PhD Scholarship in Combinatorial Search & Optimization (Certifying Algorithms / Proof Logging) – Brussels, Belgium

Publié il y a 3 semaines

1 – Working at the VUB

For more than 50 years, the Vrije Universiteit Brussel has stood for freedom, equality and solidarity, and this is very much alive on our campuses among students and staff alike.

At the VUB, you will find a diverse collection of personalities: innovators pur sang, but above all people who are 100% their authentic selves. With some 4,000 employees, we are the largest Dutch-speaking employer, in the private sector, in Brussels; an international city with which we are only too happy to connect and where (around) our 4 campuses are located.

Add to this our principle of free research – in which self-reflection, a critical attitude and an open, creative mind around scientific and social issues are central – and you have a university that is fundamentally groundbreaking and pioneering in education and research. In short: the VUB all over again.

Moreover, the VUB is a member of EUTOPIA, an alliance of like-minded European universities, all ready to reinvent themselves.

2 – Position description

The Faculty of Sciences and Bioengineering Sciences, Department Computer Science, is looking for a PhD-student with a doctoral grant.

More concretely your work package, for the preparation of a doctorate, contains:

We are looking for an excellent researcher to strengthen Bart Bogaerts’ research group on Knowledge Representation and Combinatorial Optimization. This research group is part of the Artificial Intelligence Lab, the oldest AI Lab on the European mainland, situated in Brussels, the heart of Europe.

We are particularly looking for someone who can strenghten the recently-launched research line on proof logging (also known as certifying algorithms) for combinatorial optimization. In this line of research, the goal is to develop methods and algorthims that can guarantee with 100% certainty that the answers produced by a combinatorial optimizer are correct. Recent breakthroughs in this direction have resulted in a distinguished paper award at AAAI 2022 [1] as well as a series of tutorials at major conferences (CP, IJCAI). A (short) online version of this tutorial can be found online [2]. The next iteration of the tutorial will be delivered at AAAI 2024 in Vancouver.

You are expected to contribute to go beyond the state-of-the-art of proof logging. In particular, we are interested in investigating how proof logging can be brought to the world of high-level modelling languages, rather than low-level solver languages. More info can be found in the abstract below.

We offer a fully-funded PhD scholarship position for a year (extendable up to max. 48 months, on condition of the positive evaluation of the PhD activities) with a very competitive scholarship (as of today, the starting amount is above 2500 euros net per month). The position also comes with a travel budget. While this is a research position, all PhD students at our lab are expected to contribute to teaching activities; typically, this is at most one session of two hours of practicals per week.

The starting date is flexible; but preferrably around the summer of 2024.


Project abstract:

The field of combinatorial optimization is concerned with developing generic tools that take a declarative problem description and automatically compute an optimal solution to it. Often, users specify their problem in a high-level, human-understandable formal language. This specification is first translated into a low-level specification a solver understands and subsequently solved. Thanks to tremendous progress in solving technology, we can now solve a wide variety of NP-hard (or worse) problems in practice. Moreover, these tools are increasingly used in real-life applications, including high-value and life-affecting decisions. Therefore, it is of utmost importance that they be completely reliable. The central objective of this proposal is to develop methodologies and tools with which we can guarantee with 100% certainty that the right problem has been solved correctly.

To achieve this ambitious objective, we will build on recent breakthroughs in proof logging, where solvers do not just output an answer, but also a machine-verifiable proof (or certificate) of correctness. However, a major limitation of current techniques is that correctness is not proven relative to the human-understandable specification written by the user, but relative to the low-level translation that the solver receives, meaning that there is no guarantee that the solver is solving the original problem. In this project, we will investigate end-to end guarantees of correctness. When successful, this will have a major impact on the way combinatorial optimization software is developed, evaluated, and used: the proofs produced will enable (1) debugging, since proofs contain detailed information about where bugs occurred, (2) auditability, since proofs can be stored and checked by an independent third party, and even (3) rigorous evaluation of algorithmic improvements.

For this function, our Brussels Humanities, Sciences & Engineering Campus (Elsene) will serve as your home base.

3 – Profile

What do we expect from you?

By the start date, you should have obtained a MSc in computer science, in informatics, in mathematics or similar. 

You are expected to have good programming skills and to master the English language.
You have good problem-solving skills and a passionate interest in logic-based methods in computer science.

  • You have not performed any works in the execution of a mandate as an assistant, paid from operating resources, over a total (cumulated) period of more than 12 months.

The VUB wants to be a reflection of the society where everyone’s talent is valued, regardless of gender, age, religion, skin color, migration background, disability and neurodiversity.

4 – Offer

Are you going to be our new colleague?

You’ll be offered a full-time PhD-scholarship, for 12 months (extendable up to max. 48 months, on condition of the positive evaluation of the PhD activities), with planned starting date 01/09/2024.

You’ll receive a grant linked to one of the scales set by the government.

IMPORTANT: The effective result of the doctorate scholarship is subject to the condition precedent of your enrolment as a doctorate student at the university.

At the VUB, you’re guaranteed an open, involved and diverse workplace where you are offered opportunities to (further) build on your career.

As well as this, you will also enjoy various other benefits:

  • Extensive homeworking options, a telework allowance of 50 euros per month OR an internet fee of 20 euros per month;
  • An open and informal working environment where attention is paid to work-life balance, and exceptional holiday arrangements with 35 days of leave (based on a fulltime contract), closure between Christmas and New Year and 3 extra leave days;
  • Cost-free hospitalisation insurance;
  • Full reimbursement of your home-to-work commute with public transport according to VUB-policy, and/or compensation if you come by bike;
  • A wide selection of meals in our campus restaurants at attractive prices;
  • Excellent and affordable facilities for sport and exercise, a range of discounts via Benefits@Work (in  all kinds of shops, on flights, in petrol stations, amusement parks…) and Ecocheques;
  • Nursery near campus, discount on holiday camps;
  • The space to form your job content and to continuously learn through our VUB learning platforms and training courses;
  • And finally: great colleagues with a healthy drive.

5 – Interested?

Is this the job you’ve been dreaming of?

Then apply, at the latest on 18/01/2024via, and upload the following documents:

  • Curriculum vitae including names and contact data of three references.
  • A brief motivation statement describing why the candidate wants to start a PhD, including a list of research interests.
  • A brief summary of the research done in the light of the Master thesis
  • Diplomas and transcripts for relevant obtained degrees (MSc/BSc).

Do you have questions about the job content? Contact Bart Bogaerts at or on +32 2 629 37 06.

Would you like to know what it’s like to work at the VUB? Go to, and find all there is to know about our campuses, benefits, strategic goals and your future colleagues.

Would you like more information about EUTOPIA? Go to, and read more about the role of the VUB in the development of the EUTOPIA alliance.

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