Chelsea L. Edmonds

Department of Computer Science

Regent Court

University of Sheffield

Sheffield, UK

Welcome! I’m Chelsea, a postdoctoral Research Associate in Verification at the University of Sheffield. My primary research interests are formalised mathematics, proof assistants (particularly Isabelle/HOL), and formal methods for security and concurrency. In my current position, I’m working on the COVERT project with Dr. Andrei Popescu and Prof. John Derrick (as well as collaborators at Surrey and Kent), which aims to develop verification tools and models for reasoning on the security of programs running on advanced architectures.

Previously, I completed my PhD at the University of Cambridge under the supervision of Prof. Lawrence C. Paulson. My PhD explored how we can develop modular, flexible and extensible libraries for formalised mathematics (particularly combinatorics) in Isabelle/HOL, and the process for mirroring human intuitive proof techniques in a formal environment. I’m grateful to have been fully funded by a Cambridge Australia Scholarship and a studentship from the Department of Computer Science. My PhD work was further acknowledged by a British Federation of Women Graduates Academic Award.

Beyond my research, I’m a passionate educator and an Associate Fellow with AdvanceHE. I’ve been involved in numerous STEM outreach events and organisations, as well as gender diversity initiatives for Women in STEM.

Recent News

Sep 15, 2025	I’ve accepted a continuing position as a Lecturer (equiv. Assistant Professor) at the University of Western Australia, and will be starting in November. Very excited to be moving home to Australia after 6 incredible years in the UK, and thankful to all those who supported me to get here!
Sep 01, 2025	I’m looking forward to being a lecturer at the ANU Logic Summer School in December this year! An abstract for my course is now available on the website, and registration is open.
Jul 15, 2025	I was invited to give a talk on Formalised Mathematics in Isabelle/HOL at Heidelberg University as part of their Research Seminar series on Formal Mathematics. Thank you to Florent Schaffhauser and Judith Ludwig for hosting - exciting to also hear about some of the current work in that group and to continue to see formal maths becoming a central part of mathematics departments!
Feb 18, 2025	I’ll be a lecturer at this years Midlands Graduate School (MGS). Registration is now open. For more information see the MGS website. Information on my course will be provided here.

Selected Publications

ACM
Formal Probabilistic Methods for Combinatorial Structures using the Lovász Local Lemma

Chelsea Edmonds, and Lawrence C. Paulson

In Proceedings of the 13th ACM SIGPLAN International Conference on Certified Programs and Proofs, London, UK, 2024

Distinguished Paper Award Abs DOI Bib HTML

Top 10% of accepted papers

Formalised libraries of combinatorial mathematics have rapidly expanded over the last five years, but few use one of the most important tools: probability. How can often intuitive probabilistic arguments on the existence of combinatorial structures, such as hypergraphs, be translated into a formal text? We present a modular framework using locales in Isabelle/HOL to formalise such probabilistic proofs, including the basic existence method and first formalisation of the Lovász local lemma, a fundamental result in probability. The formalisation focuses on general, reusable formal probabilistic lemmas for combinatorial structures, and highlights several notable gaps in typical intuitive probabilistic reasoning on paper. The applicability of the techniques is demonstrated through the formalisation of several classic lemmas on the existence of hypergraphs with certain colourings.
@inproceedings{10.1145/3636501.3636946, author = {Edmonds, Chelsea and Paulson, Lawrence C.}, title = {Formal Probabilistic Methods for Combinatorial Structures using the Lov\'{a}sz Local Lemma}, year = {2024}, isbn = {9798400704888}, publisher = {Association for Computing Machinery}, address = {New York, NY, USA}, doi = {10.1145/3636501.3636946}, booktitle = {Proceedings of the 13th ACM SIGPLAN International Conference on Certified Programs and Proofs}, pages = {132–146}, numpages = {15}, keywords = {probability, hypergraph colourings, formalisation of mathematics, combinatorics, Lov\'{a}sz local lemma, Isabelle/HOL, Interactive theorem proving}, location = {London, UK}, series = {CPP 2024}, }