CS MSc Thesis Presentation 25 August 2026

Tuesday, 25 August there will be a master thesis presentation in Computer Science at Lund University, Faculty of Engineering.

The presentation will take place in E:2116.

Note to potential opponents: Register as an opponent to the presentation of your choice by sending an email to the examiner for that presentation (firstname [dot] lastname [at] cs [dot] lth [dot] se). Do not forget to specify the presentation you register for! Note that the number of opponents may be limited (often to two), so you might be forced to choose another presentation if you register too late. Registrations are individual, just as the oppositions are! More instructions for opponents are found here on the LTH thesis project page.

13:15-14:00 in E:2116

• Presenters: Daniel Adu-Gyan, Dag Hemberg
• Title: DeCypher: Debugging Queries in Graph Databases
• Examiner: Görel Hedin
• Supervisors: Anton Risberg Alaküla (LTH), Oskar Damkjaer (Neo4j)

Debugging tools are useful for software development. Imperative languages often have debuggers that allow developers to execute the code step-by-step, but declarative languages, like database query languages, largely lack equivalent support. Instead, special-purpose debuggers are needed.

In this thesis we present DeCypher, a query-plan-based step-by-step debugger for Neo4j’s declarative query language Cypher, which lets developers perform many debugging tasks similar to ones found in imperative languages.

We evaluate the usefulness and experience of using DeCypher through a user study, comparing debugging performance with and without the tool across four debugging tasks. We show that participants using DeCypher achieve a higher success rate in locating bugs, but no meaningful change in perceived difficulty when doing so.

These findings suggest that step-by-step debugging based on the query plan can help Cypher developers, but is likely not a complete replacement for existing approaches.