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Erdős problem 769

For the least cutoff c(n)c(n) after which every kk occurs as the number of homothetic cubes in a decomposition of the unit nn-cube, is c(n)≫nnc(n) \gg n^n? The Lean proof shows c(n)=o(nn)c(n) = o(n^n) along odd dimensions.

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FormalConjectures/ErdosProblems/

769.lean

Retained formal statement1 of 2

Let c(n)c(n) be minimal such that if k≥c(n)k\geq c(n) then the nn-dimensional unit cube can be decomposed into kk homothetic nn-dimensional cubes. Give good bounds for c(n)c(n) — in particular, is it true that c(n)≫nnc(n)\gg n^n?

The c(n) \gg n^n conjecture is false: for odd n, one can tile the unit n-cube into k homothetic cubes for every k ≥ U(n) with U(n)/n^n → 0, so c(n)/n^n → 0 along odd dimensions and no absolute constant lower-bounds it.

Determining good bounds for c(n) in general remains open.

FormalConjectures/ErdosProblems/769.leanErdos769.erdos_7691 lineExact file
False ↔ Erdos769.Erdos769LowerBound
SolvedProof has a holelean4external proof

The proof uses `sorry`: part of the argument is written but not proved. Lean accepts the file; it does not accept the theorem.