Dr. Gregory Natanson is an independent researcher. Degrees: MSc in Chemistry from Dept. of Chemistry, Leningrad State University (USSR); Ph.D. in Mathematical and Theoretical Physics, Dept. of Theoretical Physics, Leningrad State University (USSR). Work experience: 1971-1980: Senior Scientist; Leningrad Hydrometeorological Institute (USSR). Interests: turbulent diffusion of radioactive pollutants in atmosphere; theory of 1D Schrodinger equation; microwave spectra of molecules with internal rotation. 1981-1987. Postdoctoral studies in the Depts. of Chemistry at the University of Chicago and the Northwestern University, spectra of spherical-top molecules, particle-on-sphere model for the water molecule; melting of small clusters; theory of chemical reaction. 1990-2004. Computer Scientist, CSC, ground attitude support of NASA satellites. 2004-2015, Senior Computer Scientist, AI Solutions Inc., ground attitude support of NASA satellites. 2016–present. Independent Researcher. Solvable-by-polynomials rational extensions of shape-invariant potentials; theory of finite and infinite exceptional orthogonal polynomials.