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Besicovitch sets

A Besicovitch (Kakeya) set contains a unit line segment in every direction, yet can have arbitrarily small area. This shows the classic Perron-tree construction: a triangle is repeatedly split and its halves slid over each other, so the 2n pieces still point in all directions but overlap more and more. Increase n and push α toward 1 to watch the area shrink.

A modern JavaScript + Canvas port of a 1998 Java applet by Terence Tao (originally Besicovitch.java / Kakeya.java).

Iterations n6
2ⁿ triangles
Overlap α0.80
upper bound for the area (α2n + (1 − α)) — a segment still points in every direction