His work initially focused on modal logic and knowledge representation , but since the early years of the 21st century he has worked mainly in information retrieval .
Maarten de Rijke ( born 1 August 1961 ) is a Dutch computer scientist .
Maarten de Rijke 's work initially focused on modal logic and knowledge representation , but since the early years of the 21st century he has worked mainly in information retrieval .
Maarten de Rijke ( born 1 August 1961 ) is a Dutch computer scientist .