indices
  We show that the smooth geometry of a hyperbolic 3-manifold emerges from a classical spin system defined on a 2d discrete lattice, and moreover show that the process of this "dimensional oxidation" is equivalent with the dimensional reduction of a supersymmetric gauge theory from 4d to 3d. More concretely, we propose an equality between (1) the 4d superconformal index of a 4d N=1 superconformal quiver gauge theory described by a bipartite graph on T^2 and the partition function of a classical integrable spin chain on T^2. The 2d spin system is lifted to a hyperbolic 3-manifold after the dimensional reduction and the Higgsing of the 4d gauge theory. 
Yuji Terashima and Masahito Yamazaki
hep-th math-ph math.GT math.MP