Self-Reproducing Coins as Universal Turing Machine
This provides a novel approach to enabling smart contract functionality in blockchain systems, potentially simplifying implementation and reducing validation time.
The paper demonstrates that Turing-completeness in blockchain systems can be achieved without complex language features like loops, by using recursive calls across transactions and blocks, and constructs a universal Turing machine in the UTXO model with explicit state relations.
Turing-completeness of smart contract languages in blockchain systems is often associated with a variety of language features (such as loops). In opposite, we show that Turing-completeness of a blockchain system can be achieved through unwinding the recursive calls between multiple transactions and blocks instead of using a single one. We prove it by constructing a simple universal Turing machine using a small set of language features in the unspent transaction output (UTXO) model, with explicitly given relations between input and output transaction states. Neither unbounded loops nor possibly infinite validation time are needed in this approach.