Abstract
Let K be the number field determined by a monic irreducible polynomial f(x) with integer coefficients. In previous papers we parameterized the prime ideals of K in terms of certain invariants attached to Newton polygons of higher order of f(x). In this paper we show how to carry out the basic operations on fractional ideals of K in terms of these constructive representations of the prime ideals. From a computational perspective, these results facilitate the manipulation of fractional ideals of K avoiding two heavy tasks: the construction of the maximal order of K and the factorization of the discriminant of f(x). The main computational ingredient is the Montes algorithm, which is an extremely fast procedure to construct the prime ideals.
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References
J.-D. Bauch, E. Nart, H.D. Stainsby, Complexity of OM factorizations of polynomials over local fields. arXiv:1204.4671v1 [math.NT].
R. Dedekind, Über den Zusammenhang zwischen der Theorie der Ideale und der Theorie der höheren Kongruenzen, Abh. K. Ges. Wiss. Göttingen 23, 1–23 (1878).
D. Ford, O. Veres, On the complexity of the Montes ideal factorization algorithm, in Algorithmic Number Theory, 9th International Symposium, ANTS-IX, Nancy, France, July 19–23, 2010, ed. by G. Hanrot, F. Morain, E. Thomé. LNCS (Springer, Berlin, 2010).
J. Guàrdia, J. Montes, E. Nart, Okutsu invariants and Newton polygons, Acta Arith. 145(1), 83–108 (2010).
J. Guàrdia, J. Montes, E. Nart, Higher Newton polygons in the computation of discriminants and prime ideal decomposition in number fields, J. Théor. Nr. Bordx. 23(3), 667–696 (2011).
J. Guàrdia, J. Montes, E. Nart, Newton polygons of higher order in algebraic number theory, Trans. Am. Math. Soc. 364(1), 361–416 (2012).
J. Guàrdia, J. Montes, E. Nart, Higher Newton polygons and integral bases. arXiv:0902.3428v3 [math.NT].
J. Guàrdia, J. Montes, E. Nart, Arithmetic in big number fields: The ‘+Ideals’ package. arXiv:1005.4596v1 [math.NT].
J. Guàrdia, E. Nart, S. Pauli, Single-factor lifting and factorization of polynomials over local fields, J. Symb. Comput. 47, 1318–1346 (2012).
K. Hensel, Theorie der Algebraischen Zahlen (Teubner, Leipzig, 1908).
F. Hess, Computing Riemann–Roch spaces in algebraic function fields and related topics, J. Symb. Comput. 33, 425–445 (2002).
S. MacLane, A construction for absolute values in polynomial rings, Trans. Am. Math. Soc. 40, 363–395 (1936).
S. MacLane, A construction for prime ideals as absolute values of an algebraic field, Duke Math. J. 2, 492–510 (1936).
J. Montes, Polígonos de Newton de Orden Superior y Aplicaciones Aritméticas, Tesi Doctoral, Universitat de Barcelona, 1999.
E. Nart, Local computation of differents and discriminants, Math. Comput., to appear. arXiv:1205.1340v1 [math.NT].
K. Okutsu, Construction of integral basis, I, II, Proc. Jpn. Acad., Ser. A, Math. Sci. 58, 47–49, 87–89 (1982).
Ø. Ore, Zur Theorie der algebraischen Körper, Acta Math. Djursholm 44, 219–314 (1923).
Ø. Ore, Bestimmung der Diskriminanten algebraischer Körper, Acta Math. Djursholm 45, 303–344 (1925).
Ø. Ore, Newtonsche Polygone in der Theorie der algebraischen Körper, Math. Ann. 99, 84–117 (1928).
S. Pauli, Factoring polynomials over local fields, II, in Algorithmic Number Theory, 9th International Symposium, ANTS-IX, Nancy, France, July 19–23, 2010, ed. by G. Hanrot, F. Morain, E. Thomé. LNCS (Springer, Berlin, 2010).
J. Rasmussen, personal communication.
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Research partially supported by MTM2009-13060-C02-02 and MTM2009-10359 from the Spanish MEC
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Communicated by Felipe Cucker.
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Guàrdia, J., Montes, J. & Nart, E. A New Computational Approach to Ideal Theory in Number Fields. Found Comput Math 13, 729–762 (2013). https://doi.org/10.1007/s10208-012-9137-5
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DOI: https://doi.org/10.1007/s10208-012-9137-5