Aho received a B.A.Sc. (1963) in Engineering Physics from the
University of Toronto, then an M.A. (1965) and Ph.D. (1967) in Electrical Engineering/Computer Science from
Princeton University. He conducted research at
Bell Labs from 1967 to 1991, and again from 1997 to 2002 as Vice President of the Computing Sciences Research Center. Since 1995, he has held the Lawrence Gussman Professorship in
Computer Science at
Columbia University. He served as chair of the department from 1995 to 1997, and again in the spring of 2003. In his PhD thesis Aho created
indexed grammars and the
nested-stack automaton as vehicles for extending the power of
context-free languages, but retaining many of their decidability and closure properties. One application of indexed grammars is modelling parallel rewriting systems, particularly in biological applications. 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. The fgrep algorithm has become known as the
Aho–Corasick algorithm; it is used by several bibliographic search-systems, including the one developed by Margaret J. Corasick, and by other string-searching applications. At Bell Labs, Aho worked closely with
Steve Johnson and
Jeffrey Ullman to develop efficient algorithms for analyzing and translating programming languages. Steve Johnson used the bottom-up LALR parsing algorithms to create the syntax-analyzer generator
yacc, and
Michael E. Lesk and
Eric Schmidt used Aho's regular-expression pattern-matching algorithms to create the lexical-analyzer generator
lex. The lex and yacc tools and their derivatives have been used to develop the front ends of many of today's programming language compilers. Aho and Ullman wrote a series of textbooks on compiling techniques that codified the theory relevant to compiler design. Their 1977 textbook
Principles of Compiler Design had a green dragon on the front cover and became known as "the green dragon book". In 1986 Aho and Ullman were joined by
Ravi Sethi to create a new edition, "the red dragon book" (which was briefly shown in the 1995 movie
Hackers), and in 2006 also by
Monica Lam to create "the
purple dragon book". The dragon books are used for university courses as well as industry references. In 1974, Aho,
John Hopcroft, and Ullman wrote
The Design and Analysis of Computer Algorithms, codifying some of their early research on algorithms. This book became one of the most highly cited books in computer science for several decades and helped to stimulate the creation of algorithms and
data structures as a central course in the computer science curriculum. Aho is also widely known for his co-authorship of the
AWK programming language with
Peter J. Weinberger and
Brian Kernighan (the "A" stands for "Aho"). Aho's research interests include programming languages, compilers, algorithms, and
quantum computing. He is part of the Language and Compilers research-group at Columbia University. Overall, his works have been cited 81,040 times and he has an
h-index of 66, as of May 8, 2019. Aho has received many prestigious honors, including the
IEEE's
John von Neumann Medal and membership in the
National Academy of Engineering and the
National Academy of Sciences. He was elected a Fellow of the
American Academy of Arts and Sciences in 2003. He holds honorary doctorates from the
University of Waterloo, from the
University of Helsinki, He is a Fellow of the
American Association for the Advancement of Science,
ACM,
Bell Labs, and
IEEE. Aho, Hopcroft, and Ullman were co-recipients of the 2017
C&C Prize awarded by
NEC Corporation. He and Ullman were named recipients of the 2020
Turing Award on March 31, 2021. ==Personal life==