Mathematica
MathWorld
Wolfram|Alpha
Wikipedia Math
Math GamesMaterial added 30 December 2012
- Mathematica 9 Launched
- Mathematica 9, available in a home edition, has been released.
- Museum of Mathematics Opens
- The Museum of Mathematics has opened in Manhattan. Here's a video tour, a NY Times article, a Wolfram blog, and their facebook page. Here's two shots of my dad (Ed Pegg) playing around on some of the gadgets there, a picture of me (Ed Pegg Jr) at the front door, and some of the tilework for the founders.
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- Symmetric 11-Venn Diagram
- The first symmetric 11-Venn diagram has been found.
- Lines on a Cubic Surface
- 24 lines on a cubic surface happens to be Zome-constructable. I would love to see this as a puzzle made with 24 identical spiraled rods, made as thick as possible. Construction by Scott Vorthmann.
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- Tilings of Rectangles by Squares
- An n×m rectangle can be tiled with a minimum k squares. Can rectangle of size 2(n×m) be tiled with k-1 or fewer squares? That's stackexchange question 240277, and it feeds into data compiled by Bertram Felgenhauer, Tiling rectangles by a minimal number of squares. So far, no rectangles have been found that require fewer squares at a higher multiple. I've extended known results to order 160.
- Triangle Centers
- I liked this app showing the first 1000 triangle centers. These are the same as from the Encyclopedia of Triangle Centers, which are also featured in Cubics in the Triangle Plane. Many of these points can be gotten through the MathWorld packages, though it would be preferable for ETC to have a download area with the list of equations.
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- Census Dotmap
- Brandon Martin-Anderson put together a Census Dotmap, where everyone in the US census is represented by a dot. Slightly more detailed than Gridded Population Data.
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- Man Riding Lady Perspective Illusion
- I liked this picture.
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- Theo Geerinck version of a Sicherman's Triabolo Puzzle
- George Sicherman: Here are the four triaboloes. Arrange them to make a figure (1) with horizontal and vertical symmetry; (2) with symmetry about both diagonals. The solutions are unique. You may flip the pieces over, or turn them in 90-degree increments. [Ed-Theo Geerinck made a physical version]
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- The Colonel's Christmas Puzzle
- George Sicherman: Merry Christmas to all you mathematicians! I've attached a present for you. It's my newest puzzle, Quadrexity. Just carve the six pieces out of any convenient material--wood, foam rubber, Gouda cheese--or do a little surgery on a set of Quintillions. Paint the pieces in cheerful colors as shown. Then put the pieces together to make a cube. (Ed - For more puzzles of this type, see Puzzles Will Be Played. For solutions, see Burr Tools).
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- Aerographite
- A solid material that is lighter than air has been found: Aerographite. There is also an aerographite wikipedia page. If you thought packing peanuts were the most annoying packing material, they have nothing on aerographite. A cubic meter block would weigh 200 grams. A cubic meter of air weighs 1200 grams.
- My latest anagrams
- Telecommunication overdramatising MEDICAL TESTS!! ? = Commercial Advertisement Loudness Mitigation Act.
"The republic has no need for genius." = Bureau of Enlightened Censorship.
Incompetent to stand trial? You ~ cry "Lead Us Not Into Temptation!"
Seasonal affective disorder = Faint solar cover fed disease.
The Island of Misfit Toys = Sysadmin's fiftieth tool.
Clench your fist at ~ "The Fiscal ..." country.
Republicans = I curse Plan B. - The Lament of Icarus (each line an anagram)
- Loutish Cretan fame:
Utter chaos in flame.
Final test hour came --
Macho, tan -- flies true!
Father - "Um, at ceil, son."
Altimeter focus - nah.
Smile at hot furnace.
Aloft: "Race me - hit sun!"
Set afire: human colt.
Is feather, can moult.
Culminate: sea-froth.
Hoist cruel fate, man.
Locate human strife.
Mourn that ace's life. - Canario
- Miguel Palomo sent me the logic puzzle Canario, a sudoku-like puzzle on a triangle.
- Knot Puzzle
- The cover of Mathematical Mind-Benders answers a question -- can the 3 projections of a closed loop all be trees? Adam Goocher extends the problem with 2 more conditions: 1. the cycle must be knotted, and 2. the cycle must have order-3 rotational symmetry. His best answer is an order 11 knotted loop.
- Intelligence Puzzle
- Franz Pichler: Watching 'Homeland' inspired me to do this one: NSA + CIA / DHS - FBI = USA (1 solution with 3 digit numbers).
- Jerry Andrus Illusion Book
- Al Seckel has put together an iPad interactive book devoted to Jerry Andrus' illusions. You can also visit JerryAndrus.org, or the Jerry Andrus wikipedia page.
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- Chinese Satellite Visits Asteroid Toutatis
- I liked this infographic on the Toutatis flyby.
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- My Picture at Facebook
- Just in case you wonder what I look like, here's my picture at Facebook. You can also follow me at Twitter. Happy New Year, everyone. Sometime soon, this site will have its 5th million visitor.
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Material added 28 Nov 2012
- Mazelog
- David Johnson-Davies: Ed, I enjoyed your article on Multi-State Mazes on the MAA web site. I was also inspired by Robert Abbott's maze books, and have produced a web site of original logic mazes. [Ed - A very nice site]
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- Mrs. Perkins's Quilts
- Stuart Anderson has updated the Mrs. Perkins's Quilt problem to order 29. Starting with order 6, the sequence 3, 4, 5, 6, 8, 10, 14, 18, 24, 30, 40, 54, 71, 92, 121, 155, 210, 266, 360, 476, 642, 833, 1117, 1473, 1967 gives the smallest square of that order, so far as is currently known.
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- Billiard Ball in a Dodecahedron
- Franz Pichler: I have found the perfect symmetrical 3D billiard path in a Dodecahedron. This is an improvement to a result of M. Hudelson [MAA & AMS Meeting, 1997], which presented 'periodic omnihedral billiards' (a billiard path inside platonic solids, which hits each face once and returns to it's starting point and going on with initial direction building a closed cycle). The path has only two different hitting points (relative to the pentagon-faces), with the six points near the main diagonal having the same positions on their faces, which guaranties exact 3-fold rotation symmetry around the main diagonal of the dodecahedron.
SymmetricPath = { {585 - 69 Sqrt[5], 348 - 116 Sqrt[5], 30 + 108 Sqrt[5]}, {957 - 261 Sqrt[5], 348 - 116 Sqrt[5], -696 + 174 Sqrt[5]}, {-29 - 203 Sqrt[5], 348 - 116 Sqrt[5], 928 - 406 Sqrt[5]}, {187 - 191 Sqrt[5], -84 - 140 Sqrt[5], 478 - 112 Sqrt[5]}, {277 - 41 Sqrt[5], -264 + 256 Sqrt[5], -362 - 4 Sqrt[5]}, {493 - 29 Sqrt[5], -696 + 232 Sqrt[5], -812 + 290 Sqrt[5]}, {-493 + 29 Sqrt[5], -696 + 232 Sqrt[5], 812 - 290 Sqrt[5]}, {-277 + 41 Sqrt[5], -264 + 256 Sqrt[5], 362 + 4 Sqrt[5]}, {-187 + 191 Sqrt[5], -84 - 140 Sqrt[5], -478 + 112 Sqrt[5]}, {29 + 203 Sqrt[5], 348 - 116 Sqrt[5], -928 + 406 Sqrt[5]}, {-957 + 261 Sqrt[5], 348 - 116 Sqrt[5], 696 - 174 Sqrt[5]}, {-585 + 69 Sqrt[5], 348 - 116 Sqrt[5], -30 - 108 Sqrt[5]} }. -
- Erich Friedman's Holiday Puzzles
- Erich Friedman: Here is my usual batch of holiday puzzles. #2 Number Wreath. Put the digits 1 through 5 into five of the circles below. If a circle contains the digit n, then the circles that are n clockwise and n counterclockwise from that circle should also contain digits.
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- Not NPR Puzzles
- Will Shortz doesn't always go for the puzzles I send him.
Take the phrase AM I THE ONLY ONE. Add four letters from the word TUNNEL to get something that has a tunnel. What is it?
Take the phrase "RAWLY DISTRAUGHT" Add in the letters of the first five odd numbers to get something that is an even number. What is this final number?
Take the word BRIGANDRY, as in something Robin Hood was accused of. Add a letter to Brigandry and rearrange to get a popular program. - Android Programs
- I have an iPod Touch, an iPad, a Nexus 7, and a Nexus 4. I have come to like the Android market more than the iOS market. Some Android favorites: Simon Tatham's Puzzles, Laser Tank, Midi Sheet Music, Delver, Hovernote, Freenote+, Box, NY Times, Creatorverse, DarkMaze, Vexed, HyperRogue III, Continuity 2, Lines of Action, Miracle Octad Generator, Generations, and Langton's Ant. I also like Android for being Midi friendly, so that I can have a playlist for things like Piano Roll Midis.
- Lights Out on a Graph
- Leslie E. Shader: Hi Ed, I looked at the Puzzle competition items last night and have made a new LIGHTS OUT puzzle with it. Have you noticed Jaap's new app, Lights Out on a Graph? With it you can enter any graph you want and create a LIGHTS OUT puzzle with lights the nodes of your graph. You can also choose a graph from a shared file (File/Download) or upload your puzzle to the shared file. I have contributed more than 200 graphs to the shared file. Several have come from graphs appearing in mathpuzzle. These I have identified with your name. I encourage you to try some of these and would like some feedback. My main interest is trying to find solution strategies that can be used without computer calculations. Your "13 Triangles" (my EDS_13_TRIANGLES) has a strategy different from the usual. Likewise for the other graphs with your name attached. Let me know if you are successful in finding some strategies.
- Multiple Pentahex Compatibility
- George Sicherman: This polyhex can be tiled with any of 13 different pentahexes!
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- Aggregating Pentapents
- George Sicherman: Ed -- You have probably seen Ali Muñiz's "minimal cover" problem, which is to find a minimal polyomino containing all the tetrominoes, or all the one- sided pentominoes, or whatever. I call it the aggregation problem, and I've been studying it for polypents. (Ali recognizes that the problem can be adapted to any polyform.) I was hoping to find an 11-pent that contains all 25 pentapents, but alas! The best I could do is 24. I attach one example. You should have no trouble seeing where to add a cell to realize the W pentapent. I no longer believe that your problem of arranging the pentapents to form five congruent 25-pents is impossible. I still believe that it is intractable! (That too could change.)
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- Symmetric Figure from S U Y
- George Sicherman: These are the S, U, and Y tetrahexes. Join them to make a symmetric figure. The solution is unique.
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- Ancient Icosahedron
- The Met has a collection of ancient d20s.
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- Mathematical Olympiad Dark Arts
- Adam P. Goucher: All thirteen chapters of Mathematical Olympiad Dark Arts can now be downloaded and viewed.
- Stella 5.0
- One of the best programs for exploring polyhedra, other than vZome, is Stella, and it just got an update to Stella 5.0. With it, you can get double-tabbed nets for things like the Stellation of Small Stellated Truncated Dodecahedron.
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- Anchor Stone Puzzle Book
- Jerry Slocum introduced The Anchor Puzzle Book earlier this year, based on puzzles made from stone.
- Cubic Calendars
- Mark Michell: I have just put up a page with various cubic calendars in the form "ddmmmyy" (to be read as "mmmddyy" by US readers) i.e. "01" to "31" for the days of the month, "jan" to "dec" for the month and "12" to "43" for the year. I have also included solutions for 57 languages, including some with non-Roman alphabets. (Ed - Something to go with the Daily Puzzle)
- Sic Bo
- Martin Gardner talked about the game Chuck-a-Luck. A player bets on a number 1-6, then 3 dice are rolled. If the chosen number appears 1, 2, or 3 times, the player wins 1, 2, or 3 times their bet. A novice might think that there is a 50% chance for a 1 to appear with 1 out of 6 three times, but that's not the right analysis. This game is now a small part of Sic Bo, which includes many other types of bets. I learned of it while perusing onlinecasino.ca, which is a decent place to research casino related games. Another casino site casinosafari goes into more detail on the advanced betting options in sic bo, as well as featuring casinos where you can play this game.
- Langford Pairing
- I noticed that the Google logo has Langford Pairing, with red, blue, and other color pairing. (John Miller's Langford Pairing page is well worth a look)
- Domino Cards
- I made a double-9 domino game based on highest/lowest (ups and downs). Jared McComb pointed out *difference* made it a triangle. Remove the card 36, and half the deck has lower lowest, higher highest, or lower difference -- and makes a perfect Venn diagram with 36 at the center.
00 01 02 11 12 13 22 23 24
03 04 05 06 14 15 16 25 26
07 08 09 17 18 19 27 28 29
33 34 35 44 45 46 55 56 66
57 67 68 77 78 79 88 89 99
37 38 39 47 48 49 58 59 69
Can any neat magic tricks be done with a deck of domino cards? - Draining sink-eye
- Clink image for larger version.
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- Anagrams
- Nate Silver ~ is relevant.
Auguste Rodin sculpture = "Gratuitous nude" scruple.
D. Petraeus = Super date! (by db)
Hostess Twinkies ~ Owe. Skittishness.
Romney's "binder" splat = Temporary blindness
Alpha Centauri Bb = Unhabitable. Crap!
No tea? Throw ~ hot water on.
Answer to Life, the Universe, and Everything = Slart: "One, three, five, seven, nine, ... dig thruway." - Supermagnets in copper tubes
- [1210.7796] Magnet traveling through a conducting pipe: a variation on the analytical approach
arxiv.org - 9-gigapixel picture of the galaxy
- I like the gigapixel view of the galaxy.
Material added 24 Oct 2012
- The Fool and his Money
- Cliff Johnson's long awaited sequel to The Fools Errand (my favorite computer game from 1987) will be released on 26 October -- The Fool and his Money. I pre-ordered it ten years ago, making me one of the faithful.
- Martin Gardner Celebration of the Mind
- There are meetings all over the world this week and next for Martin Gardner's 98th birthday, with a listing at g4g-com.org. I'll be at the third such meeting in the Champaign-Urbana Illinois branch.
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- Daily Puzzle
- Oskar van Deventer and Wei-Hwa Huang invented the Daily Puzzle, and of course it's very nice.
- Dudeney's Star Puzzle
- The task of the star puzzle, ((X36 = AM329) according to the list [Knu] by Donald E. Knuth) published a century ago in The Strand Magazine [Dud2], is to construct a path, consisting of 14 straight strokes, on the following field of stars from one light star to the other such that all the stars lay on the path. Dudeney claimed that it is impossible to do the task in 14 queen moves. Alex Ravsky found that there actually is queen move solution for the Dudeney Star Puzzle.
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- Al Zimmermann's Programming Contests
- Straight Lines is a upcoming programming challenge with a prize.
- Smooth Life
- The cellular automaton Smooth Life has remarkably life-like behavior. Also on Sourceforge. In a similar vein, Golly is now available for iPad.
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- Domino Cards
- My initial idea I've long been a fan of domino playing cards, and recently found Bicycle Double-9 Domino Cards. I think card based table and gambling games based on dominoes could do quite well. I also really liked the Vanda set of perfectly symmetrical playing cards over at Kickstarter. I'm not sure if these new decks would help with various casino games.
- Holeless Variants
- George Sicherman: Livio Zucca's Pento-Tetro-Trominoes now have holeless variants. New and improved solutions are welcome.
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- Alpha Centauri Bb == Unhabitable. Crap!
- A planet was discovered, so I made the anagram in the title. Tour de France = Center o' fraud. Another anagram. Presidential debates = In late, desperate bids. And a third. Most of these I post at my Facebook page.
- Amazing coincidence
- In 1918, two teenagers became buddies after both lying about their ages, then training to be ambulance drivers for the Red Cross. One of them got the Spanish flu, but survived, and soon after that the war was over. Walt Disney and Ray Kroc (McDonalds).
- Google Earth Fractals
- Paul Pourke has put together an excellent list of Google Earth Fractals.
- Google Langford Pairing
- Have you ever noticed that the Google logo is a Langford pairing? Other, blue, red.
- Element 113 Proven
- Element 113 is proven. I hope they call it Japanium, symbol J.
- The Comet of 2013
- A potentially very bright planet will be coming to the skies in November 2013. There is also the Hubble Extreme Deep Field.
Material added 26 August 2012
Recursive haiku!
You can enjoy it only
after you read a
Material added 4 Jun 2012
- The Anchor Puzzle Book
- Jerry Slocum has put together a gorgeous book on the Anchor Puzzle. Only took him about 30 years, on and off. Here's his flyer for the Anchor Puzzle Book.
- Transit of Venus
- The Transit of Venus happens on 5 June. Won't happen again until 2117.
- One Octillion Sonnet Anagrams
- Mike Keith has put together an octillion sonnet anagrams. Go claim yours while they last.
- Wrinkled Torus
- A square can become a torus without deformation.
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- G-U puzzles
- Two phrases contain all but two of the letters from G to U, plus a few extra letters. What are they? Answers are at my Facebook page.
1. Very famous puzzle.
2. Method taught in HS Algebra.
In a similar vein, the full name of industrialist B. F. Goodrich has all the letters from A-O. - Divide a Hexagon, and a Tiling App
- Puzzle: divide a hexagon into 12 identical non-convex hexagons so that some of them don't touch the center of the hexagon. An answer can be found at Jaap's Tiling Page. Also on tiling is a recent paper on Isoperimetric Pentagonal Tilings.
- Tetris
- On June 6, 1984, Alexey Pajitnov wrote a program allowing people to Play Tetris for the first time.
- Three-Pentomino Balanced Rectangles
- George Sicherman: I've put up a page of balanced three-pentomino rectangles. Also, find a polyomino that can be tiled with any of six different pentominoes, one of which is the Z pen-
tomino. Solution. This can be done with any designated pentomino. It's just that Z is the hardest! -
- Strictly Isosceles
- Enigma Mensa: Beginning with an equilateral triangle, can you divide it into a number of acute, strictly isosceles triangles? Here's a solution with 21 triangles. Can you find a solution with 18 triangles or 17 triangles, or fewer?
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- Thorium Anomaly
- The moon has a permanent warm spot known as the Thorium Anomaly.
- Scavenger Hunt
- The University of Chicago Scavenger Hunt for 2012 was really quite insane.
- 4K fractal program
- The output of the small program Hartverdrahtet is really quite incredible.
- How to win Battleships
- For winning Battleships, don't spend 300M on a silly movie. Instead, use some computer algorithms for winning Battleships. I found Tetris Trailer 1 and Tetris Trailer 2 more watchable than the Battleships trailers.
- Polyhedra Visualizations
- I really like this page on unusual polyhedra.
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- Iron Man 2 -- Stark Effect
- Tony Stark finds that his father was working on the Stark effect in Iron Man 2. Further explanation is at the Wikipedia page, Stark Effect.
- Brain Zaps Improve Math Skills
- The Univeristy of Oxford claims small brain zaps help math skills. I'd be skeptical.
- Optimal Steiner Quintuple Ellipses
- Here is a resolvable Steiner quintuple system. Every tuple from 1-25 appears in exactly one of the sets.
{{1,2,3,4,5},{6,7,8,9,10},{11,12,13,14,15},{16,17,18,19,20},{21,22,23,24,25},
{1,6,11,16,21},{2,7,12,17,22},{3,8,13,18,23},{4,9,14,19,24},{5,10,15,20,25},
{1,7,13,19,25},{2,8,14,20,21},{3,9,15,16,22},{4,10,11,17,23},{5,6,12,18,24},
{1,10,14,18,22},{2,6,15,19,23},{3,7,11,20,24},{4,8,12,16,25},{5,9,13,17,21},
{4,6,13,20,22},{25,2,9,11,18},{16,23,5,7,14},{12,19,21,3,10},{8,15,17,24,1},
{4,18,7,21,15},{6,25,14,3,17},{13,2,16,10,24},{20,9,23,12,1},{22,11,5,19,8}}
It's possible to cover this as a point system with ellipses and circles. An optimal covering would be one where each ellipse and circle clearly went through exactly 5 points, and didn't come close to any others. Is there a good way to optimize this? I posted this at math.stackexchange. -
Material added 22 April 2012
- Magic Tile
- The Magic Tile program has been greatly updated. The simplest version gives an equivalent of Rubik's Cube, but this allows many different tessellations to provide the underlying group.
- The Inaba point placement problem
- What is the smallest number of points that cannot be covered with unit circles? As a motivator, put 7 identical coins together with 6 around the center coin, then scatter 10000 points randomly in that area. Some of those points will be in the triangular cusps between the coins. No matter how the coins are moved, the points cannot be covered. Bob Hearn has found an uncoverable set of 45 points, which is a new record. 12-45 is the bound of the problem.
- fusible numbers update
- A year and a half ago, I introduced Jeff Ericksen's Fusible Numbers, those numbers measurable by irregularly burning 1 minute fuses. A recent Survey on fusible numbers has challenged some of the results from that program. It's obviously a very hard problem. There is also fusible discussion on Stack Exchange.
- P&A Magazine
- From joedev: pandamagazine.com is an excellent magazine devoted to puzzles and puzzle hunts
- 17 clues necessary for sudoku
- It has been proved that 16 clues is not enough for 9x9 sudoku. Toshihiro Shirakawa has constructed a 56 clue 16x16 sudoku puzzle, and a 170 clue 25x25 sudoku puzzle.
- Gaussianos - recreation math site in Spain
- Gaussianos is Spain's leading math recreations site, recommended to me by Bernardo recaman
- Gamepuzzles.com Site Update
- Kate Jones' site, gamepuzzles, has been updated in a big way. Among other things, my old sets of stacked octiamonds are available for sale. She also has a few copies of Sequential Squares left, which is the most prominently displayed puzzle of my whole collection.
- Who Goes First?
- Eric Harshbarger, with help from Robert Ford, has fulfilled a dream of James Ernest by making a set of 4 12-sided dice which can be rolled to determined who goes first in a game. No die has an advantage over any other die, and ties are impossible. Two of these dice have numbers 1, 8, 11, 14, 19, 22, 27, 30, 35, 38, 41, 48 and 2, 7, 10, 15, 18, 23, 26, 31, 34, 39, 42, 47. Can you figure out how the digits are distributed for the other two dice?
- T H Willcocks turns 100
- T. H. Willcocks, the first to make a perfect squared square, turned 100 on 19 April 2012.
- Thomas Rodgers has died
- The Gathering for Gardner sites and conventions were all a labor of Thomas Rodgers. He died on April 10th, just 10 days after G4G 10 had a final party at his house. Though very ill, he met privately with various guests there. Donations can be sent to the Gathering for Gardner foundation, at:
Gathering 4 Gardner
C/O Scott Hudson, Secretary-Treasurer
5475 Fulton Industrial Blvd.
Atlanta, GA 30336 - Inaba Puzzles
- Naoki Inaba has been updating inabapuzzle.com. Part of the site is his Room full of puzzles, which is well worth putting through google translate. He also runs the puzlab twitter.
Material added 27 March 2012
- Salt Mazes
- James Dalgety: Mazes made from salt.
- Three Tetromino Puzzle
- A great new puzzle from George Sicherman: Using 3 of the 5 different tetrominoes (tetris shapes), make a figure with rotational symmetry. The solution is unique!
- DROD: Gunthro and the Epic Blunder
- The next game in the greatest puzzle game series of all time is available for pre-order at Caravel Games.
- Escher Animated
- Vladimir Bulatov has put up some fantastic Escher animations.
- Martin Gardner issue
- The Martin Gardner issue of College Mathematics Journal is available free online.
- Generations
- We're at 7787 Demonstrations right now. One I added recently was on the Generations Cellular Automata.
- Entry of the Gladiators = Target day for the lions.
- Just an anagram I found.
- A Desk Musicbox Puzzle
- Master puzzlemaker Kagen Schaefer has completed his largest work -- a desk musicbox.
- MIT Mystery
- Back in January, the latest MIT Mystery Hunt was inflicted upon its participants.
- 13 Unique Consonants
- Microwavable heating pad has 13 unique consonants, which I believe is a record for a common phrase. With 12 unique consonants: speed of light in a vacuum, and The Lumberjack Song.
- Rolling Cube Puzzle
- Dave Langers: I noticed a rolling-cube puzzle in your latest MathPuzzle entry (compliments for the great work, by the way, I visit your site regularly!). This reminded me of a puzzle I thopught of some time ago, and that I now put on paper (see the attached RollingCube.pdf). The basic idea is to roll a cube around with the goal to let it end up at the same location where it started but with a different specified orientation, where some rolls are allowed and others are forbidden. The PDF should be self-explanatory. Perhaps fun to mention is that the three examples in the file give precisely the three cube configurations with the longest such solutions (if my exhaustive search hasn't fooled me); yet the one with the longest solution isn't necessarily the most difficult one. All can be done in 30 moves or less.
Material added 19 February 2012
- The Gauss Christmath Special
- Vi Hart skewers the 12 Days of Christmas with her offering The Gauss Christmath Special. Also, a puzzle by her dad (George Hart) called Frabjous is available, it's suitable for star-shaped needs.
- Schutte 67
- Sándor Bozóki: 0-++-+-++--+++----+-+------++-+++-+---+--++++++-+-++++---++--+-+--+. I have read your paper Tournament Dice, which was totally new for me. If I understand correctly, one of the open questions is that what is the minimal graph for 5 players. As I adopted the idea described in your paper, I found that the minimal size with this construction is 67. It is the sequence at the start of this message, with 0=0, +=+1, and -=-1, rotated through 67 positions.
- So What The Heck Have I Been Doing?
- In December, I found out that my local library has a fantastic video collection, including almost all of the IMDB Top 250. I started watching the great movies over the holidays, sometimes three or four a day. I've now seen all of them except A Separation. An addiction to great movies is a somewhat limiting obsession, since it's a finite resource. I delved down into almost half of the movies in the Top 1000 as well. I just watched Adaptation., which deals with obsessions and writer's block, and that seemed like a good ending point for my movie delving. I've also been doing a lot of reviews, and managed to become an Amazon Top 50 reviewer.
- Puzzle Play Helps Boost Learning Math-Related Skills
- Children who play with puzzles between ages 2 and 4 later develop better spatial skills, a study by University of Chicago researchers has found. Puzzle play was found to be a significant predictor of spatial skill after controlling for differences in parents' income, education and the overall amount of parent language input. (Read the full Science Daily article)
- Google Correlate
- Over at Google Correlate, you can draw a graph and data that fits with that will be found for you. Also, for some reason, "free spanish translation" is strongly correlated with "math puzzle".
- Slocum Puzzle Collection Online
- The huge Slocum Puzzle Collection is now online.
- Pizza Slice Packing
- The packing of pizza slices is explored at the Jan 2012 Math Magic.
- A Sudoku Puzzle Needs at least 17 Clues.
- Gary McGuire: I know you have posted and written about sudoku. You might have some interest in the minimum number of clues problem, so I write to let you know that we have completed the exhaustive search for a 16-clue sudoku puzzle, and the result is that none exists. Therefore we have solved the problem, and 17 is the answer! There is no 16-Clue Sudoku.
- Polyiamond Compatibility
- George Sicherman: I spent this morning working on a new computer program. It promptly rewarded me with the attached compatibility figure for the J pentiamond and X hexiamond. Aren't computers wonderful? I'm so glad I wasn't born 100 years ago!
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- Here is a polyomino that can be tiled by any of seven pentominoes. It has 48 tiles, which improves on Mike Reid's solution with 90 at Jorge L. Mireles's site:
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This figure can be tiled by 15 different heptominoes. The old record was 14 by Robert Reid. You can see it at Jorge Luis Mireles's site:
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Site Goals
Martin Gardner celebrates math
puzzles and
Mathematical Recreations. This site aims to do the same. If you've made
a good, new math puzzle, send it to ed@mathpuzzle.com.
My mail address is Ed Pegg Jr, 1607 Park Haven, Champaign, IL 61820.
You can join my moderated recreational mathematics email list at http://groups.yahoo.com/group/mathpuzzle/. My facebook page is at Ed Pegg Jr.
visitors
since I started keeping track.
