Erasable Games specializes in white board products designed to make games like Sudoku easy and fun.

## Erasable Games Weblog

(Sudoku in words and pictures)

## Entries tagged with 'Geometry'

### Crop Circles Sudoku

Monday, December 31st, 2007

So as I was waiting for my Toyota Matrix (dashboard view) to be serviced, I was reading fairly metaphysical Book called 2012, The Return of Quetzalcoatl, by Daniel Pinchbeck. who spends some time discussing people who take crop circles seriously. Note the cover art.

It occurred to me that because there have been so many instances of crop circle manifestations, especially in the United Kingdom, that the sheer precision and incuse designs would provide clear examples of geometric one-to-one correspondences with the first 9 digits. Clearly, if aliens are trying to communicate with humanity, using geometric art as the communication medium offers a common reality that beats the symbols we use for our number system(s).

I am indebted to Lucy Pringle’s Crop Circle Photographic Library for these images. Her collection of photographs of these mysterious, aerial views of crops bent artistically is extraordinary.

She is a leading researcher and author of 3 books on the subject — Crop Circles: Greatest Mystery of Modern Times (2000), Crop Circles (2004), and her latest Crop Circles: Art in the Landscape (2007).

I hope this cartoon helps to publicize her efforts to bring serious attention to all humanity (who’s interested) in this curiously ignored, yet significant messaging system between an unknown entity or entities and humanity.

I wish a happy new year to all, worldwide. Whenever you’re ready.

### Do-Sum-Oh (Squiggly) Sudoku

Sunday, December 16th, 2007

I came upon Squiggly Sudoku puzzles at Bob Harris’ bumblebeagle.org site. This variant emphasizes the distortion of the 3×3 squares into irregular geometric shapes also containing 9 squares each. His site contains a proof that n-1 starting numbers (or letters) Du-Sum-Oh (Squiggly) exists uniquely for any n x n sized puzzle. The puzzle above has n starting letters for a 9 x 9 sized puzzle, so it should be easier.

Bob Harris offers various sized puzzles on his website and has published a book called Squiggly Sudoku (Sudoku With A Twist) containing 120 various sized puzzles.

He also provides a useful tutorial about how to solve these puzzles. He cites the Big (and Little) Law of Leftovers. The Big Law of Leftovers: Wherever a group of regions overlaps some rows or columns, the parts outside the overlap (the leftovers) have to be the same.

Another pair of authors, Gideon Greenspan and Rachel Lee provide another book of 200 puzzles, also called Squiggly Sudoku However, of these 200, only 144 are Squiggly Sudoku puzzles, the rest are either classic Sudoku (40) or Samarai Sudoku (16) of various levels of difficulty. They also maintain a Website called Web Sudoku with daily (printable) squiggle and other puzzles.

Another Web Site that provide Squiggly Sudokus is Daily Sudoku By Sam Griffiths-Jones. He is also responsible for several sudoku books, including one for kids and an advanced puzzle book. He also sells Electronic Books of puzzles including Squiggly Sudoku puzzles.

This cartoon is comparable to the cartoon I published last June 2, 2007, called Jigsaw Sudoku where numbers instead of letters were used.

While Sudoku puzzle solving is a great boon to maintaining/increasing cognitive brain function, some may eventually get bored with it, hence the invention of Sudoku variants. The fact that boredom sets in to a previously stimulating activity is just human nature. Similarly doing the same physical exercise initially builds muscle tissue but after a while it no longer does.

There is an indication (See Carved in Sand: When Attention Fails and Memory Fades in Midlife by Cathryn Jakobson Ramin, for example) that our brains, when exposed to greater stimulation have a greater number of healthy nerve cells and stronger connections between them. The act of doing puzzles for example, requires continuing novelty to provide sustained stimulation (and interest). The practical consequence of this is to keep our brains agile throughout our entire lives and not have it turn to oatmeal before we’re ready.

### Jigsaw Sudoku

Saturday, June 2nd, 2007

Jigsaw Sudoku relaxes the requirement of square blocks as in regular Sudoku puzzles. Instead, non-square rectilinear shapes made out of contiguous cells are used instead. The requirement that rows and columns each have unique digits is still true, however.

Some sites that offer Jigsaw Sudoku puzzles include: Puzzle Club, Competition Jigsaw Sudoku and a site offering Sudoku Variants And Other Number Placements.

### Geometric Sudoku

Saturday, April 28th, 2007

A mapping of Geometric Shapes For Sudoku Purposes. Each n-gon shape contains the number of sides corresponding to its units digit.