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Sudoku Puzzle Challenge-September 2016


Both puzzles in this month’s article will definitely expand your Sudoku horizons!

First, we will revisit the approach, as discussed in Dan’s first six TI LIFE articles …

 

DAN’S 8 STEP APPROACH TO SOLVING ALL SUDOKU PUZZLES

Once you have completed the puzzle to the extent that you have filled in all obvious answers and have written all potential options across the top of the unsolved cells (PUZZLE PREPARATION), Dan recommends the following steps to complete the puzzle.

See TI Life Puzzle Preparation:

Step 1:  Sudoku Pairs, Triplets and Quads – September, 2015

Step 2:  Turbos & Interaction – October, 2015

Step 3:  Sudoku Gordonian Rectangles and Polygons – November, 2015

Step 4:  XY-Wings & XYZ Wings – December, 2015

Step 5:  X-Wings – January, 2016

________________

Step 6:  DAN’S YES/NO CHALLENGE

Step 7:  DAN’S CLOSE RELATIONSHIP CHALLENGE

Step 8:  AN EXPANSION OF STEP 7

Steps 1-5 are relatively common techniques and are explained in the TI LIFE articles per above. Steps 6-8 are covered in detail in Dan’s book.

Also see Sudoku Puzzle Challenge… February 2016, Sudoku Puzzle Challenge–March 2016, Sudoku Puzzle Challenge–April 2016, May 2016June 2016, July 2016 and August 2016.

Puzzle 15 blank

Puzzle #15

If you need assistance, Puzzle Preparation should result in the puzzle looking like below:

Puzzle 15 through prep

Puzzle #15: Through Puzzle Preparation

Steps to complete Puzzle #15

Actually, we should say “Step”, as it is easily solved by recognizing a Step 1 Triplet. You will find three cells in row 8 have a monopoly on the numbers 3, 4 & 6. Therefore you can eliminate the 3,4,6 from the other cells in row 8. Then C9R7=4 (cell in column 9, row 7), eliminating the 4 from other cells in row 7. C2R7 and C3R7 now have options 2,6. Therefore C3R8=4, C5R8=3, C6R8=6. C5R1=8. C3R1=2. & C3R7=6. From this point you can easily solve the puzzle. This illustrates how identifying Pairs, Triplets and Quads can enhance your game.

By the way, did you notice the Triplet in column 5 that you did not even need?

Puzzle 15 complete

Puzzle #15: Complete

PUZZLE #16 … Hint: Make this a Step 6 fun day! Please remember to process obvious pairs in the puzzle preparation phase.

Puzzle 16 blank

Puzzle #16

If you need assistance, Puzzle Preparation should result in the puzzle looking like below:

Puzzle 16 through prep

Puzzle #16: Through Puzzle Preparation

Steps to complete Puzzle #16

Step 2 … C9R2 & C9R3 form an Interaction, eliminating an 8 from C9R7.

Step 2 … C1R6 & C2R6 form an Interaction, eliminating a 5 from C7R6.

Step 6 … In box 6 there exist only two cells that contain a 2 as an option. Therefore one of these two cells must be a 2. Time for Dan’s Yes-No Challenge! As we perform this exercise we will simply say “yes” if a cell is a 2, and “no” if a cell is not a 2. So, first we will assume C8R5 is yes, then C8R1, C8R2 & C8R3 are no. Next we will assume C7R6 is yes. Then C4R6 & C5R6 are no. Then C5R5 is yes. Then C5R3 & C5R2 are no. Then C4R1 is yes. Then C8R1 is no, and C1R1 is no. Then C1R3 is yes. Then C8R3 is no. So regardless of which cell in box 6 is a 2, C8R1 & C8R3 are not a 2, and the 2 can be eliminated from those two cells. Then C8R3=7.

Let’s do a little more magic. If C7R6 is yes, then C5R6 is no. If C8R5 is yes, then C8R2 is no, then C7R1 is yes, then C4R1 is no, then either C5R2 or C5R3 is yes, then C5R6 is no. You may eliminate a 2 as an option from C5R6.

From this point C9R7=7, C2R8=7, C2R9=6. Using Interactions and a Triplet, the puzzle can easily be solved from here.

This was a bit more of a complex Step 6. This is why I provide “players” with the book, so you can place a player on each unsolved cell in the puzzle that contains a 2. This helps to easily identify the yes’s and no’s. You can actually use any type of a marker, as long as it fits within a cell grid.

Puzzle 16 complete

Puzzle #16: Complete

Do you have any suggestions for future articles? You can post on this TI Life issue, or contact me directly at my e-mail address … djlsuniverse@yahoo.com.

Editor’s note:

Do you tackle a Sudoku on your cottage veranda, sailboat cockpit, or at a campsite?  TI Life is taking full advantage of Dan LeKander, from Wellesley Island, who is a Sudoku expert and author of “3 Advanced Sudoku Techniques – That Will Change Your Game Forever!”

In January 2016, we published a final article in his series – but many of us enjoy using “Dan’s Steps”, so when he asked if we would like a puzzle to solve every month … this editor said an enthusiastic… Yes, please!

I suggest you try this relatively easy puzzle and that you also purchase Dan’s book, “3 Advanced Sudoku Techniques, That Will Change Your Game Forever!”

Most importantly, I ask that you leave comments on any part of his series and throughout the coming year.  Remember when your teacher said –  no such thing as a silly question – as we can all learn together.

Dan’s book is available at two locations online, djlsuniverse.com,amazon.com and on ebay.com.

Purchase of a book includes a 50-page blank grid pad, 33 black and two green tokens, to assist with Step 6.…

NOTE:  Dan has asked if you have an suggestions?  My first thought is some sort of end-of-year competition.  Send us your thoughts and  I will find a suitable prize for the one we choose!

(And thanks to Dan… what a lot of work he puts into our TI Life articles.  And another thank you goes to Bill Stallan, who proof reads the content each month!)

Thank you for your interest. May the gentle winds of Sudoku be at your back!

Dan LeKander

Dan LeKander and his wife, Peggy, have been seasonal residents of Fineview, on Wellesley Island, NY, since 1983.  In addition to being a Sudoku addict, Dan explores the 1000 Islands to enjoy the wildlife, beauty and of course, Catch-and Release bass fishing.

[See Jessy Kahn’s Book Review, “3 Advanced Sudoku Techniques…” by Dan LeKander, June issue of TI Life.]

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Kristen Taylor
Comment by: Kristen Taylor
Left at: 9:42 AM Friday, September 16, 2016
Brilliant as always!

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