*By Engineering Communications* [1]

**The Association for Computing Machinery named Princeton graduate alumni Alfred Aho and Jeffrey Ullman recipients of the 2020 ACM A.M. Turing Award. The award, often referred to as the “Nobel Prize of Computing,” carries a $1 million prize, with financial support provided by Google, Inc. It is named for Alan M. Turing, also a Princeton Ph.D. alumnus, who articulated the mathematical foundation and limits of computing.**

**were recognized**[2] for developing the fundamental algorithms and theory underlying programming language implementation and for synthesizing these results and those of others in their highly influential books, which have educated generations of computer scientists. Aho is the Lawrence Gussman Professor Emeritus of Computer Science at Columbia University. Ullman is the Stanford W. Ascherman Professor Emeritus of Computer Science at Stanford University. Ullman received his doctorate in electrical engineering from Princeton in 1966 and served as a member of the Princeton faculty from 1969 to 1979. Aho received his doctorate in 1967 in electrical engineering from Princeton.

Computer software powers almost every piece of technology with which we interact. Virtually every program running our world – from those on our phones or in our cars to programs running on giant server farms inside big web companies – is written by humans in a higher-level programming language and then compiled into lower-level code for execution. Much of the technology for doing this translation for modern programming languages owes its beginnings to Aho and Ullman.

Beginning with their collaboration at Bell Labs in 1967 and continuing for several decades, Aho and Ullman have shaped the foundations of programming language theory and implementation, as well as algorithm design and analysis. They made broad and fundamental contributions to the field of programming language compilers through their technical contributions and influential textbooks. Their early joint work in algorithm design and analysis techniques contributed crucial approaches to the theoretical core of computer science that emerged during this period.

After earning their Ph.D. degrees at Princeton, Aho and Ullman joined Bell Labs, where they worked together from 1967 to 1969. During their time at Bell Labs, their early efforts included developing efficient algorithms for analyzing and translating programming languages.

In 1969, Ullman began a career in academia at Princeton, ultimately joining the faculty at Stanford University, while Aho remained at Bell Labs for 30 years before joining the faculty at Columbia University. Despite working at different institutions, Aho and Ullman continued their collaboration for several decades, during which they co-authored books and papers and introduced novel techniques for algorithms, programming languages, compilers and software systems. Among their most influential books are The Design and Analysis of Computer Algorithms (1974), and Principles of Compiler Design (1977).

Besides Turing himself, who **earned his Ph.D. at Princeton** [3] in 1938, **past winners** [4] of the Turing Award include:

- Marvin Minsky (Ph.D. in mathematics in 1954) in 1969
- John McCarthy (Ph.D. in mathematics in 1951) in 1971
- Michael Rabin (Ph.D. in mathematics in 1957 in 1976
- Dana Scott (Ph.D. in mathematics in 1958) in 1976
- Robert Tarjan, Princeton's James S. McDonnell Distinguished University Professor of Computer Science, in 1986
- Richard Stearns (Ph.D. in mathematics in 1963) in 1993
- Andrew Yao, who was Princeton's William and Edna Macaleer Professor of Engineering and Applied Science from 1986-2004, in 2000
- Robert Kahn (Ph.D. in electrical engineering in 1964) in 2004
- Michael Stonebreaker (BSE in electrical engineering in 1965) in 2014

*Adapted from a release from the ACM.*