# Scalable Multi-Chain Coordination via the Hierarchical Longest Chain Rule

**Authors:** Yanni Georghiades, Karl Kreder, Jonathan Downing, Alan Orwick, Sriram Vishwanath  
**arXiv:** [2112.11072](https://arxiv.org/abs/2112.11072)  
**Date:** 2021-12-21  
**Summary page:** https://www.summarizepaper.com/fr/paper/2112.11072v2/

## Abstract

This paper introduces BlockReduce, a Proof-of-Work (PoW) based blockchain system which achieves high transaction throughput through a hierarchy of merged mined blockchains, each operating in parallel on a partition the overall application state. Most notably, the full PoW available within the network is applied to all blockchains in BlockReduce, and cross-blockchain state transitions are enabled seamlessly within the core protocol. This paper shows that, given a hierarchy of blockchains and its associated security model, the protocol scales superlinearly in transaction throughput with the number of blockchains operated by the protocol.