# Roger Penrose

 Roger Penrose Background Information Alias(es): Country: United Kingdom Born: 8 August 1931 Occupation(s): Mathematical physicist Years Active: 1978-9 WCA ID: [1] Claim to Fame: Rubik's Cube theory

Roger Penrose is an English physicist, mathematician, and Nobel Prize Laureate at the University of Oxford in the United Kingdom. He is noted as a cubing theorist in the early days of the Rubik's Cube.

## History

According to David Singmaster, Penrose had already acquired a Rubik's Cube (or "Magic Cube") at the International Congress of Mathematicians in Helsinki in August 1978 where Singmaster first got one. Penrose could already solve his cube. Penrose quickly appreciated the importance of the commutators FR'FR (Sledgehammer) and FRF'R (Sexy Move) and gave them the names Y-commutator and Z-commutator because of the arrangement of the affected corners.[Singmaster, p.17] He was one of the correspondents who wrote to David Singmaster in the earliest days of the Rubik's Cube, and Singmaster mentions him repeatedly in early editions of his Notes on Rubik's "Magic Cube".

## Five Generator Group

By 1979 Penrose was able to show that it is always possible to solve a Rubik's Cube leaving one face of the cube untouched. In mathematical terms: one generator of the Rubik's Cube Group can be ignored and we still get the whole group.[p.18] One of Penrose's complete solutions for this problem was:[p.27]

R2L2UF2B2UF2R2F2B2U2L2U2L2R2U2R2U2R2F2U'R2B2R2L2F2L2UB2F2U = D'

## Edges First Solution

Penrose was also the creator of his own Edges First solution which was said to take "about 100 moves."[p.26] This method appears to have been: D edges, middle slice edges, U edges, then corners in place, then oriented.[p.40]

## Named after Penrose

The Penrose Cube is a shape variant of the Rubik's Cube with three surfaces first manufactured in 2017. It was named by its inventor Antonio Garrido Rubio to honor Roger Penrose. According to Rubio: "looking at the vertex reminded me of the Penrose triangle."[ TwistyPuzzles]

## References

• Singmaster, David, (1981) Notes on Rubik's "Magic Cube", 5th edition. Enslow Publishers. ISBN 0-89490-043-9