Abstract
We construct a convex set A with cardinality 2n and with the property that an element of the difference set \(A-A\) can be represented in n different ways. We also show that this construction is optimal by proving that for any convex set A, the maximum possible number of representations an element of \(A-A\) can have is \(\lfloor |A|/2 \rfloor\).
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Acknowledgements
We are grateful to Brandon Hanson, Misha Rudnev and Dmitrii Zhelezov for helpfully sharing their insights. We are particularly grateful to Ilya Shkredov for informing us about the reference [5].
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The authors were supported by the Austrian Science Fund FWF Project P 34180.
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Roche-Newton, O., Warren, A. A convex set with a rich difference. Acta Math. Hungar. 168, 587–592 (2022). https://doi.org/10.1007/s10474-022-01286-3
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DOI: https://doi.org/10.1007/s10474-022-01286-3