|Born||January 4, 1948|
|Died||July 7, 2018|
|Institutions||Moscow Institute of Electronics and Mathematics, Hebrew University , Ben Gurion University, University of Iowa|
|Thesis||'A New Numerical Solution for the Stamp Problem' (PhD, 1981)|
|Doctoral advisor||Gregory I. Eskin|
Alexander Bogomolny (January 4, 1948 – July 7, 2018) was a Soviet-born Israeli American mathematician. He was Professor Emeritus of Mathematics at the University of Iowa, and formerly research fellow at the Moscow Institute of Electronics and Mathematics, senior instructor at Hebrew University and software consultant at Ben Gurion University. He wrote extensively about arithmetic, probability, algebra, geometry, trigonometry and mathematical games.
He was known for his contribution to heuristics and mathematics education, creating and maintaining the mathematically themed educational website Cut-the-Knot for the Mathematical Association of America (MAA) Online. He was a pioneer in mathematical education on the internet, having started Cut-the-Knot in October 1996.
Education and academic career
Bogomolny attended Moscow school No. 444, for gifted children, then entering Moscow State University, where he graduated with a master's degree in mathematics in 1971. 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 received his Ph.D. in mathematics at Hebrew University in 1981. His dissertation was A New Numerical Solution for the Stamp Problem and his thesis advisor was Gregory I. Eskin. In 1981 and 1982 he was also a Visiting Professor at Ohio State University where he taught mathematics.
Cut-the-knot (CTK) 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. Its name is a reference to the legend of Alexander the Great's solution to the Gordian knot.
CTK won more than 20 awards from scientific and educational publications, including a Scientific American Web Award in 2003, the Encyclopædia Britannica's Internet Guide Award, and Science's NetWatch award.
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, CTK published 122 proofs of the Pythagorean theorem.
Bogomolny did indeed entertain but his deeper goal was to educate. He wrote a manifesto for CTK in which he said that "Judging Mathematics by its pragmatic value is like judging symphony by the weight of its score." 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."
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.
Bogomolny had to leave academia because he had an uncorrectable hearing problem and was practically deaf in latter years. He is survived by his wife Svetlana Bogomolny, two sons David (Israel) and Eli (USA) Bogomolny, and granddaughter Liorah Shaindel Bogomolny.
Bogomolny's older son David chronicled his yearlong recitation of kaddish in honor of his father on The Times of Israel blogs in a series titled, "The skeptic's kaddish for the atheist", consisting of traditional Jewish sources, religious text analysis, modern interpretations and expressions of kaddish, philosophy, theology, eschatology, creative writing, and the personal reflections; memories; and experiences of a son in mourning. 
- Cut The Knot!, by Alex Bogomolny Mathematical Association of America
- Interview with Alexander Bogomolny MathTango, March 2, 2014
- Alexander Bogomolny at the Mathematics Genealogy Project
- Alexander Bogomolny resume
- "Alexander Bogomolny, creator of Cut the Knot, has died". Retrieved 2018-07-09.
- "Cut-the-Knot's list of awards". Retrieved 2006-01-18.
- "Scientific American 2003 Sci/Tech Web Awards: Mathematics". Retrieved 2006-01-18.
- "Site Visit: Mathematical Wonders". Science. 285 (5424). 1999-07-02.
- Cut-the-Knot: Proofs of the Pythagorean Theorem
- Alexander Bogomolny Natural Math.com
- "Cut-the-Knot's manifesto". Retrieved 2006-01-18.
- Obituary of Alexander Bogomolny By Gary Ernest Davis in Crikey Math, July 13, 2018
- "The skeptic's kaddish for the atheist, 51". timesofisrael.com. Retrieved 2019-10-15.