Respected AI pioneer and visionary Nils John Nilsson passed away early this morning at age 86.

Born in Saginaw, Michigan, Professor Nilsson was a founding researcher in the field of AI. Renowned computer science professor Andrew Ng expressed his condolences: “RIP to my friend, colleague, and AI visionary Nils Nilsson. Your work on the A* algorithm has improved countless lives (this is how we find the shortest path from A to B). I will always remember your work, but even more importantly your kindness.” Many others in the AI community paid tribute to Professor Nilsson on social media. HERE Technologies Principal Research Engineer James Fowe wrote: “Some of us literally earn daily bread on the A* Algorithm. Thank you Nils Nilsson R.I.P.”

Nilsson was the first Kumagai Professor of Engineering (Emeritus) in Computer Science at Stanford University, and his contributions to search, planning, knowledge representation, and robotics have been long respected and broadly applied. In his twenty-three years with Stanford’s Artificial Intelligence Center Nilsson worked on statistical and neural-network approaches to pattern recognition, co-invented the A* heuristic search algorithm and the STRIPS automatic planning system, and co-directed work on the integrated mobile robot, SHAKEY.

From 1985 to 1990, Professor Nilsson was Chairman of the Department of Computer Science at Stanford, where he taught artificial intelligence and machine learning while researching how robots can react to the dynamic world, plan actions accordingly, and learn from experience.

Nilsson also published five AI textbooks: Problem-Solving Methods in Artificial Intelligence (1971), Principles of Artificial Intelligence (1980), Artificial Intelligence: A New Synthesis (1998), The Quest for Artificial Intelligence: A History of Ideas and Achievements (2010), and Understanding Beliefs (2014), which was translated into Chinese and has been widely read by researchers in that country.

In The Quest for Artificial Intelligence: A History of Ideas and Achievements, Professor Nilsson wrote, “Artificial intelligence (AI) may lack an agreed-upon definition… For me, artificial intelligence is that activity devoted to making machines intelligent, and intelligence is that quality that enables an entity to function appropriately and with foresight in its environment.”

Professor Nilsson’s work has been praised worldwide and his important contributions will be remembered across many fields.