Berkeley Yacc owes much to the unflagging efforts of Keith Bostic. His badgering kept me working on it long after I was ready to quit. Berkeley Yacc is based on the excellent algorithm for computing LALR(1) lookaheads developed by Tom Pennello and Frank DeRemer. The algorithm is described in their almost impenetrable article in TOPLAS 4,4. Finally, much of the credit for the latest version must go to those who pointed out deficiencies of my earlier releases. Among the most prolific contributors were Benson I. Margulies Dave Gentzel Antoine Verheijen Peter S. Housel Dale Smith Ozan Yigit John Campbell Bill Sommerfeld Paul Hilfinger Gary Bridgewater Dave Bakken Dan Lanciani Richard Sargent Parag Patel