# Robert Tarjan

Dr. **Robert Endre Tarjan** (born 30 April 1948 in Pomona, California) is a computer scientist, known for his work in the design and analysis of computer algorithms. He is the James S. McDonnell Distinguished University Professor of Computer Science at Princeton University, and is also a member of Hewlett-Packard's Office of Strategy and Technology.^{[1]}

## Education

Robert Tarjan's father was a child psychiatrist specializing in mental retardation, and ran a state hospital.^{[2]} As a kid, Tarjan read a lot of science fiction, and wanted to be an astronomer. He became interested in mathematics after reading Martin Gardner's mathematical games column in Scientific American. He became seriously interested in math in the eighth grade, thanks to a "very stimulating" teacher.

While he was in high school, Tarjan got a job, where he worked IBM card punch collators. He first worked with real computers at a summer science program in 1964.^{[2]}

Tarjan completed B.S. in mathematics from the California Institute of Technology in 1969.^{[1]} He went on to receive an M.S. and Ph.D. in computer science from Stanford University in 1971 and 1972, respectively. His Ph.D. dissertation was *An Efficient Planarity Algorithm*, and his advisor was eminent computer scientist Robert Floyd.^{[3]} Tarjan selected computer science as his area of interest, because he believed that CS was a way of doing mathematics that could have a practical impact.^{[4]}

## Computer science career

Robert Tarjan has been teaching at Princeton University since 1985.^{[4]} He has also held academic positions at Cornell University (1972-73), University of California, Berkeley (1973-1975), Stanford University (1974-1980), and New York University (1981-1985). He has also been a fellow of the NEC Research Institute (1989-1997), a Visiting Scientist at the Massachusetts Institute of Technology (1996).

Dr. Tarjan has vast industrial experience: he has worked at AT&T Bell Labs (1980-1989), InterTrust Technologies (1997-2001), Compaq (2002) and Hewlett Packard (2006-present). He has served on several ACM and IEEE committees, and has also been editor of several reputed journals.

### Algorithms and data structures

Robert Tarjan has designed many efficient algorithms and data structures for solving problems in a wide variety of application areas. He has published more than 170 refereed journal articles and book chapters.

Robert Tarjan is known for his pioneering work on graph theory algorithms and data structures. Some of his well-known algorithms include the *Tarjan's off-line least common ancestors algorithm* (used to compute the lowest common ancestors for pairs of nodes in a tree), and the *Tarjan's strongly connected components algorithm* (used to the strongly connected components of a graph). The Hopcroft-Tarjan planarity algorithm was the first linear-time algorithm for planarity-testing.^{[5]}

Tarjan has also developed important data structures such as the Fibonacci heap (a heap data structure consisting of a forest of trees), and the splay tree (a self-adjusting binary search tree; co-invented by Tarjan and Daniel Sleator).

## Awards

- Nevanlinna Prize in Information Science (1983) - first recipient
- National Academy of Sciences Award for Initiatives in Research (1984)
- Turing Award, ACM (1986)
- Paris Kanellakis Award in Theory and Practice, ACM (1999)
- Blaise Pascal Medal in Mathematics and Computer Science, European Academy of Sciences (2004)

## References

- ↑
^{1.0}^{1.1}HP Fellows: Robert Endre Tarjan. Hewlett-Packard. Retrieved on 2008-01-09. - ↑
^{2.0}^{2.1}Shasha, Dennis Elliott; Lazere, Cathy A. [1995] (1998). “Robert E. Tarjan: In Search of Good Structure”,*Out of Their Minds: The Lives and Discoveries of 15 Great Computer*. ISBN 978-0387979922. OCLC 32240355. - ↑ Robert Endre Tarjan. Mathematics Genealogy Project. Retrieved on 2008-01-09.
- ↑
^{4.0}^{4.1}Robert Endre Tarjan: The art of the algorithm (interview). Hewlett-Packard (September 2004). Retrieved on 2008-01-09. - ↑ Kocay, William; Kreher, Donald L (2005). “Planar Graphs”,
*Graphs, algorithms, and optimization*. ISBN 978-1584883968. OCLC 56319851.