Ramanujan graphs

Ramanujan graphs are highly efficient networks that connect a set of points (nodes) with very few connections, yet still facilitate rapid communication. They exhibit an optimal balance between sparsity (fewer edges) and robustness (short paths between nodes), making them ideal for network design, coding theory, and cryptography. These graphs are named after mathematician Srinivasa Ramanujan because they possess exceptional mathematical properties related to the distribution of their eigenvalues, which underpin their impressive connectivity and expansion qualities despite having very few links per node.