NESTED PROPERTIES. “The full symmetry picture is quite intricate, since the configuration of the obstacles have nested geometrical qualities. For a double-slit, there are single slits at the foci, and for a single slit, there are edges at the foci. In addition, an elliptic transformation does not give a diffeomorphism for the line between the foci.”
https://link.springer.com/content/pdf/10.1007/JHEP07(2019)140.pdf