Cameron–Erdős conjecture

The Cameron-Erdős conjecture in the field of combinatorics within mathematics is the statement that the number of sum-free sets contained in $$\{1,\ldots,N\}$$ is $$O\left({2^{N/2}}\right)$$.

The conjecture was stated by Peter Cameron and Paul Erdős in 1988. It was proved by Ben Green in 2003.