Uniform Distribution Theory
Journal license

Journal

Uniform Distribution Theory


Volume
& Issue

Volume 21, Issue 1


Published
on

November 3, 2026


Pages

1-8


DOI

Article

A concise geometric proof of the three distance theorem

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Authors

Tadahisa Hamada* Affiliation:
Institute of Mathematics, University of Tsukuba, Japan.


Abstract

The three distance theorem states that for any given irrational number \( \alpha \) and a natural number \( n \), when the interval \( (0,1) \) is divided into \( n+1 \) subintervals by integer multiples of \( \alpha \), namely, \( \{0\}, \{\alpha\}, \{2\alpha\}, \ldots, \{n\alpha\} \), then each subinterval is limited to at most three different lengths. Steinhaus conjectured this theorem in the 1950s, and many researchers have given various proofs since then.

This paper aims to improve the perspective by showing a two-dimensional map which tells how the unit interval is divided by continuously changing \( \alpha \), and provide a concise proof of the theorem. By illustrating this proof through geometric visualizations, we offer a clearer and more intuitive understanding of the underlying principles and relationships. The approach not only reinforces the classical results but also paves the way for new insights and applications in the study of irrational numbers and their properties.


Keywords

three distance theorem, three gap theorem, Farey sequence, Farey pair.


Citation

Hamada, T. (2026). A concise geometric proof of the three distance theorem. Uniform Distribution Theory, 21(1), 1–8. https://doi.org/10.66833/UDT-2026-0010

Published by: Engineering Journals

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