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Erdős problem 955

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If A⊂NA\subset \mathbb{N} has density 00 then s−1(A)s^{-1}(A) must also have density 00.

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The source's own material, retained exactly.

12 retained statements36c6d0fef71a

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FormalConjectures/ErdosProblems/

955.lean

Retained formal statement6 of 12

Troupe [Tr20] has also shown this is true if AA is the set of integers which are the sum of two squares.

FormalConjectures/ErdosProblems/955.leanErdos955.erdos_955.variants.troupe_sum_of_two_squares1 lineExact file
{x | ∃ a b, Erdos955.s x = a ^ 2 + b ^ 2}.HasDensity 0
SolvedStatement only, no proof