David Singmaster

David Singmaster was an American-British mathematician who spent most of his career in London, where he became professor of mathematics at London South Bank University and retired in 1996. He was born on 14 December 1938 and died on 13 February 2023. He studied at the California Institute of Technology and then at the University of California, Berkeley, where he earned his PhD in 1966, and he taught at the American University of Beirut before moving to London in 1970. His academic interests were combinatorics and number theory, and he became one of the leading historians and composers of mathematical puzzles. He is best remembered for the Rubik's Cube: in 1979 he began compiling Notes on Rubik's Magic Cube, which gave the first mathematical analysis of the Cube and introduced the Singmaster notation for recording moves, which became the standard. In combinatorial number theory his name is attached to Singmaster's conjecture, which proposes an upper bound on how many times a number other than 1 can appear in Pascal's triangle.