19-10-2018: Advise-Me workshop on digital assessment in mathematics.
8-6-2018: Our research paper Fine-grained Cognitive Assessment based on Free-form Input for Math Story Problems was accepted for EC-TEL 2018.
25-5-2018: ideas-1.7 is released.
30-9-2016: Kick-off meeting for the Advise-Me Erasmus+ project.
5-2-2016: Our journal article about the Ask-Elle tutor has been published in Journal of AIED.


Selected publications

Or visit the full list of publications.


Advise-Me In the Advise-Me project we develop an approach to using ICT for assessing mathematics achievement of pupils using learning environments for mathematics. In particular, we look at fine-grained cognitive assessment of free-form answers to math story problems, which requires determining the steps a pupil takes towards a solution, together with the high-level solution approach used by the pupil. We recognise steps and solution approaches in free-form answers and use this information to update a user model of mathematical competencies. We use the user model to find out for which student competencies we need more evidence of mastery, and determine which next problem to offer to a pupil. We have tested our work on a large dataset for one problem, and have performed multiple pilot studies in different European countries.

Ideas At the Open University in the Netherlands, we have started the Ideas project (Intelligent Domain-specific Exercise Assistants), which aims at developing tools for incrementally solving exercises. Our research focus is on strategies for exercises, which guide the reasoning in a particular domain. The software is written in Haskell and can be found on Hackage.

The Helium Compiler I am also interested in improving the quality of type error messages for higher-order, functional programming languages (such as Haskell). For this purpose, we have designed the TOP framework for constraint-based type inference, which is used in the Helium Compiler. A detailed description of this framework is given in my PhD thesis.

PhD supervision

Supervised Master's theses


In addition to supervising Bachelor and Master projects, I teach the following courses at the Open University:
Functioneel programmeren
Design patterns
Software architecture
Software evolution
Research preparation


My office is in the BBG building at De Uithof, Utrecht. Click here for a detailed description how to reach my office, or see my former staff page for further contact information.
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