Shimura subgroups and degeneracy maps
Date of Issue1995
School of Physical and Mathematical Sciences
For M ≥ 1 an integer and M′ a positive divisor of M, let φ: J0(M′)τ → J0(M) be the map defined by all the degeneracy maps, where τ is the number of positive divisors of M/M′. We determine the kernel of φ for certain M and M′, as well as relate the pre-image of the Shimura subgroup Σ(M) under φ to the group Σ(M′)τ. We also study the restriction of degeneracy maps to Shimura subgroups.
Journal of number theory
© 1995 Academic Press. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Number Theory, Academic Press. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1006/jnth.1995.1100].