29 citations · 169 across the 49 of their papers we have counts for
50 papers
Involutions in the affine Conway group
Ichiro Shimada
The affine Conway group is the group of affine isometries of the Leech lattice. This group is isomorphic to the automorphism group of a standard fundamental domain for the action o…
Mordell-Weil groups and automorphism groups of elliptic K3 surfaces
Ichiro Shimada
We present a method to calculate the action of the Mordell-Weil group of an elliptic K3 surface on the numerical Néron-Severi lattice of the K3 surface. As an application, we compu…
Zariski multiples associated with quartic curves
Ichiro Shimada
We investigate Zariski multiples of plane curves such that each is a union of a smooth quartic curve, some of its bitangents, and some of its 4-tangent coni…
A note on Quebbemann's extremal lattices of rank 64
Ichiro Shimada
By constructing explicit examples, we show that the method of Quebbemann yields many isomorphism classes of extremal lattices of rank 64. Many of these examples have no non-trivial…
Automorphism groups of certain Enriques surfaces
Simon Brandhorst, Ichiro Shimada
We calculate the automorphism group of certain Enriques surfaces. The Enriques surfaces that we investigate include very general -nodal Enriques surfaces and very general cuspid…
On characteristic polynomials of automorphisms of Enriques surfaces
Simon Brandhorst, Sławomir Rams, Ichiro Shimada
Let be an automorphism of a complex Enriques surface and let denote the characteristic polynomial of the isometry of the numerical Néron-Severi lattice of i…