I remember reading Knuth's paper, and certainly heard DeRemer's name, but it didn't affect much of what I did. There was a paper out of Stanford about that time that influenced me greatly -- it was about pattern matching languages, and proposed separating two ideas: 1. "Here are the patterns that match this tree". And 2. "If more than one pattern matches, here's how to decide which one to use." Given the constraints of size on the PDP 11, anything but LR(1) was infeasable. But using ambiguous grammars and broadening the shift/reduce test to trest operator precedence fit right into that pattern. Another thing that I think was unique to Yacc at the time was introducing symbols that matched the empty string whose reduction caused program actions. Many similar parser systems at the time could not deal with these "empty" symbols.