Sunday, April 05, 2009

Rules in Playing Sudoku

Sudoku Jigsaw PuzzleImage by r.j.wagner via Flickr

If you’re fond of playing puzzles, solving math problems, and think logic reasoning you can actually combine them all in playing the Sudoku puzzle.

For you to know, sudoku was first seen in a magazine published in New York in the late 70’s by specialist puzzle publisher Dell Magazines under the name of Number Place. “Su” means number in Japanese, and “doku” means the single place on the puzzle board so that each numeral can be fitted into. Although its name sounds like Japanese, its origins came from Europe and America in which the game shows the very best in thinking and reasoning. Sudoku initially caught Japan in 1986 and gained international prominence in 2005. Unlike many other games that were known within the span of time, nothing can beat Sudoku’s challenge.

Sudoku, commonly known as the Number Place, is a logic type placement puzzle. The aim of the puzzle is to place numerical digits from 1 to 9 in each cell of a 9x9 grids that is made up of 3x3 subgrids or regions. To start playing the game, you are given in some empty cells numerals which are called “givens”. The goal of the puzzle is to put the numbers 1-9 to which it must contain only once in each subgrids, rows, and columns.

Basic rules

Rules in playing the game are very simple:

• Sudoku is played over a 9x9 grid, divided in 3x3 subgrid.
• Begins the play with some given numerals from 1-9 that are placed in grid cells.
• A number can only appear once on each row.
• A numeral can only appear once on each column.
• Digit can only appear once on each region.

Now you finally know the basic rules in playing the game, but you’re really just starting the process of making solutions to how finish the game. There are some solutions methods that can help you and these are:

• Scanning- it can be performed from the very beginning and throughout the solution process. Scanning basically has two techniques, first the cross-hatching. Cross-hatching technique can identify which line in a particular region may contain a digit that can be eliminated. The second is counting the region, columns and rows in identifying missing numbers. Counting based upon the last digit discovered may actually speed up the corresponding search.

• Marking Up- the candidate numbers are simply written in subscript in the cell. The disadvantage of this is that some first puzzles are printed in magazines and newspapers which are usually small to accommodate many preferred numbers. Unlike to some newly designed Sudoku game board, all inputs are done electronically. You can also use a pattern of dots within the cell, wherein the position of the dot corresponds a number from 1-9. Dot notation can be an advantage to a sudoku that is printed in paper. In playing sudoku in print, using a sharp pencil with an eraser is highly recommended.

• By Analysis- you can approach the game by either “candidate elimination or “what if”. In candidate elimination, numerals from one or more cells are eliminated and leaving just one choice. After each answer is placed, another scan can be done. You can check to see the effect of the contingencies. In “what if” approach, a cell can be placed with two candidate numbers then a guess should be made.

Difficulty ratings

Published Sudoku puzzles are ranked depending of rate of difficulty. For you to understand, the numbers that are given has nothing to do on a puzzle’s difficulty. A sudoku puzzle with less number of givens may be very easy for you to solve. A sudoku puzzle with more number of givens can still be very difficult for you to solve as the difficulty rate of the puzzle depends on the relevance and positioning of the given numerals rather than the number of given placed in the grids.

Computer solvers find the range of difficulties for a human to find a certain solution, based on the complexity of the techniques needed. For in this kind of estimation allows publishers to take Sudoku puzzles to be very demanding. Some sort of publications rate their Sudoku puzzles into four levels are “easy”, “intermediate”, “hard”, and “challenging” are set.

So, by playing the “fastest growing puzzle in the world”, you can be sure to challenge your way of thinking and have fun in the process.

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