Rod’S Sudoku Tutorial

Copyright © 2017 Rodney L. Wagner.

All rights reserved. No part of this book may be used or reproduced by any means, graphic, electronic, or mechanical, including photocopying, recording, taping or by any information storage retrieval system without the written permission of the author except in the case of brief quotations embodied in critical articles and reviews.

This book is a work of non-fiction. Unless otherwise noted, the author and the publisher make no explicit guarantees as to the accuracy of the information contained in this book and in some cases, names of people and places have been altered to protect their privacy.

Sample puzzles 1, 2, and 3 are reproduced from Dell Original Sudoku, November 2016, puzzles 69, 44, and 77. Used with permission of Dell Publications.

Sample puzzle 4 (used in part 3) was reproduced from Dell Original Sudoku, magazine dated November 2016, puzzle number 203. Used with permission of Dell Publications.

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ISBN: 978-1-4808-5405-5 (sc)

ISBN: 978-1-4808-5404-8 (e)

Library of Congress Control Number: 2017917041

Archway Publishing rev. date: 12/11/2017

My sister-in-law, Alice, by chance saw that I worked sudoku. She asked if I could teach her my techniques.

I said yes and started an outline so I would be sure to cover most of the essentials and techniques I use to solve puzzles. Later I began adding details and compiled examples, which eventually became this tutorial.

My wife, Sharon, encouraged me during the earlier periods of writing my outline and notes. Then, when the tutorial was finished, she greatly encouraged me to publish the book.

And so I have.

Thank you, Alice and Sharon,

and to you both, I dedicate this book

and all my efforts!

CONTENTS

Welcome Letter

Introduction

Part 1—The Beginnings

Technique 1:   Horizontal Section Group Scans

Technique 2:   Vertical Section Group Scans

Technique 3:   Repeating Techniques 1 and 2

Technique 4:   Working Single-Digit Occurrences

Part 2—Intermediate Level

Technique 5:   Solving One and Two Empty Cells

Part 3—Advanced Procedures

Technique 6:   Determining Penciled Candidate Lists

Technique 7:   Solving the Candidate Lists

Conclusion

Appendix

Special Thanks

WELCOME LETTER

June 2017

Dear Alice (and all other sudoku enthusiasts):

I am thrilled you have been introduced to sudoku and desire to solve the puzzles. Sudoku is fun, challenging, and sometimes frustratingly difficult. I hope you will find this book, Rod’s Sudoku Tutorial, helpful, whether you are a novice or have a moderate amount of experience and are seeking to improve your skills.

Ed introduced me to sudoku in the summer of 2005, and I have probably worked over 2,500 puzzles since then and continue to do so. I was told only the three basic rules of sudoku and was shown a copy of a newsstand sudoku puzzles magazine. I purchased a copy, read the introduction, and went to work at the beginning, where the easy-rated puzzles are located. I worked nearly 400 easy puzzles before I even looked at the medium puzzles. I have now successfully solved scores of hard puzzles and even some extreme puzzles.

I have often made blank grids (see Illustration 13, Appendix), filled in the givens in ink, and reworked many puzzles (in pencil) after I had worn holes in the original copy from writing and then erasing in them. (I have done this so many times I can’t remember.)

Go for it. If you get stuck, don’t get frustrated; set that puzzle aside for some time, and try a different one.

Above all, enjoy sudoku!

/s/ Rodney L. Wagner

INTRODUCTION

These tutorial techniques are the result of my personal experience after I was introduced to sudoku and had read the brief introductions found in the front of sudoku publications like the ones published by Dell and Kappa. There is no magic! Any technique is primarily simple logic applied to the basic rules of sudoku. You simply have to find the right digit to enter into an empty cell or eliminate the digits that cannot be entered into an empty cell.

In this tutorial, I attempt to give instructions and show by example how to solve an entire puzzle, step by step, from beginning to end. I sequentially use each digit 1 through 9 in each technique. With this method, I know when I am done and am confident I have been complete and exhaustive; I have not missed any possible play. (But I always check my work and the answers anyway.) From these instructions and examples, I hope you will be able to gain enough information to go on and solve many puzzles on your own.

Before you start a sudoku puzzle, orient yourself to the puzzle. (See illustration 1.) The puzzle is a large square containing nine rows and nine columns with each containing nine small squares. The total puzzle is subdivided into nine square sections with each section consisting of three contiguous rows and three contiguous columns. These sections are usually indicated by heavier lines. All the small squares formed by the intersection of a row and a column are called cells. To identify each cell uniquely, it will be referenced (in this tutorial and elsewhere) by section, row, and column (e.g., S5R7C4). Further, each section, row, and column may be referenced individually or in combination (e.g., S3; R9; C5; S5R6, or S2R2 and 3; S7C7 and 8; and so on). Every puzzle comes with a certain number of digits with a varying number of occurrences already placed in various cells in the puzzle; these are given to you as a starting point, and thus they are called givens.

The objective is for you to find the right digit for each and every one of the empty cells. When the puzzle is completely solved, each row, each column, and each section will have one and only one occurrence of each digit 1 through 9. (This may seem a restatement of the three basic rules, but it is of utmost