Abstract
Blockchain is a chain-based distributed ledger technology that supports decision systems requiring traceability, automated execution, and cross-organisation coordination with immutability guaranteed through transaction finality. However, in distributed environments characterised by network delays and the absence of global time assumptions, achieving timely and reliable finality remains a fundamental challenge for smart contracts and higher-level decision systems.This thesis investigates finality that extends beyond consensus protocols to affect application correctness and interoperability. Focusing on asynchronous blockchain environments, the research examines the impact of blockchain finality for real-world decision systems.
The first technical contribution addresses unbounded finality delays in asynchronous blockchain protocols. A delay-aware framework, combined with transaction queue management, is introduced for smart contract execution. This approach improves throughput with smart contract execution under variable network conditions.
The second contribution focuses on verifying ledger state consistency when external systems query different nodes in an asynchronous blockchain. Inspired by ensemble learning concepts, a timing-aware state verification framework combining timed automata, byzantine fault-tolerant coordination, and zero-knowledge proofs is proposed to detect and manage state divergence across nodes.
The third contribution addresses cross-chain interaction between asynchronous and partially synchronous protocols. This research focuses on sidechain communication that allows token transfer between chains without changing ownership. A scheduling framework is developed to determine when consensus from one system is sufficiently stable to be transferred across to the other chain.
The results of this thesis demonstrate that achieving finality in asynchronous blockchain systems requires coordination across multiple layers. By introducing frameworks to regulate execution timing, verify ledger state consistency, and manage cross-chain interactions. This research provides practical methods to improve the reliability of blockchain-based decision systems operating under uncertain network conditions.
Thesis is embargoed until 31 July 2028.
| Date of Award | Jul 2026 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Sponsors | Invest Northern Ireland & PricewaterhouseCoopers (PwC) |
| Supervisor | Vishal Sharma (Supervisor) & Karen Rafferty (Supervisor) |
Keywords
- Distributed ledger technology
- blockchain
- smart contracts
- asynchronous blockchain
- blockchain finality
- query management
- cross-chain communication
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