Rarely do research paths diverge and converge as neatly and productively
as the paths exemplified by the two efforts contained in this book. The
story behind these researches is worth recounting. The story, as far as
I'm concerned, starts back in the Fall of1976, when John Laird and Paul
Rosenbloom, as new graduate students in computer science at
Carnegie-Mellon University, joined the Instructible Production System
(IPS) project (Rychener, Forgy, Langley, McDermott, Newell, Ramakrishna,
1977; Rychener & Newell, 1978). In those days, production systems were
either small or special or both (Newell, 1973; Shortliffe, 1976). Mike
Rychener had just completed his thesis (Rychener, 1976), showing how
production systems could effectively and perspicuously program the full
array of artificial intelligence (AI) systems, by creating versions of
Studellt (done in an earlier study, Rychener 1975), EPAM, GPS,
King-Pawn-King endgames, a toy-blocks problem solver, and a
natural-language input system that connected to the blocks-world system.