In combinatorics, the Cameron–Erdős conjecture (now a theorem) is the statement that the number of sum-free sets contained in
The sum of two odd numbers is even, so a set of odd numbers is always sum-free.
subsets of odd numbers in [N ].
The Cameron–Erdős conjecture says that this counts a constant proportion of the sum-free sets.
The conjecture was stated by Peter Cameron and Paul Erdős in 1988.
[1] It was proved by Ben Green[2] and independently by Alexander Sapozhenko[3][4] in 2003.