Sets that contain their circle centers

dc.creatorMartin, Greg
dc.date2007-03-29
dc.date.accessioned2026-07-07T07:55:02Z
dc.date.available2026-07-07T07:55:02Z
dc.descriptionSay that a subset S of the plane is a "circle-center set" if S is not a subset of a line, and whenever we choose three noncollinear points from S, the center of the unique circle through those three points is also an element of S. A problem appearing on the Macalester College Problem of the Week website was to prove that a finite set of points in the plane, no three lying on a common line, cannot be a circle-center set. Various solutions to this problem that did not use the full strength of the hypotheses appeared, and the conjecture was subsequently made that every circle-center set is unbounded. In this article, we prove a stronger assertion, namely that every circle-center set is dense in the plane, or equivalently that the only closed circle-center set is the entire plane. Along the way we show connections between our geometrical method of proof and number theory, real analysis, and topology.
dc.description12 pages, 4 figures
dc.identifierhttps://arxiv.org/abs/math/0703860
dc.identifierhttp://arxiv.org/abs/math/0703860
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/126835
dc.subjectMetric Geometry
dc.subject51M04
dc.titleSets that contain their circle centers
dc.typetext

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