Barbara Liskov

Barbara Huberman was born November 7, 1939, in Los Angeles, the eldest of four children. At Berkeley in the late 1950s she was one of only two women majoring in mathematics in her class, and after graduating in 1961 she took a job as an applications programmer at the MITRE Corporation, where she discovered she was good at it. Princeton's graduate mathematics department turned down her application that year with a form postcard explaining that it did not accept female students. She went to Stanford instead, working on a chess-endgame program under the artificial-intelligence pioneer John McCarthy, and in March 1968 became one of the first women in the United States to earn a doctorate in computer science.

At MIT from the early 1970s she built CLU, a programming language that introduced data abstraction, the idea that a program should hide how a piece of data is stored and expose only what can be done with it, a discipline nearly every modern language now takes for granted. In the 1980s she led Argus, one of the first languages built to handle programs distributed across multiple machines. In 1987, working with Jeannette Wing, she formulated what became known as the Liskov substitution principle, a rule for when one type of object can safely stand in for another that is now taught in introductory computer science courses worldwide. She has since worked on Byzantine fault tolerance, the problem of keeping distributed systems reliable even when some of their components fail or lie.

When MIT hired her in 1972 as the first woman on its computer science faculty, the resistance she met there was rarely stated outright. Guests at faculty gatherings would greet her husband, an electrical engineer, with congratulations meant for her; students mistook her for a secretary; she has said she faced a certain amount of testing in her own classroom that a male professor teaching the same material would not have. She has also said she never encountered much deliberate prejudice, only assumptions built into the room before she walked into it, the same assumptions that had already cost her a place at Princeton's graduate school a decade earlier over nothing but her sex.

She remains an MIT Institute Professor, and in 2008 became only the second woman to win the Turing Award, computing's equivalent of a Nobel, cited for her contributions to programming language and system design. The principle bearing her name is now standard material in undergraduate courses that rarely mention the woman who wrote it into a 1987 conference paper. Her son, Moses, earned his own MIT doctorate in computer science in 2004 and now teaches the subject at William & Mary. Outside the lab she has kept to gardening and mystery novels, a private life that, by her own account, changed very little once the recognition finally arrived.

Barbara Liskov's life against the full span of the corpus — the fading end marks a life still in progress.

• CLU programming language invention
  Introduced data abstraction as a formal discipline in language design 1974
• The Liskov substitution principle discovery
  Formulated with Jeannette Wing; foundational to object-oriented programming 1987
• Argus programming language invention
  One of the first languages built for distributed, fault-tolerant computing 1988
• Program Development in Java book
  Textbook co-written with John Guttag on abstraction and object-oriented design 2000

• 1957 aged ~18 Enters UC Berkeley as one of two women majoring in mathematics
• 1961 aged ~22 Graduates Berkeley and takes a programming job at the MITRE Corporation
• 1961 aged ~22 Princeton's graduate mathematics program rejects her application by form postcard, citing her sex
• March 1968 aged 28 Earns a Stanford PhD in computer science, among the first American women to do so
• 1972 aged ~33 Joins MIT as the first woman on its computer science faculty
• 1974 aged ~35 Completes CLU, introducing data abstraction to programming language design
• 1987 aged ~48 Formulates the Liskov substitution principle with Jeannette Wing
• 2004 aged ~65 Her son, Moses Liskov, earns his own MIT computer science doctorate
• 2008 aged ~69 Wins the A.M. Turing Award, computing's highest honor

• John McCarthy 1927–2011
  Coined the term artificial intelligence and created the Lisp programming language. mentor
• Grace Hopper 1906–1992
  Computer scientist and Navy rear admiral who helped develop early programming languages and computing. predecessor