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The one you saw on the blackboard may also be the Smith chart: https://en.wikipedia.org/wiki/Smith_chart

Is the Poincaré disk, a compact hyperbolic 2-d manifold. A space with negative curvature and maximal symmetry, the equivalent of a sphere but with negative curvature if you will.

You may have seen something similar in holography and AdS/CFT context. Or in an Escher painting.

Subdivisions of the hyperbolic plane. Propably more for the patterns then physics here.