> For the complete documentation index, see [llms.txt](https://polarischain-1.gitbook.io/polarischain/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://polarischain-1.gitbook.io/polarischain/3.-cryptographic-foundations/3.1-overview-and-bft-guarantees.md).

# 3.1 - Overview & BFT Guarantees

Polarischain’s consensus layer is powered by the Mysticeti engine, a DAG-based Byzantine Fault Tolerant (BFT) protocol engineered for institutional-grade finality and throughput. The protocol achieves deterministic consensus in exactly **three communication rounds**—the theoretical minimum for any BFT system—while guaranteeing both **safety** (no conflicting state commitments) and **liveness** (continuous network progress) as long as fewer than one-third of validators are compromised or offline (`f < n/3`, where `n = 3f + 1`).

#### **3.2 DAG Structure & Parallel Block Production**

Rather than relying on sequential, leader-driven block proposal, Polarischain enables **every active validator to concurrently produce blocks in each consensus round**. These blocks form a Directed Acyclic Graph (DAG), where each new block cryptographically references a quorum of blocks from the preceding round. This creates a densely interconnected, forward-propagating structure that decouples block production from global ordering.Each consensus block contains:

* **Author:** Validator authority index
* **Round:** Consensus round identifier
* **Includes:** Cryptographic references to predecessor blocks
* **Statements:** Transaction batches or implicit vote declarations
* **Signature:** CRYSTALS-Dilithium signature over the block digest

This architecture eliminates single-leader bottlenecks, maximizes hardware utilization, and allows the network to process independent transaction streams in parallel while maintaining a single, globally consistent ledger state.


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