Bitcoin: A Complex Adaptive System Composed of Three Formal Systems For a long time, Bitcoin has been seen simply as a cryptocurrency or a decentralized ledger based on blockchain technology. However, upon closer analysis of its architecture, we can find that Bitcoin is not a single blockchain technology, but a complex adaptive system composed of three different but collaborative formal systems. Understanding this essence helps us better understand the uniqueness of Bitcoin and reflect on the design choices of other cryptocurrencies. The core of Bitcoin consists of three formal systems: 1. Ownership of 1:1 mapping between UTXO ledger state bound with key and human individual (distributed human-computer interaction formal system): The value and ownership of Bitcoin exist in the form of Unspent Transaction Output (UTXO). Each UTXO is a specific amount of Bitcoin and is bound to one or more public keys (addresses). The ownership of these public keys is held by individuals who possess the corresponding private keys, forming a 1:1 mapping relationship between UTXO and human individuals. This formal system of human-computer interaction is distributed, where each user's wallet stores information about their UTXO and authorizes transactions through private key signatures, achieving peer-to-peer value transfer. UTXO itself can be seen as a miniature formal system of human-computer interaction, recording the transfer of value and the change of ownership. The entire UTXO ledger state exists in a distributed form in the wallets of network participants. 2. A transaction collection time series system composed of Block and Chain data structures (centralized blockchain verification structure): In contrast to the distributed UTXO system, the blockchain of Bitcoin is a centralized overall structure. It is composed of blocks containing transaction records linked in chronological order. The core function of this blockchain is to verify the validity of transactions, and the key to verification is to check whether the signature of the UTXO in the transaction matches the individual who owns the UTXO private key. Therefore, blockchain confirms the ownership transfer of the distributed human-computer interaction formal system by verifying the UTXO signature in the transaction. In addition, blockchain also undertakes the function of verifying the proof of work results of distributed miners. Each new block contains a Nonce found by miners through competitive computation that meets the difficulty requirements, and the entire network can verify the validity of this Nonce through simple hash calculations. Therefore, the unified and replicable overall structure of blockchain serves both to verify the ownership of distributed UTXO systems and to verify the correctness of distributed mining processes. 3. Distributed NP solving formal systems (Miners): The security of the Bitcoin network relies on a distributed NP solving system, namely miners. These miners are independent agents that perform extensive hash calculations by consuming resources such as electricity, competing to find Nonce values that meet the current difficulty target. The process of searching for Nonce is essentially an NP solving problem, which is difficult to quickly find the answer, but once found, verification is very simple. When a miner successfully finds Nonce and packages it into a new block, it will be broadcasted to the entire network, verified by other nodes, and added to the longest chain. Through this distributed competition and longest chain consensus mechanism, Bitcoin achieves the security of its ledger without the need for centralized institutions. The distributed nature of miners means that there is no single control point, while the proof of work mechanism effectively prevents malicious attacks. The complex adaptability of Bitcoin: The brilliance of Bitcoin lies in the synergy between these three formal systems. The distributed UTXO system gives users direct control over their assets and the ability to conduct peer-to-peer transactions, giving rise to the value of electronic currency. Centralized blockchain provides a unified and trusted platform for verifying these distributed transactions and maintaining the overall state of the system. The distributed miner system provides guarantees for the continuous updates and security of the blockchain through its NP solving process. Each block in the blockchain is a consensus result generated by distributed miners through non-linear emergence, which is an important source of Bitcoin security. Misunderstandings and structural issues of Ethereum: Unlike Bitcoin, which has a ternary structure, some cryptocurrencies such as Ethereum tend to unify these three formal systems into a single blockchain structure. For example, Ethereum consolidates distributed account states into a unified world state tree that exists throughout the entire blockchain, rather than being distributed among individual users like Bitcoin's UTXO. Meanwhile, Ethereum's BFT POS consensus mechanism is also directly integrated into the overall structure of the blockchain. The practice of centralizing all functions in a single blockchain formal system leads to issues of "perceived closure" and "structural centralization". Although Ethereum's EVM is powerful, it is inherently closed and cannot directly perceive and process information from the external real world. However, centralizing the account system into the world state tree resulted in ownership of the account system belonging to the smart contract developer, rather than to each individual user. The root of this structural choice lies in a misunderstanding of Bitcoin technology, believing that Bitcoin is merely a non Turing complete blockchain technology. However, as shown in the above analysis, Bitcoin is actually a complex adaptive system ingeniously composed of three different formal systems. Inspiration from GEB project: Understanding the ternary structure of Bitcoin, as well as the choices and potential issues in formal system design of systems such as Ethereum, is crucial for building more advanced and complex adaptive systems. The GEB project has learned from these experiences and lessons, aiming to build a complex adaptive system that can perceive reality. The GEB project will pay more attention to the balance between distributed and centralized systems in the design of formal systems, integrate multiple types of formal systems, and effectively integrate external real-world information into the operation of the system, thereby breaking through the limitations of the existing blockchain technology's "perceptual closure". In short, the unique feature of Bitcoin is that it is not a single blockchain, but a complex adaptive system composed of a distributed human-computer interaction UTXO system, a centralized blockchain verification structure, and a distributed NP solving miner system. This sophisticated architecture design endows Bitcoin with strong vitality and security, and provides valuable insights for us to understand and build future complex adaptive systems.