2003/06/08 by Terence Tao, Tao, Terence · 7 citations
Mathematics · #Advanced Algebra and Geometry #Algebraic and Geometric Analysis #Mathematical Analysis and Transform Methods #math.CA #math.CO #msc:20K01 #msc:42B99
paper · pdf · doi:10.48550/arxiv.math/0306134
8 pages, no figures, 2 matrices; submitted, Math Research Letters
arxiv created 2003/06/09 · arxiv updated 2009/11/30
We give an example of a set Ω⊂ \R5 which is a finite union of unit cubes, such that L2(Ω) admits an orthonormal basis of exponentials \\frac1|Ω|1/2 e2πi ξj ⋅ x: ξj ∈ Λ\ for some discrete set Λ⊂ \R5, but which does not tile \R5 by translations. This answers a conjecture of Fuglede in the negative, at least in 5 and higher dimensions.