The size function for quadratic extensions of complex quadratic fields
Journal de théorie des nombres de Bordeaux, Tome 29 (2017) no. 1, pp. 243-259.

La fonction h 0 pour un corps de nombre est un analogue de la dimension des espaces vectoriels de Riemann–Roch des diviseurs sur une courbe algébrique. Dans cet article, nous montrons une conjecture de van der Geer et Schoof sur la maximalité de h 0 au diviseur d’Arakelov trivial pour les extensions quadratiques de corps quadratiques imaginaires.

The function h 0 for a number field is an analogue of the dimension of the Riemann–Roch spaces of divisors on an algebraic curve. In this paper, we prove the conjecture of van der Geer and Schoof about the maximality of h 0 at the trivial Arakelov divisor for quadratic extensions of complex quadratic fields.

Reçu le :
Accepté le :
Publié le :
DOI : 10.5802/jtnb.978
Classification : 11R16, 11R11, 11R55, 11R40
Mots clés : Arakelov divisor, effectivity divisor, size function, $h^0$, line bundle
Tran, Ha Thanh Nguyen 1

1 Department of Mathematics and Systems Analysis, Aalto University School of Science, Otakaari 1, 02150 Espoo, Finland
@article{JTNB_2017__29_1_243_0,
     author = {Tran, Ha Thanh Nguyen},
     title = {The size function for quadratic extensions of complex quadratic fields},
     journal = {Journal de th\'eorie des nombres de Bordeaux},
     pages = {243--259},
     publisher = {Soci\'et\'e Arithm\'etique de Bordeaux},
     volume = {29},
     number = {1},
     year = {2017},
     doi = {10.5802/jtnb.978},
     language = {en},
     url = {http://archive.numdam.org/articles/10.5802/jtnb.978/}
}
TY  - JOUR
AU  - Tran, Ha Thanh Nguyen
TI  - The size function for quadratic extensions of complex quadratic fields
JO  - Journal de théorie des nombres de Bordeaux
PY  - 2017
SP  - 243
EP  - 259
VL  - 29
IS  - 1
PB  - Société Arithmétique de Bordeaux
UR  - http://archive.numdam.org/articles/10.5802/jtnb.978/
DO  - 10.5802/jtnb.978
LA  - en
ID  - JTNB_2017__29_1_243_0
ER  - 
%0 Journal Article
%A Tran, Ha Thanh Nguyen
%T The size function for quadratic extensions of complex quadratic fields
%J Journal de théorie des nombres de Bordeaux
%D 2017
%P 243-259
%V 29
%N 1
%I Société Arithmétique de Bordeaux
%U http://archive.numdam.org/articles/10.5802/jtnb.978/
%R 10.5802/jtnb.978
%G en
%F JTNB_2017__29_1_243_0
Tran, Ha Thanh Nguyen. The size function for quadratic extensions of complex quadratic fields. Journal de théorie des nombres de Bordeaux, Tome 29 (2017) no. 1, pp. 243-259. doi : 10.5802/jtnb.978. http://archive.numdam.org/articles/10.5802/jtnb.978/

[1] Bayer-Fluckiger, Eva Lattices and number fields, Algebraic geometry: Hirzebruch 70 (Warsaw, 1998) (Contemp. Math., Amer. Math. Soc.), Volume 241, Providence, RI (1999), pp. 69-84

[2] Cohen, Henri A course in computational algebraic number theory, Graduate Texts in Mathematics, 138, Springer-Verlag, Berlin, 1993, xxi+534 pages

[3] Fincke, U.; Pohst, M. Improved methods for calculating vectors of short length in a lattice, including a complexity analysis, Math. Comp., Volume 44 (1985), pp. 463-471 | DOI

[4] Ford, D. Enumeration of totally complex quartic fields of small discriminant, Computational number theory (Debrecen, 1989), de Gruyter, Berlin (1991), pp. 129-138

[5] Francini, Paolo The size function h 0 for quadratic number fields, J. Théor. Nombres Bordeaux, Volume 13 (2001) no. 1, pp. 125-135 21st Journées Arithmétiques (Rome, 2001) | DOI

[6] Francini, Paolo The size function h for a pure cubic field, Acta Arith., Volume 111 (2004) no. 3, pp. 225-237 | DOI

[7] van der Geer, Gerard; Schoof, René Effectivity of Arakelov divisors and the theta divisor of a number field, Selecta Math. (N.S.), Volume 6 (200) no. 4, pp. 377-398

[8] Groenewegen, R. P. The size function for number fields, Universiteit van Amsterdam (The Netherlands) (1999) (Ph. D. Thesis)

[9] Groenewegen, R. P. An arithmetic analogue of Clifford’s theorem, J. Théor. Nombres Bordeaux, Volume 13 (2001) no. 1, pp. 143-156 21st Journées Arithmétiques (Rome, 2001) | DOI

[10] Lenstra, Hendrik W. Jr. Lattices, Algorithmic number theory: lattices, number fields, curves and cryptography (Math. Sci. Res. Inst. Publ.), Volume 44, Cambridge Univ. Press, 2008, pp. 127-181

[11] Pohst, Michael Regulatorabschätzungen für total reelle algebraische Zahlkörper, J. Number Theory, Volume 9 (1977), pp. 459-492 | DOI

[12] Schoof, René Computing Arakelov class groups, Algorithmic number theory: lattices, number fields, curves and cryptography (Math. Sci. Res. Inst. Publ.), Volume 44, Cambridge Univ. Press, 2008, pp. 447-495

Cité par Sources :