Abstract
The article studies a generalization of the elliptic billiard to the complex domain. We show that the billiard orbits also have caustics, and that the number of such caustics is bigger than for the real case. For example, for a given ellipse E, there exist exactly two confocal ellipses such that the triangular orbits of E are circumscribed about one of them, and each tangent line to one of those ellipses is a side of a triangular orbit. In the case of 4-periodic orbits, we get generically three caustics. We also give an upper bound on the number of caustics for orbits with a fixed number of sides, and explain how to compute its exact value.
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References
Adabrah, A., Dragovic, V., Radnovic, M.: Periodic billiards within conics in the Minkowski plane and Akhiezer polynomials. Regul. Chaotic Dyn. 24(5), 464–501 (2019)
Akopyan, A., Schwartz, R., Tabachnikov, S.: Billiards in ellipses revisited. arXiv: 2001.02934
Bialy, M., Tabachnikov, S.: Dan Reznik’s identities and more. arXiv: 2001.08469
Berger, M.: Géométrie. Nathan, Paris (1990)
Chipalkatti, J.: On the Poncelet triangle condition over finite fields. Finite Fields Appl. 45, 59–72 (2017)
Dragovic, V., Radnovic, M.: Ellipsoidal billiards in pseudo-Euclidean spaces and relativistic quadrics. Adv. Math. 231, 1173–1201 (2012)
Dragovic, V., Radnovic, M.: Caustics of poncelet polygons and classical extremal polynomials. Regul. Chaotic Dyn. 24(1), 1–35 (2019)
Fierobe, C.: Examples of reflective projective billiards and outer ghost billiards, preprint. arXiv: 2002.09845
Flatto, L.: Poncelet’s Theorem. American Mathematical Society, Providence (2008)
Glutsyuk, A.: On quadrilateral orbits in complex algebraic planar billiards. Moscow Math. J. 14, 239–289 (2014)
Glutsyuk, A.: On odd-periodic orbits in complex planar billiards. J. Dyn. Control Syst. 20, 293–306 (2014)
Glutsyuk, A.: On 4-reflective complex analytic billiards. J. Geom. Anal. 27, 183–238 (2017)
Griffiths, Ph, Harris, J.: Cayley’s explicit solution to Poncelet’s porism. L’Enseignement Mathématiques 24, 31–40 (1978)
Hungerbühler, N., Kusejko, K.: A Poncelet Criterion for special pairs of conics in \(PG(2,p)\). arXiv:1409.3035 [math.CO]
Khesin, B., Tabachnikov, S.: Pseudo-Riemannian geodesics and billiards. Adv. Math. 221(4), 1364–1396 (2009)
Kozlov, V.V., Treshchev, D.V.: Billiards: A Genetic Introduction to the Dynamics of Systems with Impacts. Translations of Mathematical Monographs, vol. 89. American Mathematical Society, Providence (1991)
Krattenthaler, C.: Advanced determinant calculus: a complement. Linear Algebra Appl. 411, 68–166 (2005)
Reznik, D., Koiller, J.: https://github.com/dan-reznik/Elliptical-Billiards-Triangular-Orbits (2019)
Romaskevich, O.: On the incenters of triangular orbits in elliptic billiard. L’Enseignement Mathématiques 60, 247–255 (2014)
Tabachnikov, S.: Introducing projective billiards. Ergod. Theory Dyn. Syst. 17, 957–976 (1997)
Tabachnikov, S.: Exact transverse line fields and projective billiards in a ball. GAFA Geom. Funct. Anal. 7, 594–608 (1997)
Tabachnikov, S.: Geometry and billiards. Student Mathematical Library (2005) 30
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Fierobe, C. Complex Caustics of the Elliptic Billiard. Arnold Math J. 7, 1–30 (2021). https://doi.org/10.1007/s40598-020-00152-w
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DOI: https://doi.org/10.1007/s40598-020-00152-w