Erasable Games Weblog

(Sudoku in words and pictures)

Archive for March, 2008

Mirror Sudoku

Sunday, March 30th, 2008

Mirror Sudoku

There seem to be three kinds of mirroring: What you see in a mirror, mimicry and instant object replication. The first depends on symmetry, the second depends on synchronicity and the third on identity. Andrew Carson of Dungeon7Sciences discusses what a mirror image is about and why the mirror doesn’t show us upside down as well.

In psychological or theatrical terms, mirroring (mimicry) is concurrently copying what someone else is doing (perhaps while communicating with them). Group synchronized dancing (or swimming) are good examples of this. It is called satire when the mimicry is delayed.

In Computer terms, a mirror is an exact copy of data of some extent of storage. On the Web, mirrors contain repositories of desired software or replicated data, useful when there is a surge in demand for a particular article, picture, software program or datum.

There is a description of Mirror Sudoku which requires that the Sudoku puzzle starting number placements be symmetrical horizontally and/or vertically. This puzzle with its starting number positions conforms to horizontal and vertical symmetries.

Remember to draw the numbers slowly and precisely. It’s an alternate universe you’re trying for.

Fillomino On Sudoku

Sunday, March 23rd, 2008

Fillomino On Sudoku

Nikoli invented this puzzle in 2001. Once called Allied Occupation, Fillomino is a merger of the words Filled and Polyomino. A Polyomino describes the shapes assumed of a varying number of multiple cells, that have at least one side touching another cell.

Wikipedia describes this as a logic puzzle and gives more elaborate rules, particularly about the possibility that 2 or more given numbers could belong to the same pentomino. Solution methods are also offered.

As this is a fairly popular puzzle in its own right, there are a variety of Websites that offer Fillomino:

  • Puzzle Club a British Site offers Many Math, Number, Logic, and Word Puzzles in addition to Fillomino. Registration is 10 Pounds/Year
  • Vegard Hanssen’s Fillomino Puzzles, which has more than 16,000 Puzzles in its database. Mr. Hanssen is a perl programming language afficionado, See his perl scripts for generating his name(s).
  • provides 8x8s, 12×12 and 16×16 size grids for their daily Fillomino puzzles.
  • Simon Tatham has a similarly named puzzle called Filling on his website.
  • Finally, has an interesting discussion about Fillomino Skyscrapers which is a mashup of Fillomino and what I called buildings. The numbers on the outside are clues to how many “buildings” can be viewed from that location. Higher valued numbers block lower valued numbers, but offer interesting clues about the composition of the row or column. See my Sudoku Buildings Cartoon posted last July 15, 2007.

Get your fill of Fillomino! (but take your time.)

Signal Pennant Sudoku

Sunday, March 16th, 2008

Signal Pennant Sudoku

The use of flags and pennants as communications has intrigued me. According to the Sea Flags web site, Athenian (Greek) ships were first known to signal each other with brightly colored flags. Time passed and Navies of various European countries began to devise more sophisticated communication using semaphores and flaghoists after 1750.

The current situation is depicted in the International Code of Signals and in particular, pennants representing the digits one through nine are shown in the cartoon.

It’s an easy leap to create a sudoku puzzle using these pennants as stand-ins for the normal digits. You may do this puzzle calmly and in a room that has been becalmed as well.

Time Change Sudoku

Sunday, March 9th, 2008

Time Change Sudoku

In most of the United States (But not Arizona nor Hawaii), Daylight Saving Time began early this morning, March 9. I find out how many clocks I’m governed by when I do this twice-yearly ritual. Occasionally, the clocks I missed last fall are telling accurate time now and they stay unperturbed.

I found an interesting Web Site called describing Daylight Saving Time and which uses a kind of a mind-map (that they call clouds or nodes) to display information, in lieu of powerpoint-like slides. For this, you must let go of outlines and hierarchy.

Wikipedia has a colored map of use and abstinence of DST (or Summer Time) Worldwide.

To honor the induced chaos of time changes, I’ve created a Sudoku Puzzle which uses analog clock faces. Take your time.

Usually at this time of year, the Yearly Sudoku World Championship announces itself. Based on a cursory web search, The 2008 Sudoku World Championship will be held on April 14-17, 2008 in Goa, India on the West Coast in the Konkan region and bordering the Arabian Sea.

Registration apparently started March 8, 2008. This year publicity is currently sparse, so much information emanates from a Technical Blog called Revisit it during the next month, for further details.

Scrabulous On Sudoku

Monday, March 3rd, 2008

Scrabulous On Sudoku

Based on the March 2, 2008 New York Times Article about the dilemmas posed by Scrabulous™, an online game invented by Rajat and Jayant Agarwalla, from Kolkata, India, this cartoon was born.

The online game appears to be an intimate embrace of Scrabble™, currently physically sold and distributed by Hasbro, Inc. and Mattel Inc., who together divide up the World Rights to sell the game.

As is becoming clearer in the 21st century, having an online version stimulates sales of physical (original) versions. By squelching the online versions, these companies risk severe sales reductions due to bad publicity and a collective vow to boycott those company products. By not squelching the online versions, the companies must adapt (like the music and movie industries are [not] doing) or go out of business anyway. Choose wisely.

I thought it would be amusing to mashup Sudoku with Scrabulous. You can play it with either game goal in mind, but pursuing both will no doubt mentally bifurcate you, which is a serious condition, sometimes leading to split personalities.