David Singmaster

David Breyer Singmaster (14 December 1938 – 13 February 2023) was an American-British mathematician who was emeritus professor of mathematics at London South Bank University, England.

He had a huge personal collection of mechanical puzzles and books of brain teasers.

He was most famous for being an early adopter and enthusiastic promoter of the Rubik's Cube.

David Singmaster was a student at the California Institute of Technology in the late 1950s.

His intention was to become a civil engineer, but he became interested in chemistry and then physics.

However he was thrown out of college in his third year for "lack of academic ability".

After a year working, he switched to the University of California, Berkeley.

He only became really interested in mathematics in his final year when he took some courses in algebra and number theory.

In the autumn semester, his number theory teacher Dick Lehmer posed a prize problem which Singmaster won.

In his last semester, his algebra teacher posed a question the teacher didn't know the answer to and Singmaster solved it, eventually leading to two papers.

He gained his PhD from Berkeley, in 1966.

He taught at the American University of Beirut, and then lived for a while in Cyprus.

Singmaster moved to London in 1970.

The "Polytechnic of the South Bank" had been created from a merger of institutions in 1970, and Singmaster became a lecturer in the Department of Mathematical Sciences.

His academic interests were in combinatorics and number theory.

In August 1971 he joined an archaeological expedition off the coast of Sicily, acting as photographer.

He went off course one day and noticed a timber sticking up out of the sand.

This led to the discovery of the Marsala Punic Ship.

Around 1972, he attended the Istituto di Matematica in Pisa for a year having won a research scholarship.

Singmaster's association with Rubik's Cubes dates from August 1978, when he saw a Cube (at that time a rarity) at the International Congress of Mathematicians in Helsinki.

Some other mathematicians at the conference, including John Conway and Roger Penrose, already had one.

Singmaster quickly acquired a Cube (in exchange for a copy of an M. C. Escher book) and was able to solve it by early September 1978.

He said that it took him "two weeks, on and off" to find a general solution for the Cube.

He devised his notation for recording moves (now known as the Singmaster notation) in December 1978.

His Notes on Rubik's "Magic Cube" which he began compiling in 1979 provided the first mathematical analysis of the Cube as well as providing one of the first published solutions.

The book contained his cube notation which allowed the recording of Rubik's Cube moves, and which quickly became the standard.

Singmaster was both a puzzle historian and a composer of puzzles, and many of his puzzles were published in newspapers and magazines.

In combinatorial number theory, Singmaster's conjecture states that there is an upper bound on the number of times a number other than 1 can appear in Pascal's triangle.

In June 1979 he wrote one of the first articles about the Cube in The Observer newspaper.

In October 1979, he self-published his Notes on the "Magic Cube".

The booklet contained his mathematical analysis of Rubik's Cube, allowing a solution to be constructed using basic group theory.

In August 1980 he published an expanded 5th edition of the book retitled as Notes on Rubik's "Magic Cube".

It included the results of his correspondence with other "cubologists", and included details on monotwists, U-flips, Cayley graphs, and wreath products.

The book contained his own "step by step solution" for the Cube, and it is accepted that he was a pioneer of the general Layer by Layer approach for solving the Cube.

If you managed to solve the Cube using his method then Singmaster suggested that you should:

He was promoted to a Readership (a Research Professorship) at the South Bank Polytechnic in September 1984.

The polytechnic college became London South Bank University in 1992, and Singmaster was the professor of mathematics at the "School of Computing, Information Systems and Mathematics".

He retired in 1996.

He became an honorary research fellow at University College London.

He was designated emeritus at London South Bank University in 2020.