Robert Floyd

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Robert "Bob" W Floyd (born June 8, 1936 in New York City , † September 25, 2001 in Stanford , California ) was an American computer scientist and Turing Prize winner . He had his original middle name changed to "W", but he often emphasized that "W." was a valid abbreviation for it.


Floyd was born in New York City in 1936 and recognized as a child prodigy at the age of six. He skipped three school grades and finished school at the age of 14. At the University of Chicago , he received a bachelor's degree in liberal arts thanks to a scholarship in 1953 (when he was 17) and a second bachelor's degree in physics in 1958.

During his studies he became a computer operator and later a programmer at the Illinois Institute of Technology . In 1959 he began to publish several notable articles in computer journals ( Donald E. Knuth : “When I was collecting material for a monograph on parsing in 1966 , I came to the conclusion that only five really good papers on compilers had been written and Bob was the author of all five. ”). In 1962 he became a Senior Project Scientist at Computer Associates .

In 1965 he was appointed associate professor at Carnegie Mellon University and served on the editorial board of the Journal of the ACM . In 1968 he went to Stanford University , where he was given a full professorship in 1970 and headed the computer science faculty from 1973 to 1975. He reached this position without a doctorate. Floyd also spent a year at the Naval Postgraduate School . In 1994 he retired. Floyd's doctoral students include later Turing Prize winners Robert Tarjan and Ronald L. Rivest .

His contributions include efficient algorithms for finding all the shortest paths in a graph ( algorithm by Floyd and Warshall ), for parsing and image processing ( Floyd-Steinberg algorithm ), as well as the discovery of BottomUp heapsort . But perhaps his most important achievement was his pioneering work on program verification using logical assurances in his 1967 article Assigning Meanings to Programs . This was an important contribution that later led to the Hoare calculus .

Floyd worked closely with Donald E. Knuth . He was the main reviewer for Knuth's seminal book The Art of Computer Programming , and he is the one most cited in that work.

Floyd received the Turing Award in 1978 for his influence on the methods of creating efficient and reliable software and for his contribution to the establishment of the following fields of computer science: theory of parsing, semantics of programming languages, automatic program verification, automatic program synthesis and analysis of algorithms. In addition, he received the IEEE Computer Pioneer Award in 1991 and is a Fellow of the American Academy of Arts and Sciences , the American Association for the Advancement of Science and the ACM .

Floyd was married twice (most recently to computer scientist Christiane Floyd ) and had three sons and a daughter. In 2001 he died of Pick's disease .


  • A descriptive language for symbol manipulation. 1961.
  • Syntactic analysis and operator precedence. 1963.
  • The syntax of programming languages ​​- A survey. 1964.
  • Assigning Meaning to Programs. (PDF; 668 kB) In: Jacob T. Schwartz (Ed.): Proceedings of Symposium on Applied Mathematics. Vol. 19. American Mathematical Society , 1967, pp. 19-32.
  • with Richard Beigel: The language of machines. Computer Science Press, 1994 (German The Language of Machines. International Thomson Publishing, Bonn, 1996, ISBN 3-8266-0216-1 ).


  • Donald E. Knuth : Robert W. Floyd, In Memoriam. In: SIGACT News. 34, 4, 2003, pp. 3-13. Reprinted in: IEEE Annals of the History of Computing. 26, 2004.

Web links


  1. ^ Donald E. Knuth: Robert W. Floyd, In Memoriam
  2. Donald E. Knuth: Memorial Resolution Robert W. Floyd (1936–2001) ( online ( Memento of July 3, 2010 in the Internet Archive ); PDF; 12 kB)