---
res:
  bibo_abstract:
  - We prove some recent experimental observations of Dan Reznik concerning periodic
    billiard orbits in ellipses. For example, the sum of cosines of the angles of
    a periodic billiard polygon remains constant in the 1-parameter family of such
    polygons (that exist due to the Poncelet porism). In our proofs, we use geometric
    and complex analytic methods.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Arseniy
      foaf_name: Akopyan, Arseniy
      foaf_surname: Akopyan
      foaf_workInfoHomepage: http://www.librecat.org/personId=430D2C90-F248-11E8-B48F-1D18A9856A87
    orcid: 0000-0002-2548-617X
  - foaf_Person:
      foaf_givenName: Richard
      foaf_name: Schwartz, Richard
      foaf_surname: Schwartz
  - foaf_Person:
      foaf_givenName: Serge
      foaf_name: Tabachnikov, Serge
      foaf_surname: Tabachnikov
  bibo_doi: 10.1007/s40879-020-00426-9
  bibo_issue: '4'
  bibo_volume: 8
  dct_date: 2022^xs_gYear
  dct_isPartOf:
  - http://id.crossref.org/issn/2199-675X
  - http://id.crossref.org/issn/2199-6768
  dct_language: eng
  dct_publisher: Springer Nature@
  dct_title: Billiards in ellipses revisited@
...