Céline Deknop will present her doctoral thesis on advanced code differencing techniques in the context of automated large-scale refactoring for legacy software systems. The research focuses on enhancing comprehension and trust in these automated processes. The research involves collaborations with Raincode Labs, a company specializing in legacy software and automated refactoring. Several tools and techniques are developed, including a log-based behavioural differencing algorithm, a COBOL semi-parser, and a trace equivalence comparator. These tools are accompanied by visualisation modules, facilitating better communication with clients and reinforcing trust in automated refactoring processes. The contributions of this work have the potential to benefit both Raincode Labs and the wider software engineering community, providing solutions to challenges in legacy software maintenance and refactoring.