Barbara Liskov

Institute Professor, Massachusetts Institute of Technology

• Born: November 7, 1939
• Place of Birth: Los Angeles, California

Primary Company/Organization: Massachusetts Institute of Technology

Introduction

Barbara Liskov was the first woman to earn a PhD from a computer science department at a US university. She did not allow gender discrimination in mathematics and science to discourage her from pursuing her academic and professional goals. She developed computer languages that are still used in modern software and system applications, and she attributes her success to the assistance of her many graduate students. In her esteemed position as an Institute Professor at the Massachusetts Institute of Technology (MIT), Liskov has hired women in the computer science department and has mentored a new generation of women pursuing careers in science and technology.

Early Life

Barbara Jane Huberman Liskov was born on November 7, 1939, to a lawyer and a homemaker in Los Angeles, California. She was the oldest of four children. While Liskov's parents valued education, they were indifferent toward her love of mathematics and science. While in high school, she took all of the mathematics and science courses that were available but had to keep her interest a secret from her friends. During her youth, mathematics and science were not considered suitable interests for a girl, and she kept a low profile in her classes. Her father suggested that she take a typing course so she could support herself as a secretary, and she took his advice. She discovered that typing was one of the most useful skills she ever learned; the ability to work quickly on QWERTY keyboards would become essential to her work with computers.

Although Liskov's parents expected that she would go to college, they did not expect her to pursue a career. She enrolled at the University of California at Berkeley, originally as a physics major and then switching to mathematics. Liskov remembers being only one of two women in her classes, and she was too intimidated to say anything in class. She received her bachelor's degree in mathematics in 1961. She applied to graduate mathematics programs at Berkeley and Princeton. Princeton returned her application with a letter informing her that the institution did not accept women. Berkeley accepted her, but she had tired of taking classes and decided to look for a job as a mathematician. She was also eager to live elsewhere in the United States, and decided to move to Boston, her father's home town.

Life's Work

Although Liskov did not find a satisfying job as a mathematician, she accepted a position as a computer programmer at the Mitre Corporation. At Mitre, she discovered her aptitude for computers and programming and decided to pursue a career as a computer scientist. While she found the work rewarding, she had witnessed cases of gender discrimination at the company. She stayed at Mitre for a year, then took on a difficult programming project at Harvard, where she was expected to translate natural language. The project made her realize that she needed to go back to school to learn the fundamentals of programming. She reapplied to the mathematics program at the University of California at Berkeley, as well as the computer science programs at Harvard and Stanford. She was admitted to both Harvard and Stanford and chose Stanford because she wanted to return to California.

During her first semester at Stanford, Liskov met former mathematician and MIT professor John McCarthy. McCarthy had worked with cognitive scientist Marvin Minsky to establish the field of artificial intelligence (AI). Because Liskov received no financial support from Stanford, she asked McCarthy if he would provide funding for her doctoral studies. After McCarthy heard about her work at Harvard on language translation, he said yes. There were so few people in general doing this work that Liskov's experience made her an expert in McCarthy's eyes. Under McCarthy's mentorship, she published her dissertation on chess and games, a work that is still cited. By the time that she graduated in 1968, Stanford had formed a computer science department; she became the first woman in the United States to receive a doctorate from an official computer science department.

After graduation, Liskov returned to Boston to look for work. During her second trip to Boston, she met MIT electrical engineering graduate Nate Liskov; in 1970, they were married. Gender discrimination in employment was still rampant; she ended up returning to Mitre for a staff research position. There she designed computer architecture and implemented it using microcode. She also invented Venus, a new operating system, which she designed and deployed to make better use of the computer architecture. She wrote a paper describing Venus and presented it at the Symposium on Operating System Principles, where it won an award for best paper. MIT faculty member Jerry Saltzer, chair of the session where she had made her presentation, was impressed by her work and urged her to apply for a faculty position at MIT. At the time there were very few women on the MIT faculty, and the university president was strongly encouraging departments to hire more women. Liskov was hired to work in the Computer Science Department in 1972; she was MIT's first female faculty member in computer science. Because female MIT faculty were so rare, MIT faculty often introduced themselves to Liskov's husband, Nathan, at social events, believing that he was the new faculty member.

Liskov had a challenging first year at MIT. Although she had the practical experience from Mitre to teach a computer architecture course, the curriculum covered a great deal of electrical engineering, which she had to learn for the first time. She also began thinking of how to improve the organization and structure of computer programs. Software programmers need to divide their code into smaller pieces, called modules, that could conduct some independent reasoning. Just a year after the microprocessor was invented, Liskov thought of and tested a way to modularize software code. This method, called data abstraction, appears in all major contemporary programming languages. It makes the programs reliable, secure, and easy to use. Liskov did much of her initial work on data abstraction with Steve Zilles, her first graduate student. By her second year at MIT, she had attracted a few other students to her research group. They began to work on CLU, a programming language designed to support use of data abstraction in computer programs. Every major programming language since 1975 has borrowed concepts from CLU.

In the 1980s, Liskov started working on distributed computing: computing carried out by many computers connected by a communications network. She developed a programming language called Argus that allowed a programmer to write distributed applications for networked computers. She would continue to work on distributed programs for networked computers throughout her career.

Liskov earned tenure and promotion for her work at MIT, serving as associate department head for computer science from 2001 to 2004, again the first woman to hold that position. Under her supervision, the computer science department added five female faculty members. She has also run the MIT computer science graduate admissions committee, working hard at increasing the number of women accepted into the doctoral program.

In 1996, Liskov received the Society of Women Engineers Achievement Award. In 2002, she was named by Discover magazine as one of the fifty most important women in science. In 2004, she received the John von Neumann Medal from the Institute of Electrical and Electronics Engineers (IEEE), and in 2005 she was awarded the title of ETH Honorary Doctor by the Swiss Federal Institute of Technology Zurich (ETH). In 2008, she was named by MIT as an Institute Professor, the highest honor awarded to an MIT faculty member. In the same year, she earned the Turing Award of the Association for Computing Machinery (ACM), known as the Nobel Prize of computing—the second woman to have received this honor. She also received the ACM SIGPLAN Programming Languages Achievement Award.

Liskov is a member of the National Academy of Engineering, a Fellow of ACM and of the American Academy of Arts and Sciences. She has served on the National Science Foundation's Computer and Information Science (CISE) Advisory Committee, as well as the Computer Science and Telecommunications Board (CTSB) of the National Research Council. She has written three books, including Abstraction and Specification in Program Development (1986) with John Guttag, which has served as a classic textbook on how to write good software. In 2012, she was inducted into the National Inventors Hall of Fame for her innovations in computer programming languages. She received an honorary doctorate from the Universidad Politécnica de Madrid in 2018.

Liskov has continued her work at MIT as Institute Professor and head of the Programming Methodology Group. Her research interests include programming methodology, programming languages and systems, and distributed computing. She has also worked on cloud security, Byzantine-fault-tolerant storage systems, peer-to-peer computing, and support for automatic deployment of software upgrades in large-scale distributed systems.

Personal Life

Liskov is both a people person and a problem solver. She likes making things work and finding practical, elegant solutions to problems. In these endeavors, she enjoys collaborating with others, especially her students. She has also said that developing software is a hobby.

Liskov credits her success in academia to a work-life balance. When she is not at work, she enjoys reading, gardening, cooking, travel, and birdwatching with her husband, Nathan. In 1975, she had a son, Moses, who earned a PhD in computer science from MIT in 2004 and teaches computer science at the College of William and Mary.

Bibliography

Frenkel, K. A. “Liskov's Creative Joy: Barbara Liskov Muses about the Creative Process of Problem Solving, Finding the Perfect Design Point, and Pursuing a Research Path.” Communications—ACM 52.7 (2009): 20–22. Print. Liskov considers what it is that makes her love her work.

Guttag, John V. “Barbara Liskov.” The Electron and the Bit—EECS at MIT: 1902–2002. 2003: n. pag. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. Web. 1 May 2012. A biography of Barbara Liskov by her coauthor of Abstraction and Specification in Program Development. Examines Liskov's attitudes toward academia, work, research, and women in the sciences.

Liskov, Barbara. "The Architect of Modern Algorithms." Interview by Susan D'Agostino. Quanta Magazine, 20 Nov. 2019, www.quantamagazine.org/barbara-liskov-is-the-architect-of-modern-algorithms-20191120/. Accessed 5 Mar. 2024.

Liskov, Barbara. "An Interview with Barbara Liskov." Interview by Stephen Ibaraki. 2008. Web. Association for Computing Machinery. 1 May 2012. Liskov describes her career. The web page includes additional links to Liskov's MIT web page as well as ACM's feature page on Liskov in recognition of her ACM Turing Award.