The Laureates

Copyright © Klaus Tschira Stiftung / Peter Badge

Barbara Liskov

Born 7 November 1939, Los Angeles, California, USA

ACM A.Μ. Turing Award (2008) “for contributions to practical and theoretical foundations of programming language and system design, especially related to data abstraction, fault tolerance, and distributed computing.”

Barbara Liskov, nee Barbara Jane Huberman, grew up in San Francisco, where her father was an attorney and her mother was a homemaker. She earned her BA in mathematics at the University of California, Berkeley in 1961. Rather than go directly to graduate school, she took a job as a programmer at the Mitre Corportation, an organization that does computer science research primarily for the US defense department. At Mitre she learned that she was a natural at computer programming. After a year at Mitre, she moved to Harvard to work as a programmer on a project concerned with computer translation of human languages.

Returning to California to do graduate work in computer science at Stanford, she was given financial support in John McCarthy’s lab partly because her earlier work on natural language translation was in the general area of artificial intelligence. In 1968 she became one of the first women in the United States to be awarded a computer science PhD. Her thesis on chess end-games was supervised by John McCarthy.

After receiving her PhD, Liskov moved back to the Boston area to do research at Mitre on software systems. Using an Interdata 3 computer that had the ability to change the instruction set via microcode, she created the “Venus Machine” tailored to support the construction of complex concurrent software, and then used it to implement the Venus operating system, a small timesharing system that supported 16 concurrent users, to explore how well the architecture worked in practice.

In 1971, shortly after finishing her experiments with Venus and presenting a conference paper on the topic, Liskov was urged by another attendee to consider a position at MIT. She left Mitre and joined the MIT faculty as an assistant professor in the Electrical Engineering and Computer Science department. Shortly after arriving at MIT, in joint work with Steve Zilles that built on her experience with Venus at Mitre, she invented the notion of data abstraction as a way to create more reliable software systems.

At MIT she led the design and implementation of the CLU programming language, which emphasized the notions of modular programming, data abstraction, and polymorphism. These concepts are a foundation of object-oriented programming used in modern programming langauges such as Java and C#. Later she invented a new notion of subtyping, known as the Liskov Substitution Principle, and formalized this concept in joint work with Jeannette Wing.

Liskov’s subsequent work has been mainly in the area of distributed systems, which run on computers connected by a network such as the Internet. Her MIT group also created the Argus language, which extended the ideas of CLU to ease implementation of programs distributed over a network; an example is a network-based banking system. Her research addressed many topics, including object-oriented database systems, garbage collection, and security. Of particular significance is her work on replication protocols, which allow a group of machines to provide highly reliable and available service in spite of failures of group members. In the 1980s, in joint work with Brian Oki, she developed “viewstamped replication”, a protocol that allows the group to survive crashes of group members. In the 1990s, in joint work with Miguel Castro, she developed the first efficient protocol to enable group survival even when failed machines misbehave in arbitrary ways (these are the so-called “Byzantine failures”).

Liskov is currently an Institute Professor at MIT, the highest honor awarded to an MIT faculty member. She has received many accolades for her scientific achievements. In 1996 she received the Achievement Award from the Society of Women Engineers, and in 2003 she was listed in Discovery Magazine’s 50 most important women in science. In 2004 she received the IEEE John von Neumann Medal. In 2007 she was awarded the ACM Programming Languages Lifetime Achievement Award. She is a fellow of the ACM, and a member of the National Academy of Engineering, the National Academy of Sciences, and the American Academy of the Arts and Sciences.

Liskov is married to Nathan Liskov. They have a son, Moses, who also has a PhD in Computer Science. Her hobbies include reading, gardening, and bird watching.