Abstract
The seminal papers in the field of root-discriminant bounds are those of Odlyzko and Martinet. Both papers include the question of whether the field \(\mathbb {Q}(\sqrt{-5460})\) has finite or infinite 2-class tower. This is a critical case that will either substantially lower the best known upper bound for lim inf of root discriminants (if infinite) or else give a counter-example to what is often termed Martinet’s conjecture or question (if finite). Using extensive computation and introducing some new techniques, we give strong evidence that the tower is in fact finite, establishing other properties of its Galois group en route.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
E.Benjamin, On imaginary quadratic number fields with \(2\)-class group of rank \(4\) and infinite \(2\)-class field tower, Pacific J. Math. 201 (2001), 257–266.
E.Benjamin, On a question of Martinet concerning the \(2\)-class field tower of imaginary quadratic number fields, Ann. Sci. Math. Quebec 26 (1) (2002), 1–13.
E.Benjamin, On the \(2\)-class field tower conjecture for imaginary quadratic number fields with \(2\)-class group of rank \(4\), J. Number Theory 154 (2015), 118–143.
W.Bosma, J.J.Cannon, and C.Playoust, The Magma algebra system. I. The user language, J.Symbolic Comput. 24 (1997), 235–265.
N.Boston and H.Nover, Computing pro-\(p\) Galois groups, Lecture Notes in Computer Science 4076 (2006), ANTS VII, 1–10.
M.R.Bush, Computation of the Galois groups associated to the 2-class towers of some quadratic fields, J. Number Theory 100 (2003), 313–325.
J.-M.Fontaine and B.C.Mazur, Geometric Galois representations, Elliptic curves, modular forms, & Fermat’s last theorem (Hong Kong, 1993), Series in Number Theory, 1, Int. Press, Cambridge, MA, 41–78.
A.Fröhlich, Central extensions, Galois groups, and ideal class groups of number fields, Contemporary Mathematics 24, AMS (1983).
E.S.Golod and I.R.Shafarevich, On the class field tower (Russian), Izv. Akad. Nauk SSSR Ser. Mat. 28 (1964), 261–272; English translation in AMS Transl. 48 (1965), 91–102.
F.Hajir and C.Maire, Tamely ramified towers and discriminant bounds for number fields. II., J. Symbolic Comput. 33 (2002), 415–423.
G.Havas, M.F.Newman, and E.A.O’Brien, On the efficiency of some finite groups, Comm. Algebra 32 (2004), 649–656.
H.Koch, Galois theory of \(p\)-extensions, Springer Monographs in Mathematics. Springer-Verlag, Berlin (2002).
C.R.Leedham-Green, The structure of finite \(p\)-groups, J. London Math. Soc. 50 (1) (1994), 49–67.
A.Lubotzky and A.Mann, Powerful \(p\)-groups. II. \(p\)-adic analytic groups, J. Algebra 105 (2) (1987), 506–515.
J.Martinet, Tours de corps de classes et estimations de discriminants (French), Invent Math 44 (1978), 65–73.
A.Mouhib, Infinite Hilbert \(2\)-class field tower of quadratic number fields, Acta Arith. 145 (3) (2010), 267–272.
H.Nover, Computation of Galois groups associated to the \(2\)-class towers of some imaginary quadratic fields with \(2\)-class group \(C_2 \times C_2 \times C_2\), J. Number Theory 129 (1) (2009), 231–245.
E.A.O’Brien, The \(p\)-group generation algorithm, J. Symbolic Comput. 9 (1990), 677–698.
A.Odlyzko, Lower bounds for discriminants of number fields, Acta Arith. 29 (1976), 275–297.
D.J.S.Robinson, A course in the theory of groups, Springer-Verlag, Berlin (1982).
I.R.Shafarevich, Extensions with prescribed ramification points (Russian), IHES Publ. 18 (1963), 71–95; English translation in I.R.Shafarevich, Collected Mathematical Papers, Springer, Berlin (1989).
A.Shalev, The structure of finite p-groups: effective proof of the coclass conjectures, Invent. Math. 115 (2) (1994), 315–345.
Y.Sueyoshi, Infinite \(2\)-class field towers of some imaginary quadratic number fields, Acta Arith. 113 (3) (2004), 251–257.
Y.Sueyoshi, On \(2\)-class field towers of imaginary quadratic number fields, Far East J. Math. Sci. (FJMS) 34 (3) (2009), 329–339.
Y.Sueyoshi, On the infinitude of \(2\)-class field towers of some imaginary quadratic number fields, Far East J. Math. Sci. (FJMS) 42 (2) (2010), 175–187.
V.Y.Wang, On Hilbert \(2\)-class fields and \(2\)-towers of imaginary quadratic number fields, arXiv:1508.06552.
Acknowledgements
The authors thank Charles Leedham-Green for his comments on the paper. The first author was supported by Simons Foundation Award MSN-179747. The second author was supported by National Science Foundation grant DMS-1301690.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2018 Springer Nature Switzerland AG
About this paper
Cite this paper
Boston, N., Wang, J. (2018). The 2-Class Tower of \(\mathbb {Q}(\sqrt{-5460})\). In: Akbary, A., Gun, S. (eds) Geometry, Algebra, Number Theory, and Their Information Technology Applications. GANITA 2016. Springer Proceedings in Mathematics & Statistics, vol 251. Springer, Cham. https://doi.org/10.1007/978-3-319-97379-1_5
Download citation
DOI: https://doi.org/10.1007/978-3-319-97379-1_5
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-97378-4
Online ISBN: 978-3-319-97379-1
eBook Packages: Mathematics and StatisticsMathematics and Statistics (R0)