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 (Colmerauer
& Roussel, 1970), is a highly recommended account of the circumstances that led
to the development of Prolog. Bob Kowalski (1988) presents his views of the early
history of Prolog from the automatic theorem proving perspective. Finally, my own
paper on the topic (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.