33rd  Top people by Erd%C5%91s number: #2 
Robert Endre Tarjan  

Born 
April 30, 1948 Pomona, California 
Fields  Computer Science 
Institutions  Princeton
University HewlettPackard 
Alma mater  Caltech, Stanford 
Known for  Tarjan's offline least common ancestors algorithm 
Notable awards  Turing Award 
Robert Endre Tarjan (born April 30, 1948) is a renowned American computer scientist. He is the discoverer of several important graph algorithms, including Tarjan's offline least common ancestors algorithm, and coinventor of both splay trees and Fibonacci heaps.
He was born in Pomona, California.
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Robert Tarjan's father was a child psychiatrist specializing in mental retardation, and ran a state hospital.^{[1]} As a child, 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.^{[1]}
Tarjan obtained a Bachelor's degree in mathematics from the California Institute of Technology in 1969. At Stanford University, he received his Master's degree in computer science in 1971 and a Ph.D. in computer science (with a minor in mathematics) in 1972. At Stanford, he was supervised by Robert Floyd and Donald Knuth, both highly prominent computer scientists. His Ph.D. dissertation was An Efficient Planarity Algorithm, and his advisor was eminent computer scientist Robert Floyd.^{[2]} 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.^{[3]}
Tarjan has been teaching at Princeton University since 1985.^{[3]} He has also held academic positions at Cornell University (197273), University of California, Berkeley (19731975), Stanford University (19741980), and New York University (19811985). He has also been a fellow of the NEC Research Institute (19891997), a Visiting Scientist at the Massachusetts Institute of Technology (1996).
Tarjan has vast industrial experience: he has worked at AT&T Bell Labs (19801989), InterTrust Technologies (19972001), Compaq (2002) and Hewlett Packard (2006present). He has served on several ACM and IEEE committees, and has also been editor of several reputed journals.
Tarjan has designed many efficient algorithms and data structures for solving problems in a wide variety of application areas. He has published more than 228 refereed journal articles and book chapters.
Tarjan is known for his pioneering work on graph theory algorithms and data structures. Some of his wellknown algorithms include the Tarjan's offline least common ancestors algorithm, and the Tarjan's strongly connected components algorithm. The HopcroftTarjan planarity testing algorithm was the first lineartime algorithm for planaritytesting.^{[4]}
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 selfadjusting binary search tree; coinvented by Tarjan and Daniel Sleator). Another significant contribution was the analysis of the disjointset data structure; he was the first to prove the optimal runtime involving the inverse Ackermann function.
Tarjan is currently the James S. McDonnell Distinguished University Professor of Computer Science at Princeton University, and also works for HewlettPackard.^{[5]}
Tarjan received the Turing Award jointly with John Hopcroft in 1986. The citation for the award states that it was:
For fundamental achievements in the design and analysis of algorithms and data structures.
Tarjan was also elected an ACM Fellow in 1994. The citation for this award [1] states:
For seminal advances in the design and analysis of data structures and algorithms.
Some of the other awards for Tarjan include:


