Symmetry and folding of continued fractions
Journal de théorie des nombres de Bordeaux, Volume 14 (2002) no. 2, p. 603-611

Michel Mendès France's “Folding Lemma” for continued fraction expansions provides an unusual explanation for the well known symmetry in the expansion of a quadratic irrational integer.

Le «lemme de pliage» de Michel Mendès France fournit une nouvelle justification de la symétrie du développement en fraction continue d'un irrationnel quadratique.

@article{JTNB_2002__14_2_603_0,
     author = {van der Poorten, Alferd J.},
     title = {Symmetry and folding of continued fractions},
     journal = {Journal de th\'eorie des nombres de Bordeaux},
     publisher = {Universit\'e Bordeaux I},
     volume = {14},
     number = {2},
     year = {2002},
     pages = {603-611},
     zbl = {1067.11001},
     mrnumber = {2040696},
     language = {en},
     url = {http://www.numdam.org/item/JTNB_2002__14_2_603_0}
}
Van der Poorten, Alfred J. Symmetry and folding of continued fractions. Journal de théorie des nombres de Bordeaux, Volume 14 (2002) no. 2, pp. 603-611. http://www.numdam.org/item/JTNB_2002__14_2_603_0/

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