A set A of non-zero integers is called sum-free if for all choices of [itex] a,b\in A[/itex], a+b is not contained in A.(adsbygoogle = window.adsbygoogle || []).push({});

The Challenge: Find a constant c > 0 such that for every finite set of integers B not containing 0, there is a subset A of B such that A is sum-free and |A| ≥ c|B|, where |A| means the number of elements of A.

Every solution (by a new poster) which improves on the best constant known up until that point in the thread will be awarded a fresh 2 points, and of course alternate solutions which do not improve on the best known constant are more than welcome as well! Solutions which show a c exists but do not calculate it are also OK.

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# Challenge 5: Sum Free Subsets

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