David Breyer Singmaster (born 1939, USA[1]) is a retired professor of
mathematics at
Contents 1 Career 2 Rubik's Cubes 3 Puzzles 4 Singmaster's conjecture 5 Media appearances 6 Personal life 7 Publications 7.1 Books 7.2 Reference works 7.3 Newsletters 7.4 Articles 8 See also 9 References 10 External links Career[edit]
The power of conjugation ... was the last point I understood; I remember lying awake thinking about it, seeing that I could move any four edges into the working locations and realising that this completed the general method for restoring the cube to its original state. –David Singmaster, Moral and Mathematical Lessons from a Rubik Cube, New Scientist, 1982 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.[3] Some other mathematicians
at the conference, including John Conway and Roger Penrose, already
had one.[3]
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.[3] He
has said that it took him "two weeks, on and off" to find a general
solution for the Cube.[9] He devised his notation for recording moves
(now known as the Singmaster notation) in December 1978.[6] In June
1979 he wrote one of the first articles about the Cube in The Observer
newspaper.[10]
In October 1979 he self-published his Notes on the "Magic Cube".[11]
The booklet contained his mathematical analysis of Rubik's Cube,
allowing a solution to be constructed using basic group theory.[12] In
August 1980 he published an expanded 5th edition of the book retitled
as Notes on Rubik's "Magic Cube".[11] It included the results of his
correspondence with other "cubologists", and included details on
monotwists, U-flips, Cayley graphs, and wreath products.[12] The book
contained his own "step by step solution" for the Cube,[13] and it is
accepted that he was a pioneer of the general
Scream HOORAY!! Buy a round of drinks. Send me a cheque. Tell the orderlies that they can let you out now. Etc. etc.[13] The book also contained a catalogue of pretty patterns including his
"cube in a cube in a cube" pattern which he had discovered himself
"and was very pleased with".[15] In 1981, at the height of the Rubik's
Cube craze, the book was republished by Penguin Books, with a US
edition by Enslow Publishers.[11] There were also Dutch and Spanish
translations.[11] He estimates that he sold around 50 to 60 000
copies of his book.[3] Much of the mathematical content of the book
was later reworked by Alexander H. Frey in collaboration with
Singmaster to create their Handbook of Cubik Math published in 1982.
Singmaster has been described as "one of the most enthusiastic and
prolific promoters of the Cube".[16] In September 1981 he was said to
be devoting "almost 100%" of his time to promoting, reporting,
marketing and analysing the Cube.[17] He soon began publishing a
quarterly newsletter called the Cubic Circular which was published
between 1981 and 1985.[3][17]
Puzzles[edit]
Singmaster has one of the world's largest collections of books on
recreational mathematics, which he reported in 1996 contained over
4700 works.[18] He also collects books on cartoons, humour, and
language.[3] He has a huge collection of mechanical puzzles, which he
stated in 2003 contained "perhaps 3000 puzzles, of which about 400 are
Rubik Cubes and variants".[3]
From around 1980 to 1982 he ran his own puzzle company, David
Singmaster Ltd, which stocked "over 100 puzzles and books".[19]
However the venture lost him "a fair amount of money" and led to
prolonged tax negotiations.[7] He referred to this period of his life
as "a massive overdose of cubism".[7]
Singmaster is both a puzzle historian and a composer of puzzles, and
he describes himself as a "metagrobologist". Many of his puzzles have
appeared in publications such as BBC Focus, Games & Puzzles, the
Los Angeles Times, and the Weekend Telegraph.[20] He published a
collection of his puzzles in his 2016 book Problems for
Metagrobologists.[20] From around 2006 Singmaster was a director at
the New York-based Conjuring Arts Research Center, retiring from the
position (becoming Director Emeritus) in 2013.[21] He was instrumental
in the re-discovery of one of the world's oldest books on puzzles and
magic illusions when he came across a reference to the work in a
19th-century manuscript. The recovered text, De viribus quantitatis
(English: On The Powers Of Numbers) was penned by Luca Pacioli, a
Franciscan monk who lived around 1500.[22]
Singmaster's conjecture[edit]
Main article: Singmaster's conjecture
In combinatorial number theory,
Notes on Rubik's "Magic Cube", David Singmaster. Enslow Publishers,
1981. ISBN 0-89490-043-9
Handbook of Cubik Math,
Reference works[edit] Chronology of Recreational
Newsletters[edit] Cubic Circular magazine published 1981-5 by David Singmaster
(available online at Jaap's
Articles[edit] Moral and Mathematical Lessons from a Rubik Cube by David Singmaster,
New Scientist, 23/30 December 1982
The Unreasonable Utility of Recreational
See also[edit] How to solve the Rubik's Cube References[edit] ^ a b "
External links[edit]
v t e Rubik's Cube
Ernő Rubik Uwe Mèffert Tony Fisher Panagiotis Verdes Oskar van Deventer Rubik's Cubes Overview 2×2×2 (Pocket Cube) 3×3×3 (Rubik's Cube) 4×4×4 (Rubik's Revenge) 5×5×5 (Professor's Cube) 6×6×6 (V-Cube 6) 7×7×7 (V-Cube 7) 8×8×8 (V-Cube 8) Cubic variations Helicopter Cube Skewb Square 1 Sudoku Cube Nine-Colour Cube Void Cube Non-cubic variations Tetrahedron Pyraminx
Octahedron
Dodecahedron
Icosahedron Impossiball Dogic Great dodecahedron Alexander's Star Truncated icosahedron Tuttminx Cuboid
Virtual variations (>3D) MagicCube4D MagicCube5D MagicCube7D Magic 120-cell Derivatives Missing Link Rubik's 360 Rubik's Clock Rubik's Magic Master Edition Rubik's Revolution Rubik's Snake Rubik's Triamid Rubik's Cheese Renowned solvers Erik Akkersdijk Yu Nakajima Bob Burton, Jr. Jessica Fridrich Chris Hardwick Rowe Hessler Leyan Lo Shotaro Makisumi Toby Mao Tyson Mao Frank Morris Lars Petrus Gilles Roux David Singmaster Ron van Bruchem Eric Limeback Anthony Michael Brooks Mats Valk Feliks Zemdegs Collin Burns Lucas Etter Solutions Speedsolving Speedcubing Methods Layer by Layer CFOP Method Roux Method Corners First Optimal Mathematics God's algorithm
Superflip
Thistlethwaite's algorithm
Official organization World Cube Association Related articles
Authority control WorldCat Identities VIAF: 111131286 LCCN: n80157141 ISNI: 0000 0000 8303 0053 GND: 1106839536 MGP: 32 |

Time at 25405758.9, Busy percent: 30

***************** NOT Too Busy at 25405758.9 3../logs/periodic-service_log.txt

1440 = task['interval'];

25405860.316667 = task['next-exec'];

25404420.316667 = task['last-exec'];

daily-work.php = task['exec'];

25405758.9 Time.

10080 = task['interval'];

25414500.333333 = task['next-exec'];

25404420.333333 = task['last-exec'];

weekly-work.php = task['exec'];

25405758.9 Time.

1440 = task['interval'];

25405860.35 = task['next-exec'];

25404420.35 = task['last-exec'];

PeriodicStats.php = task['exec'];

25405758.9 Time.

1440 = task['interval'];

25405860.383333 = task['next-exec'];

25404420.383333 = task['last-exec'];

PeriodicBuild.php = task['exec'];

25405758.9 Time.

1440 = task['interval'];

25405860.433333 = task['next-exec'];

25404420.433333 = task['last-exec'];

cleanup.php = task['exec'];

25405758.9 Time.

1440 = task['interval'];

25405860.55 = task['next-exec'];

25404420.55 = task['last-exec'];

build-sitemap-xml.php = task['exec'];

25405758.9 Time.