Isosceles trapezoids of unit area with vertices in sets of infinite planar measure

Paul Erdős posed the question of whether every measurable planar set of infinite Lebesgue measure contains the four vertices of an isosceles trapezoid of unit area. In this paper, we provide an affirmative answer to this question. Additionally, we present affirmative solutions to similar questions by Erdős concerning isosceles triangles and right-angled triangles.

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Publication Details

Journal
Proceedings of the American Mathematical Society
Published
2025-08-29
DOI
https://doi.org/10.1090/proc/17322
Citations
1
Primary Topic
Advanced Mathematical Modeling in Engineering
Type
article
Field-Weighted Citation Impact
1.50
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article

Isosceles trapezoids of unit area with vertices in sets of infinite planar measure

Junnosuke Koizumi
1 citations
Proceedings of the American Mathematical Society
Advanced Mathematical Modeling in Engineering
1.50
article

Isosceles trapezoids of unit area with vertices in sets of infinite planar measure

Junnosuke Koizumi
article en
1 citations

Abstract

Paul Erdős posed the question of whether every measurable planar set of infinite Lebesgue measure contains the four vertices of an isosceles trapezoid of unit area. In this paper, we provide an affirmative answer to this question. Additionally, we present affirmative solutions to similar questions by Erdős concerning isosceles triangles and right-angled triangles.

Proceedings of the American Mathematical Society
Nippon Soken (Japan) (JP), RIKEN (JP)
Openalex Percentile: Top 14%
Advanced Mathematical Modeling in Engineering
1.50
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Isosceles trapezoids of unit area with vertices in sets of infinite planar measure — Junnosuke Koizumi · Proceedings of the American Mathematical Society (2025) | TGRS Research Map | TGRS