Ryotaro Sakamoto

collaborators

3 papers

math.CO2026

Root lattices over totally real fields

Ryotaro Sakamoto, Miyu Suzuki, Hiroyoshi Tamori

A root lattice is a finite rank $Z$ -lattice generated by elements $x$ satisfying $x \cdot x = 2$ . It is well-known that the root lattices have an $A D E$ classification and the…

math.NT2026

$p$ -Ordinary Part of Hyperbolic Cycles on Modular Curves

Hohto Bekki, Ryotaro Sakamoto

In this paper, we study hyperbolic cycles in the first homology group with local coefficients of congruence subgroups of $SL_{2} (Z)$ . We prove that, for any prime n…

math.NT2024

Harder's denominator problem for $SL_{2} (Z)$ and its applications

Hohto Bekki, Ryotaro Sakamoto

The aim of this paper is to give a full detail of the proof given by Harder of a theorem on the denominator of the Eisenstein class for $SL_{2} (Z)$ and to show that…

Root lattices over totally real fields

p-Ordinary Part of Hyperbolic Cycles on Modular Curves

Harder's denominator problem for SL2​(Z) and its applications

$p$ -Ordinary Part of Hyperbolic Cycles on Modular Curves

Harder's denominator problem for $SL_{2} (Z)$ and its applications