Yoshichika Iizuka

(飯塚義睦)

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Affiliation: Faculty of Science, Department of Mathematics, Gakushuin University

An Infinite Family of Pairs of Distinct Quartic Galois CM-fields with the Same Discriminant and Regulator

Yoshichika Iizuka, Yutaka Konomi

Tokyo Journal of Mathematics, 49(1) 225-237, Jun 1, 2026 Peer-reviewed

We construct an infinite family of pairs of distinct imaginary biquadratic fields and pairs of distinct imaginary cyclic quartic fields with the same discriminant and regulator. We also construct an infinite family of imaginary biquadratic fields and imaginary cyclic quartic fields with the same regulator. Moreover, we give examples of a pair of distinct imaginary biquadratic fields and a pair of distinct imaginary cyclic quartic fields with the same discriminant, regulator and class number.
An Application of the Arithmetic of Elliptic Curves to the Class Number Problem for Quadratic Fields

Yoshichika Iizuka, Yutaka Konomi, Shin Nakano

TOKYO JOURNAL OF MATHEMATICS, 44(1) 33-47, Jun, 2021 Peer-reviewed
On the class number divisibility of pairs of imaginary quadratic fields

Yoshichika Iizuka

JOURNAL OF NUMBER THEORY, 184 122-127, Mar, 2018 Peer-reviewed
On the class number divisibility of pairs of quadratic fields obtained from points on elliptic curves

Yoshichika Iizuka, Yutaka Konomi, Shin Nakano

JOURNAL OF THE MATHEMATICAL SOCIETY OF JAPAN, 68(2) 899-915, Apr, 2016 Peer-reviewed
A remark on the norm of a formal group over $\mathbf {Z}_p$

Yoshichika Iizuka

Proceedings of the Japan Academy, Series A, Mathematical Sciences, 80(5), May 1, 2004 Peer-reviewed