Sudoku Basics
About sudokuSudoku is a number placement puzzle that challenges your logic skills and patience. It consists of a series of grids with the standard size of 9x9 which houses nine smaller 3x3 grids. The goal of this game is to place a number from 1- 9 in each of the grid boxes. Each number 1 - 9 must only appear once in each column, once in each row and once in each smaller 3 x 3 grids. Each puzzle provides a partially completed grid. The puzzle's name is short for "Sūji wa dokushin ni kagiru" which means "the numbers must be single" or "the number may only appear once". In the US, it may also be called "Nanpure", short for "Number Place"
History of Sudoku
The origin and history of sudoku
The name "Sudoku" might lead you to conclude that this game came from
Japan because of it's Japanese sounding name but the game "Sudoko"
and it's development reveals that unlike many games that orginate
from one culture and are then adapted and absorbed by others, it's
history reveals that this game represents the best in cross-cultural
creation.
"Su" in Japanese means numbers and "Doku" refers to the single place
on the puzzle board that each number can fit into. The origins of
this game is traced back to the Europeans and the Americans. During
the 18th century, a Swiss mathematician Leonhard Euler developed a
concept of "Latin Square" where numbers in a grid can only appear
once, across and up and down. During the late 1970, a US magazine
called Dell Magazine published what we now call Sudoku puzzles using
the mathematicians concept with a 9 by 9 square grid. The puzzle was
called Number Place and was further developed by independent puzzle
maker, Howard Garnes.
During the mid-1980's, Mr. Maki Kaju, the president of Japanese
puzzle giant Nikoli, Inc. encouraged the company to come up with a
version of the puzzle that eventually became a hit when it got
published. It was Kaju's company that gave the game it's current name
and revolutionized the puzzle by restricting the number of revealed
or given numbers to 30 and having them appear symmetrically. From
then on, it became a permanent fixture in daily magazine and
newspapers in Japan and later on was featured by a London based
newspaper, The Times as a daily puzzle. The first puzzle came out of
the newspaper on November 12, 2004 and a few months after some
British newspapers began to feature their own Sudoku puzzles.
The breakthrough of the puzzle in Europe began when a retired
HongKong judge who originally hails from New Zealand, Wayne Gould,
came across a Sudoku puzzle in a Japanese bookshop in 1997. He was
very fond of the game that he spent years coming up with a computer
program that would generate the puzzle. In fall 2004, he was able to
persuade The Times to start publishing Sudoku puzzles using the
software that he developed.
The growing popularity of the puzzle crossed ocean and landed on the
United States shores summer of 2005. US newspapers such as the New
York Post, the San Francisco Chronicle and USA Today offered Sudoku
puzzles to their audience by September 2005. Sudoku puzzles have
increased so much in fame that US print media have published Sodoku
puzzles as much as the crossword puzzles have been put out.
As of today, the puzzle has evolved and several adaptations have been
released. Grids with sizes 4x4, 5x5,6x6 and 7x7 have been released to
fit to the needs of different audiences. Nikoli even created puzzle
grids that are sized 16x16 and 25x25 for those who are addicted to
the game. Mobile phone and computer software manufacturers even have
included the game in their products. There are variations of the
puzzle that use letters and symbols instead of the usual numbers.
No one can tell where this rapidly growing game would lead to in the
future but one thing is for sure, the Sudoku is a fun and challenging
game that would always tickle the fancy of every person who plays the
puzzle. It can help hone the logical, mathematic and deductive skills
of everyone no matter his age, culture or sex.
How to solve a sudoku
Sudoku tactics
The strategy in solving a Sudoku puzzle may compose of a combination
of these process: scanning, marking up and analyzing. And every kind
of strategy can be grouped in two, by difficulty and by family.
Scanning is done at the outset and throughout the solution. It
consists of two techniques: Cross-hatching and Counting 1-9 in
regions, rows, and columns to identify missing numbers. Puzzles that
are easily solved using this method are classified as "easy"; the
more challenging puzzles are not readily solved by scanning.
When scanning stops because no further numerals can be discovered,
making it necessary to use logical analysis. Marking up can be useful
in this case, where the analysis is guided by marked candidate
numerals in the blank cells. There two kinds of marking up: dot
notation and subscript notation.
Another strategy in solving the puzzle is through Analysis which has
two main approaches to analysis the "candidate elimination" and
"what-if" or the trial and error way.
Some categorize strategies by family: Basic Strategies like naked
pairs, pointing pairs and hidden triples. Chaining Strategies include
the Y-wing, Multi-Colouring, Forcing Chains and more. Exotic
Strategies include the Pattern Overlay method, Sue-de-Coq and Aligned
Pair Exclusion. Other family types are: Jigsaw Strategies, Killer
Strategies, Sudoku X Strategies and Uniqueness Strategies.