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The Modularity Theorem

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Quadratic Number Fields

Abstract

This chapter presents the quadratic reciprocity law and the modularity of Kronecker characters and applies the results to Terjanian’s theorem on the Fermat equation of exponent 2p.

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Notes

  1. 1.

    Beginners in mathematics may find it hard to believe that mathematicians think of finite fields (and even p-adic numbers) as being simpler objects than integers. One possible way of measuring the simplicity of structures A and B is counting homomorphisms from A and B into structures C. For example, there are many homomorphisms from \({\mathbb Z}\) to finite fields \({\mathbb F}_p\), whereas the only homomorphisms from \({\mathbb F}_p\) to \({\mathbb Z}\) or to finite fields are either the trivial homomorphism mapping everything to 0 or (in the case of \({\mathbb F}_p \longrightarrow {\mathbb F}_p\)) an isomorphism.

  2. 2.

    See [136] and [41]; our presentation is a simplification of the one given in [62].

  3. 3.

    This proof is essentially due to Frobenius [41].

  4. 4.

    See, e.g., [36].

  5. 5.

    This proof is lifted from Davenports beautiful book [27]; its basic idea goes back to the proof given by Arnold Scholz in [112].

  6. 6.

    See the beautiful article [24] by Cosgrave and Dilcher for an introduction to such congruences.

  7. 7.

    There is a misprint in Terjanian [121, Equation (2)].

References

  1. J.H. Bruinier, G. van der Geer, G. Harder, D. Zagier, The 1-2-3 of Modular Forms (Springer, New York, 2008)

    Book  Google Scholar 

  2. W. Castryck, A shortened classical proof of the quadratic reciprocity law. Am. Math. Monthly 115, 550–551 (2008)

    Article  MathSciNet  Google Scholar 

  3. H.H. Chan, L. Long, Y. Yang, A cubic analogue of the Jacobsthal identity. Am. Math. Monthly 118, 316–326 (2011)

    Article  MathSciNet  Google Scholar 

  4. J.B. Cosgrave, K. Dilcher, An Introduction to Gauss Factorials, Am. Math. Monthly 118, 812–829 (2011)

    Article  MathSciNet  Google Scholar 

  5. H. Davenport, The Higher Arithmetic, 8th edn. (Cambridge University Press, Cambridge, 2008)

    Book  Google Scholar 

  6. G. Eisenstein, Neuer und elementarer Beweis des Legendre’schen Reciprocitäts-Gesetzes. J. Reine Angew. Math. 27, 322–329 (1844); Math. Werke I, 100–107

    Google Scholar 

  7. L. Euler, Theoremata circa divisores numerorum in hac forma paa ± qbb contentorum. Commun. Acad. Sci. Petropol. 14, 151–158 (1751); Opera Omnia I - 2, 194–222

    Google Scholar 

  8. F.G. Frobenius, Über das quadratische Reziprozitätsgesetz I, Sitzungsberichte Berliner Akad. 335–349 (1914). Ges. Abhandl. 628–642

    Google Scholar 

  9. K. Hashimoto, L. Long, Y. Yang, Jacobsthal identity for\({\mathbb Q}(\sqrt {-2}\,)\), Forum Math. 24, 1225–1238 (2012)

    Google Scholar 

  10. F. Hirzebruch, D. Zagier, The Atiyah-Singer Theorem and Elementary Number Theory (Publish or Perish, Boston, 1974)

    MATH  Google Scholar 

  11. K. Ireland, K. Rosen, A Classical Introduction to Modern Number Theory (Springer, New York, 1990)

    Book  Google Scholar 

  12. E. Jacobsthal, Anwendungen einer Formel aus der Theorie der quadratischen Reste, Diss., Berlin, 1906

    MATH  Google Scholar 

  13. E. Jacobsthal, Über die Darstellung der Primzahlen der Form 4n + 1 als Summe zweier Quadrate. J. Reine Angew. Math. 132, 238–246 (1907)

    MathSciNet  MATH  Google Scholar 

  14. L. Kronecker, Ueber die Potenzreste gewisser complexer Zahlen (Monatsber, Berlin, 1880), pp. 404–407; Werke II, 95–101

    Google Scholar 

  15. V.A. Lebesgue, Recherches sur les nombres. J. Math. Pures Appl. 3, 113–144 (1838)

    Google Scholar 

  16. F. Lemmermeyer, Parametrization of algebraic curves from a number theorist’s point of view. Am. Math. Monthly 119, 573–583 (2012)

    Article  MathSciNet  Google Scholar 

  17. M.G. Monzingo, An elementary evaluation of the Jacobsthal sum. J. Number Theory 22, 21–25 (1986)

    Article  MathSciNet  Google Scholar 

  18. A. Scholz, EinfĂĽhrung in die Zahlentheorie (de Gruyter, Berlin, 1939)

    MATH  Google Scholar 

  19. G. Terjanian, Sur l’équation x 2p + y 2p = z 2p. C. R. Acad. Sci. Paris 285, 973–975 (1977)

    MathSciNet  MATH  Google Scholar 

  20. L. von Schrutka, Ein Beweis für die Zerlegbarkeit der Primzahlen von der Form 6n + 1 in ein einfaches und ein dreifaches Quadrat. J. Reine Angew. Math. 140, 252–265 (1911)

    Article  MathSciNet  Google Scholar 

  21. A. Widmer, Über die Anzahl der Lösungen gewisser Kongruenzen nach einem Primzahlmodul, Diss. ETH Zurich, 1919

    Google Scholar 

  22. Ch. Zeller, Beweis des Reciprocitätsgesetzes für die quadratischen Reste (Monatsber, Berlin, 1872), pp. 846–847

    MATH  Google Scholar 

  23. G. Zolotareff, Nouvelle démonstration de la loi de réciprocité de Legendre. Nouv. Ann. Math (2) 11, 354–362 (1872)

    Google Scholar 

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Lemmermeyer, F. (2021). The Modularity Theorem. In: Quadratic Number Fields. Springer Undergraduate Mathematics Series. Springer, Cham. https://doi.org/10.1007/978-3-030-78652-6_3

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