A Tribute to Alain Colmerauer

As an invited contributor to this Festschrift honoring Alain Colmerauer, I feel compelled to give not only an account of his main research contributions, but also of my perspective on the motivations behind them. I hope that this will provide the reader with a glimpse of how a focused, tenacious, rigorous, and inventive mind like Alain’s picks research problems and proceeds to solve them. The history of Prolog, the language that remains one of Alain’s major accomplishments, is well documented. His paper on the “Birth of Prolog,” co-authored with Philippe Roussel [Alain Colmerauer and Philippe Roussel, 1970], is a highly recommended account of the circumstances that led to the development of Prolog. Bob Kowalski [Robert Kowalski, 1988] presents his views of the early history of Prolog from the automatic theorem proving perspective. Finally, my own paper on the topic [Jacques Cohen, 1988] contains material complementing Alain’s and Bob’s narratives. Instead of recasting already-available historical material, I have opted to present here a more personal account of Alain’s contributions, acknowledging in advance the individual bias inherent in such an accounting of long-past events.