Untangling the BlockDAG

on YouTube ↗55m

" summary

Compares specific block DAG designs (GHOST, inclusive/FruitChain, parallel-chain, SPECTRE, Phantom) and presents Spacemesh as a built layered-DAG consensus: blocks tied to proofs-of-spacetime, fixed layered mesh timing, blocks point to preceding layers, and ordering is by layer then ID. Consensus uses per-block votes on validity plus a weak common coin to break balancing attacks, aiming for race-free incentives and a self-healing mode; requires stronger honest-majority assumptions than Nakamoto but removes Poisson lotteries and shows practical implementability.

AI-written summary · about

" chapters (17)

1. 0:00Intro
2. 2:07Ledger Requirements
3. 5:22Challenges for Ledger Consensus
4. 7:52Consensus is Hard
5. 11:23Nakamoto's Magic Trick
6. 13:12Generalized Blockchain (Nakamoto Style)
7. 14:51Ledger Topology
8. 19:35What's Wrong With Chains?
9. 23:19DAG to the Rescue?
10. 24:41(Partial) Directory of BlockDAGS
11. 25:45GHOST
12. 27:15Inclusive Blockchains / FruitChain
13. 33:52SPECTRE
14. 37:44PHANTOM
15. 39:55Robust to failures
16. 43:04Race-Free
17. 45:04Spacemesh Consensus

" related talks

• 47mCant we just agreeVojtěch Juránek, Ondra Chaloupka · DevConf.CZ 2019
• 22mOptimizing network topologies...Wyatt Meldman Floch, Ryle Goehausen · Scale By The Bay 2018
• 42mBeyond Blockchain: Convergent ConsensusMike Anderson · Strange Loop 2022
• 20mShared Security in the BLOCKCHAINIsmail Khoffi · Cosmoverse 2021
• 43mAll Together Now: An Introduction to Distributed ConsensusTess Rinearson · Craft Conference 2019
• 52mBinding Blockchains Together with AccountabilityFrançois René Rideau · LambdaConf 2018
• 19mLiDO-DAG: A Framework for Verifying Safety and Liveness of DAG-Based Consensus ProtocolsLongfei Qiu, Ji-Yong Shin, Zhong Shao, Jingqi Xiao · PLDI 2025
• 13mMulti-chain governance: How can DAOs live across chainsChris Powers · The DAOist #2 Lisbon 2021