Alfred Aho
He and his long-time collaborator Jeffrey Ullman are the recipients of the 2020 Turing Award, generally recognized as the highest distinction in computer science.[8] In his PhD thesis Aho created indexed grammars[9] and the nested-stack automaton[10] as vehicles for extending the power of context-free languages, but retaining many of their decidability and closure properties.[12] After graduating from Princeton, Aho joined the Computing Sciences Research Center at Bell Labs where he devised efficient regular expression and string-pattern matching algorithms that he implemented in the first versions of the Unix tools egrep and fgrep.[13] At Bell Labs, Aho worked closely with Steve Johnson and Jeffrey Ullman to develop efficient algorithms for analyzing and translating programming languages.[16] The lex and yacc tools and their derivatives have been used to develop the front ends of many of today's programming language compilers.