Lorentz 2-orbifolds of constant non-zero curvature with the essential isometry group N. I. Zhukova, E. V. Bogolepova III International Conference “Mathematical Physics, Dynamical Systems, Infinite-Dimensional Analysis”, dedicated to the 100th anniversary of V.S. Vladimirov, the 100th anniversary of L.D. Kudryavtsev and the 85th anniversary of O.G. Smolyanov July 5, 2023 15:05