Summarizing the breakthrough in MonadBFT Yesterday Category Labs released the MonadBFT paper, describing the consensus mechanism that will power Monad at mainnet. MonadBFT is a significant development in consensus research since it is the first time that Pipelined HotStuff becomes resistant to tail-forking. Tail-forking occurs when a missed slot causes the previous proposal to be discarded and re-mined. It is a severe problem in previous Pipelined HotStuff formulations since it opens up multi-block MEV attacks that destabilize consensus. Alleviating this problem is a huge deal because it gives us all the benefits of Pipelined HotStuff - frequent blocks, low latency, large validator sets - while avoiding the biggest downside. MonadBFT also offers a huge upgrade for finality. It features single-slot (500 ms) speculative finality and two-slot (1s) hard finality. “Speculative finality” means “finality that will revert only in the event of equivocation (double-signing) by a majority of validators”. Equivocation is a major offense in most blockchain systems and is commonly penalized with slashing; the bigger the penalty for equivocation the closer you can think of “speculative finality” to finality. One-slot speculative finality is a huge unlock for high-performance applications, which can confidently display the updated state of the world immediately after the next block is received. These properties make MonadBFT a huge advancement in consensus, and a worthy complement to other compounding improvements in Monad including Asynchronous Execution, Optimistic Parallel Execution, and MonadDb. The rest of this article serves as a summary of how successive improvements in HotStuff have built upon each other, in order to explain the problem that MonadBFT solves. To summarize: 1. HotStuff gives us linear communication complexity so that we can have large validator sets, but it's not very efficient 2. Pipelined HotStuff gives us efficiency and low latency from proposing blocks every slot, but suffers from the problem of tail forks 3. MonadBFT gives us gives us tail-fork resistance and one-slot speculative finality --- HotStuff: Linear communication complexity enables large node counts...