@article{17231,
  abstract     = {In the class of projective billiards, which contains the usual billiards, we exhibit counter-examples to Ivrii's conjecture, which states that in any planar billiard with smooth boundary the set of periodic orbits has zero measure. The counter-examples are polygons admitting a 2-parameters family of n-periodic orbits, with n being either 3 or any even integer greater than 4.},
  author       = {Fiorebe, Corentin},
  issn         = {1553-5231},
  journal      = {Discrete and Continuous Dynamical Systems- Series A},
  number       = {11},
  pages        = {3287--3301},
  publisher    = {American Institute of Mathematical Sciences},
  title        = {{Examples of projective billiards with open sets of periodic orbits}},
  doi          = {10.3934/dcds.2024059},
  volume       = {44},
  year         = {2024},
}