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Twenty years ago Terry Winograd and Fernando Flores published a
controversial book about system design that doubted artificial
intelligence would ever show signs of true intelligence. The book,
Understanding Computer and Cognitions: A New Foundation for
Design, sent the AI community reeling while giving wings to a new
perspective that emphasized language rather than symbols for
prompting computer action.

Today the Winograd/Flores work is recognized as a
groundbreaking textbook on system design, and the Language-
Action Perspective (LAP) movement it inspired continues to guide
design practices using human communication and human nature at
its core. This month's special section honors the 20th anniversary
of LAP by presenting a group of articles focusing on its practical
contributions and its ever-growing relevance. Every contributor to
this project was asked to reveal something unexpected they
discovered from using LAP and the value that discovery offers
computing professionals. We hope you find their discoveries
insightful.