Sudoku Essay

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If you walk into any book store you are bound to find entire shelves completely comprised with books that have 100+ different Sudoku puzzles for the reader to solve. Throughout the past 10 years Sudoku has become an internationally known puzzle game reaching the same amount if not surpassing in popularity as the crossword puzzle. In this paper I will explore how to determine how many fundamentally different completed Sudoku puzzles (known as Sudoku Squares) exist. In order to do this I will first give a brief history of where Sudoku puzzles originated from, then I will show how to determine how many Sudoku squares exist which will lead me into determining how many of the Sudoku squares that exist are fundamentally different from each other.
Latin Squares

Sudoku puzzles originated from Latin Squares which have been studied by mathematicians for centuries. A Latin Square of order n is an square with n rows and n columns where each row and column contain each of the n symbols appears exactly once. The following below are some examples.
Those who are adept in Sudoku puzzles will notice that a Sudoku puzzle is a 9x9 Latin Square without the 3x3 block criteria.

Counting Sudoku Squares
Shidoku Squares
At Barnes & Noble there is an entire section full of Sudoku puzzles. They include books like Treacherous Sudoku, Pocket Sudoku, Killer Sudoku, and Enslaved by Sudoku. With the amount of different Sudoku books, one question that I had was how many different Sudoku squares can there be? Since there are so many restrictions on what makes a Sudoku square, we are going to first consider Shidoku squares as they are going to be easier to visualize. A Shidoku square is a 4x4 square that follows the same restrictions as Sud...

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...allowed them to use Burnside’s Lemma and they discovered (56(0)+48(2)+4(6)+6(8)+4(10)+1(12))/128=256/128=2, where 56 of the transformations didn’t fix any squares and 1 transformation (the identity transformation) fixed 12 squares. Thus, there are only two fundamentally different Shidoku squares.
Now, there is also a less complicated way of determining how many fundamentally different Shidoku squares exist….pg 80, not sure I want to take time to explain this….
Sudoku Squares
Earlier, we determined that there are approximately 6.67 sextillion different valid Sudoku squares, our task is to use the six possible transformations (stated earlier) and Burnside’s Lemma to determine how many fundamentally different Sudoku squares exist. There are six basic transformations that can be applied to a Sudoku square, but we can combine multiple transformations to achieve a

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