David L. Waltz died on March 22, 2012 after suffering from brain cancer.

Dave was a good friend to Natural Language Engineering, and provided some sage advice when Roberto Garigliano and I started working on the proposed journal in the early 1990s; he subsequently agreed to serve as a founding editorial board member.

David Waltz will be remembered for his exceptionally broad contribution to Computing in general and Artificial Intelligence in particular.

His PhD at MIT in the 1970s was on the use of the Waltz line constraint propagation algorithm in Computer Vision, and it was in this connection that I was first introduced to his work by Jim Doran and Patrick J. Hayes, who used his thesis research in the teaching material for their undergraduate AI courses.

He then moved on to the first of the two main periods in which he worked on natural language processing, undertaking some early and highly influential work on natural language question answering from structured databases, as well as (for its day) massively parallel parsing. During this period he began to work on what is now called Case-Based Reasoning, originating the memory-based learning sub-field.

In the late 1980s Dave worked on massively parallel information indexing and retrieval. His work was very influential on early web search engines like Gopher and Archie when these appeared in the early 1990s. He also did important work on protein analysis, the theoretical and practical limitations of Artificial Intelligence, and, more recently, applications of machine learning and data mining to areas including medicine and power distribution. Very recent work included the use of crowd sourcing to improve metadata generation for OCR'd historic documents.

At various times Dave held faculty positions at the Universities of Illinois, Brandeis, and most recently Columbia. He had also been president of the NEC Research Institute at Princeton and held senior positions at the Thinking Machines Corporation. Honours included fellowships of the AAAI and the ACM, and the AAAI Distinguished Service Award.

In addition, Dave gave his time freely to many boards and advisory panels in Europe as well as the United States.

He was a respected and well-liked colleague who will missed by many.

(Thanks to Yorick Wilks and Kathy McKeown for suggesting revisions to an earlier draft.)