Gras conjecture

In algebraic number theory, the Gras conjecture (Gras 1977) relates the p-parts of the Galois eigenspaces of an ideal class group to the group of global units modulo cyclotomic units. It was proved by Mazur & Wiles (1984) as a corollary of their work on the main conjecture of Iwasawa theory. Kolyvagin (1990) later gave a simpler proof using Euler systems.

References

• Gras, Georges (1977), "Classes d'idéaux des corps abéliens et nombres de Bernoulli généralisés", Université de Grenoble. Annales de l'Institut Fourier 27 (1): 1–66, ISSN 0373-0956, MR0450238, http://aif.cedram.org/item?id=AIF_1977__27_1_1_0 
• Kolyvagin, V. A. (1990), "Euler systems", The Grothendieck Festschrift, Vol. II, Progr. Math., 87, Boston, MA: Birkhäuser Boston, pp. 435–483, doi:10.1007/978-0-8176-4575-5_11, ISBN 978-0-8176-3428-5, MR1106906 
• Mazur, Barry; Wiles, Andrew (1984), "Class fields of abelian extensions of Q", Inventiones Mathematicae 76 (2): 179–330, doi:10.1007/BF01388599, ISSN 0020-9910, MR742853