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(a) We consider the regular tessellation of the hyperbolic plane with heptagons, embedded into the Poincaré disk with a hyperbolic metric. All neighboring lattice sites have equal hyperbolic distance and the unit disk boundary is infinitely far away from each point in the interior. (b) Finite graphs preserving sevenfold rotation invariance can be constructed by considering subsets that are topologically equivalent to ℓ = 1, 2, 3 … concentric rings, shown here for ℓ = 3.
