Aho, Alfred oral history | 102792704 | Computer History Museum

Description

Alfred Aho was born to a Finnish family in Timmis, Ontario, and moved with his family to Toronto at the age of two. He started at the University of Toronto in 1959, majoring in engineering physics, where he became interested in the modeling of Boolean circuits using Boolean algebra. Aho continued on to a Ph.D. in electrical engineering at Princeton, where he studied under John Hopcroft. At Princeton, Aho met Jeffrey Ullman, with whom he would forge a lifelong collaboration. Aho and Ullman both joined the newly formed Computing Sciences Research Center at Bell Labs upon graduation in 1967. (This is the lab that would produce Unix and C.) Aho and Ullman embarked upon projects related to automata theory, language theory, algorithms, and programming languages, as well as database theory. Aho’s collaborations with Ullman and others at Bell Labs were very productive, producing five books in the first ten years, including The Design and Analysis of Computer Algorithms (1974) with Hopcroft and Ullman. One collaboration, the result of Aho helping a bibliographer, Margaret Corasick, optimize her keyword search program, led to the publication of the Aho-Corasick string search algorithm. A collaboration with Ullman and Steve Johnson led to the creation of the parser generator yacc, using Don Knuth’s LR parsing algorithm.

Aho was also an early adopter of Unix within Bell Labs, using the roff tool to typeset his papers. The combination of yacc and lex, a lexical analyzer generator created by Michael Lesk and optimized by Eric Schmidt, who applied one of Aho’s regular expression pattern matching algorithms to lex, became a quick way to construct the front end of a compiler. Brian Kernighan and Lorinda Cherry used yacc and lex to create EQN, a tool for typesetting mathematical notation, which would be adopted by Knuth in TeX. Ullman and Aho then codified their accumulated ideas and practical experience with parsers and other phases of compilation into the dragon books, the canonical textbooks on compilers, the first of which was published in 1977. The second edition in 1980 added a coauthor, Ravi Sethi, and added more material about the construction of efficient compilers. The third edition was published in 2007.

Aho also created the AWK language with Peter Weinberger and Brian Kernighan, a Unix tool that matches patterns and executes actions in response, that was extremely useful for writing short two-line programs for routine administrative data processing tasks. Aho’s experience in compiler theory and design led to the creation of a 15-week course at Columbia University, where he joined in 1995 as chair of the computer science department. In his course, students created their own original programming languages and compilers, and incorporated software engineering lessons Aho had learned from a stint as an executive at Bellcore (the research arm of the Baby Bells) between leaving Bell Labs and joining Columbia.

One of the students in the course, Krysta Svore, became Aho’s Ph.D. student and created a quantum computing programming language for her thesis, going on to become Microsoft’s VP of quantum computing. Aho’s collaboration with Svore introduced him into the world of quantum computing. In the 2000s, Aho also explored the idea of “computational thinking.” Aho rejoined Bell Labs in 1997 before returning to Columbia in 2002.

Date

2022-06-13

Contributor

Aho, Alfred V., Interviewee

Hsu, Hansen, Interviewer

Publisher

Computer History Museum

Place of Publication

Chatam, NJ

Extent

33 p.

Format

PDF

Subject

University of Toronto; Princeton University; Bell Labs; Columbia University; Bellcore; Automata Theory; algorithm; Compilers (Computer programs); Aho-Corasick algorithm; UNIX; regular expression; LR parsing algorithm; dragon books; qunatum computing; McCluskey, Edward; Hopcroft, John; Ullman, Jeffrey; Corasick, Margaret; McIlroy, Doug; Thompson, Ken; Ritchie, Dennis M., 1941-2011; Johnson, Steve; Knuth, Donald; Schmidt, Eric; Lesk, Michael; Kernighan, Brian; Cherry, Lorinda; Weinberger, Peter; Svore, Krysta; Weller, Adrian; Sloane, Neil; Beeri, Catriel; Codd, Ted

Collection Title

CHM Oral History Collection

Lot Number

2022.0084

Artifact Details

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