PhD , Formal methods in Natural Language Processing

PhD Candidate, Formal methods in Natural Language Processing

Leiden University was founded in 1575 and is one of Europe’s leading international research universities.

Applications are invited until: 26 juni 2026

Applications are invited for a fully funded PhD candidature on the use of formal methods to enhance the efficiency, transparency and the understanding of Large Language Models. While large language models (LLMs) have proven successful in many areas of Natural Language Processing, they suffer from high data and resource usage and display limited generalization capacity in tasks that humans excel at.

In this PhD project you will have the opportunity to investigate how formal methods can help in developing more efficient and more transparent models for Natural Language Understanding. The specific project content is to be decided between the applicants’ interest and the expertise of the supervisor (dr. Gijs Wijnholds: (Use the "Apply for this Job" box below).). Topics for the PhD may include (but are not limited to):

• Using logical methods to define task-relevant constraints on LLM fine tuning;
• Combining neural and symbolic approaches to solve Natural Language Understanding tasks;
• Assessing the generalization capacity of LLMs in the context of reasoning tasks and/or model probing;
• Evaluation of Natural Language Understanding models in the presence of ambiguity and/or annotator disagreement;
• Understanding multilingual Natural Language Inference in Vision-Language Models.

In this position you are expected to develop your own research line; as such we ask for a brief research proposal (max. 1 page) which outlines a project you would like to work on. You will be embedded in the Leiden Institute of Advanced Computer Science (LIACS) at Leiden University, supervised by dr. Gijs Wijnholds and prof. dr. Suzan Verberne.

• Conduct original research in the field of Natural Language Understanding, focusing on the combination of formal methods and Large Language Models;
• Publish and present scientific work at international journals and conferences;
• Engage in collaboration with other researchers within and outside LIACS;
• Assist in relevant teaching activities.

• A master’s degree in computer science, Artificial Intelligence, Computational Linguistics, Logic, or a related field;
• Substantial knowledge of Natural Language Processing;
• A strong interest in multidisciplinary approaches combining formal tools with neural models;
• Excellent analytical and problem-solving skills;
• Knowledge of deep learning architectures, specifically Large Language models;
• Excellent writing and presentation skills;
• Excellent programming skills (Python).

• We offer a full-time 1-year term position for initially one year. After a positive evaluation of the progress of the thesis, personal capabilities and compatibility, the appointment will be extended by a further three years. This contract falls under the CLA of Dutch Universities;
• A salary between € 3.059,= and € 3.881,= gross per month, based on a full-time appointment (38 hours) (Payscale P);
• A holiday allowance (8%), an end-of-year bonus (8,3%), and an attractive pension scheme at ABP;
• Full reimbursement of public transport commuting costs for home-to-work travel;
• Flexible working hours: as a standard, you are entitled to a minimum of 29 leave days on the basis of a full-time working week of 38 hours; you can also save for extra leave, for example by working 40 hours a week, and in this way accrue an extra 96 leave hours, or exchange 96 leave hours for a 36-hour week.
• Lots of options when it comes to secondary employment conditions; we can, for example, discuss options for a sabbatical or paid parental leave. Within our terms of employment individual choices model, you can exchange leave days and/or salary for benefits such as an advantageous sports subscription and bicycle scheme;
• If your work allows it, hybrid working is possible within the Netherlands;
• A home-working allowance (day and internet allowance) and attention for good workplaces. The University will also provide you with a laptop.

Diversity and inclusion are core values of Leiden University. Leiden University is committed to becoming an inclusive community which enables all students and staff to feel valued and respected and to develop their full potential. Diversity in experiences and perspectives enriches our teaching and strengthens our research. High quality teaching and research are inclusive.