Now showing items 1-10 of 10
On component groups of Jo(N) and degeneracy maps
For an integer M >1 and a prime p ≥ 5 not dividing M, we study the kernel of the degeneracy map ΦʳMp,p --˃ ΦMpʳ,p, where ΦMp,p and ΦMpʳ,p are the component groups of J0(Mp) and J0(Mpʳ), respectively. This is then ...
On the rational cuspidal subgroup and the rational torsion points of Jo(pq)
For two distinct prime numbers p, q, we compute the rational cuspidal subgroup C(pq) of J0(pq) and determine the l-primary part of the rational torsion subgroup of the old subvariety of J0(pq) for most primes l.Some ...
Shimura subgroups of Jacobians of Shimura curves
Given an indefinite quaternion algebra of reduced discriminant D and an integer N relatively prime to D, one can construct Shimura curves Sh0(N, D) and Sh1(N, D), which are analogues of X0(N) and X1(N). The natural morphism ...
Almost perfect sequences with θ=2
Almost perfect sequences with θ=2 are studied in this paper. Recently Arasu, Ma and Voss  studied such sequences and they could only obtain sequences having periods 8, 12 and 28. In this paper, we prove that no other ...
Projective covering designs
A (2, k, v) covering design is a pair (X, F) such that X is a v-element set and F is a family of k-element subsets, called blocks, of X with the property that every pair of distinct elements of X is contained in at least ...
Combinatorial coverings from geometries over principal ideal rings
A t-(v, k, λ) covering is an incidence structure with v points, each block incident on exactly k points, such that every set of t distinct points is incident on at least λ blocks. By considering certain geometries over ...
Shimura subgroups and degeneracy maps
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 ...
The fitting ideal of J0(q)(Fpn) over the Hecke algebra
Abstract is not available.
Attack on RSA-type cryptosystems based on singular cubic curves over Z/nZ
Several RSA-type cryptosystems based on singular cubic curves have been proposed in recent years (cf. Koyama, Lecture notes in Computer Science, vol. 921, Springer, Berlin, 1995, pp. 329–339; Kuwakado, IEICE Trans. Fund. ...
Congruences between cusp forms and the geometry of Jacobians of modular curves
Abstract not available in fulltext.