If you solve that for typical hardware (say, SHA-256 at 1µs, network at 100µs per hash), the optimal $b$ hovers around 16–22. The number 19 is the mathematical sweet spot for a specific era of computing (late 2010s, early 2020s). The Matematicka Analiza Merkle 19.pdf is likely a love letter to applied discrete mathematics. It takes a concept that many use as a black box (the blockchain Merkle root) and tears it open to reveal the number theory, probability, and optimization inside.
Where $b$ is the branching factor, $C_{\text{hash}}$ is the cost of hashing one child, and $C_{\text{net}}$ is the cost of transmitting one hash. Matematicka Analiza Merkle 19.pdf
It is the .
Because in cryptography, as in physics, —and the angel is in the analysis. If you solve that for typical hardware (say,
Next time you verify a transaction in a light client, or download a file via BitTorrent, remember: you are standing on the shoulders of a tree with 19 branches, and a mathematician who cared about the 5th decimal of efficiency. It takes a concept that many use as
The analysis might reveal a : For branching factors below 19, the tree is robust; above 19, certain algebraic attacks (using the pigeonhole principle on intermediate nodes) become statistically viable. The Forgotten Lemma: Order Independence One of the most beautiful mathematical properties of a Merkle tree is rarely discussed outside of formal proofs: commutative hashing .