Alexander Bogomolny

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Alexander Bogomolny (January 4, 1948  – July 7, 2018) was an Israeli American mathematician. He was known for creating and maintaining the mathematically themed educational website Cut-the-Knot for the Mathematical Association of America (MAA) Online.[1] He wrote extensively about arithmetic, probability, algebra, geometry, trigononometry and mathematical games. He was a pioneer in mathematical education on the internet, having started Cut-the-Knot in October 1996.[2]

Education and academic career[edit]

Bogomolny got his master's degree in mathematics from Moscow State University in 1971.[3] From 1971 to 1974 he was a Junior research fellow at the Moscow Institute of Electronics and Mathematics in Moscow. He emigrated to Israel and became a senior programmer at Lake Kinneret Research Laboratory in Tiberias, Israel (1974 – 1977) and a software consultant at Ben Gurion University in Negev, Be’er Sheva, Israel (1976 – 1977). From 1976 to 1983 he was a Senior Instructor and researcher at Hebrew University in Jerusalem. He got his Ph.D. at Hebrew University in 1981. His dissertation was A New Numerical Solution for the Stamp Problem and his thesis advisor was Gregory I. Eskin.[3] In 1981 and 1982 he was also a Visiting Professor at Ohio State University where he taught undergraduate mathematics.[4][2]

From 1984 to 1989 he was a Professor of Mathematics at the University of Iowa.[5] From July 1987 to November 1990 he was Vice President of Software Development at CompuDoc, Inc.[5]


Cut-the-knot (CTC) was a free, advertisement-funded educational website which Bogomolny maintained from 1996 to 2017. It was devoted to popular exposition of various topics in mathematics. The site was designed for teachers, children and parents, and anyone else curious about mathematics, with an eye to educating, encouraging interest, and provoking curiosity.[6] Its name is a reference to the legend of Alexander the Great's solution to the Gordian knot.

CTC won more than 20 awards from scientific and educational publications,[7] including a Scientific American Web Award in 2003,[8] the Encyclopædia Britannica's Internet Guide Award,[1] and Science's NetWatch award.[9]

The site was remarkably prolific and contained extensive analysis of many of the classic problems in recreational mathematics including the Apollonian gasket, Napoleon's theorem, logarithmic spirals, The Prisoner of Benda, the Pitot theorem, and the monkey and the coconuts problem. Once, in a remarkable tour de force, CTC published 122 proofs of the Pythagorean theorem.[10]

Bogomolny did indeed entertain but his deeper goal was to educate. He wrote a manifesto for CTC in which he said that "Judging Mathematics by its pragmatic value is like judging symphony by the weight of its score."[11] He describes the site as "a resource that would help learn, if not math itself, then, at least, ways to appreciate its beauty." And he wonders why it is acceptable among otherwise well-educated people "to confess a dislike and misunderstanding of Mathematics as a whole."[12]

Many mathematical ideas are illustrated by applets. CTK wiki (powered by PmWiki) extends the main site with additional mathematical content, especially that with more complicated formulae than available on the main site.

Personal life[edit]

Bogomolny had to leave academia because he had an uncorrectable hearing problem and was practically deaf in latter years.[13]


  1. ^ Cut The Knot!, by Alex Bogomolny Mathematical Association of America
  2. ^ a b Interview with Alexander Bogomolny MathTango, March 2, 2014
  3. ^ a b Alexander Bogomolny at the Mathematics Genealogy Project
  4. ^ Alexander Bogomolny resume
  5. ^ "Alexander Bogomolny, creator of Cut the Knot, has died". Retrieved 2018-07-09.
  6. ^ "Cut-the-Knot's list of awards". Retrieved 2006-01-18.
  7. ^ "Scientific American 2003 Sci/Tech Web Awards: Mathematics". Retrieved 2006-01-18.
  8. ^ "Site Visit: Mathematical Wonders". Science. 285 (5424). 1999-07-02.
  9. ^ Cut-the-Knot: Proofs of the Pythagorean Theorem
  10. ^ Alexander Bogomolny Natural
  11. ^ "Cut-the-Knot's manifesto". Retrieved 2006-01-18.
  12. ^ Obituary of Alexander Bogomolny By Gary Ernest Davis in Crikey Math, July 13, 2018

External links[edit]