On a tower of Garcia and Stichtenoth

In 2003, Garcia and Stichtenoth constructed a recursive tower F = (Fn)n \geq 0 of algebraic function fields over the finite field Fq, where q = lr with r \geq 1 and l > 2 is a power of the characteristic of Fq. They also gave a lower bound for the limit of this tower. In this paper, we compute the exact value of the genus of the algebraic function field Fn/Fq for each n \geq 0. Moreover, we prove that when q = 2k, with k \geq 2, the limit of the tower F attains the lower bound given by Garcia and Stichtenoth.

On a tower of Garcia and Stichtenoth

In 2003, Garcia and Stichtenoth constructed a recursive tower F = (Fn)n \geq 0 of algebraic function fields over the finite field Fq, where q = lr with r \geq 1 and l > 2 is a power of the characteristic of Fq. They also gave a lower bound for the limit of this tower. In this paper, we compute the exact value of the genus of the algebraic function field Fn/Fq for each n \geq 0. Moreover, we prove that when q = 2k, with k \geq 2, the limit of the tower F attains the lower bound given by Garcia and Stichtenoth.

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  • Ballet S, Rolland R. Lower bounds on the class number of algebraic function fields defined over any finite field. J Th´ e or Nombres Bordeaux 2012; 24: 505–540.
  • Garcia A, Stichtenoth H. A tower of Artin-Schreier extensions of function fields attaining the Drinfeld-Vladut bound. Invent Math 1995; 121: 211–222.
  • Garcia A, Stichtenoth H, R¨ uck HG. On tame towers over finite fields. J Reine Angew Math 2003; 557: 53–80. Garcia A, Stichtenoth H, Thomas M. On towers and composita of towers of function fields over finite fields. Finite Fields Th App 1997; 3: 257–274.
  • Gerard VDG, Vlugt MVD. An asymptotically good tower of curves over the field with eight elements. B Lond Math Soc 2002; 34.03: 291–300.
  • Hess F, Stichtenoth H, Tutdere S. On invariants of towers of function fields over finite fields. J Algebra Appl 2013; 12 477–487.
  • Stichtenoth H. Algebraic Function Fields and Codes. 2nd ed. Berlin, Germany: Springer, 2009.
  • Tsfasman MA, Vladut SG, Zink T. Modular curves, Shimura curves and Goppa codes, better than the VarshamovGilbert bound. Math Nachr 1982; 109: 21–28.
  • Tutdere S. On the asymptotic theory of towers of function fields over finite fields. PhD, Sabancı University, ˙Istanbul, Turkey, 2012.
  • Wulftange J. Zahme T¨ urme algebraischer Funktionenk¨ orper. PhD, Essen University, Essen, Germany, 2002.