A multidimensional cube of numbers reveals its maximum capacity through just two geometric slices.
Additive combinatorics describes the structure of number sets where no two elements can add up to a third element in that same set. Mathematicians long suspected that the most efficient way to pack these sets into a lattice cube was by slicing the cube twice, but they lacked a proof for higher dimensions. This resolution confirms that the limiting density of these sets follows a rigid geometric rule regardless of how many dimensions the cube has. These sum-free sets are more than just puzzles, as they form the basis for error-correcting codes used in digital transmissions. Determining these exact bounds allows engineers to understand the ultimate limits of data packing and signal clarity. This proof finally closes a major chapter in the study of discrete structures and how they scale as they get more complex.
On the largest sum-free subset of the lattice cube
arXiv · 2605.00816
We determine the limiting density of the largest sum-free subset of the lattice cube $\{1,2,\ldots,n\}^d$ for all $d$, thus resolving the natural conjecture that it is constructed by two appropriate hyperplane slices.