What is Tree-Graph?

Tree-Graph is the consensus mechanism used by the Conflux Network, which employs a novel DAG (Directed Acyclic Graph) structure combined with a modified GHOST (Greedy Heaviest Observed SubTree) protocol. Unlike traditional blockchains that form a single chain, Tree-Graph allows concurrent block production where multiple blocks can be created simultaneously at the same height. These blocks form a DAG structure, and the GHAST (GHOST-based Heaviest Adaptive SubTree) protocol identifies a pivot chain within the DAG that determines the total ordering of all blocks. Blocks not on the pivot chain are still included as referenced blocks, so their transactions are processed rather than discarded. This approach allows Conflux to utilize all produced blocks, even those that would be orphaned in a traditional blockchain.

Tree-Graph achieves high throughput by processing blocks concurrently — since multiple blocks can be produced and included simultaneously, the network's transaction capacity scales beyond what a single chain can provide. The protocol maintains safety by using the pivot chain to establish a deterministic total ordering of all transactions across all blocks. Confirmation times depend on the block's position relative to the pivot chain, with pivot chain blocks confirming faster than referenced blocks. The protocol is designed to be safe against up to half of the computational power being adversarial (under its proof-of-work variant), or against one-third Byzantine validators in the proof-of-stake variant. The key insight is that the DAG structure captures the inherent parallelism of a distributed network rather than forcing all blocks into a single sequence.

Tree-Graph powers the Conflux Network, which launched its mainnet in October 2020. Conflux was founded by Turing Award winner Andrew Yao's research group at Tsinghua University in Beijing and is one of the few public blockchains with regulatory compliance in China. The project has received backing from the Shanghai government and has been adopted for various applications in China, including a blockchain-based infrastructure for decentralized commerce. Conflux operates with both a proof-of-work component (for block production) and a proof-of-stake component (for finality), creating a hybrid consensus model. The Tree-Graph protocol represents a significant academic contribution to blockchain consensus, demonstrating that DAG-based approaches can achieve both high throughput and deterministic ordering.