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Sudoku Puzzle Challenge–May 2016


Are you ready for another Sudoku challenge this month?

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

DAN’S 8-STEP APPROACH TO SOLVING 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 …

2015/16 TI LIFE SUDOKU ARTIC

LES

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

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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

This eight step approach will solve virtually all published Sudoku puzzles. In my Sudoku experiences, this approach has yet to fail. You may want to print this entire article to do the puzzles and have a “portable” guide to the solution if needed.

PUZZLE #7 

In keeping with the theme of the last 3 months, puzzle #7 can be solved with Steps 1-5, and puzzle #8 will require Step 6 assistance. Please remember to process obvious pairs in the puzzle preparation phase.

Puzzle 7 1_1a

Puzzle # 7

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

Puzzle 7_2

PUZZLE #7, THRU PUZZLE PREPARATION

If your puzzle does not look like the one above, you probably missed something in Puzzle Preparation. If so, and you do not find the clue, then I suggest you continue with the above to see if you can reach a conclusion to Puzzle #7:

Steps to complete Puzzle #7 :

  • C5R3 (Column 5, Row 3), C7R3 & C8R3 present a Triplet 169, so you may eliminate a 9 as an option from C6R3.
  • C8R3 & C9R2 facilitate a Turbo 9, eliminating 9 as an option from C4R5.
  • C1R6 & C3R6 form an Interaction, eliminating 7 as an option from C1R4 & C2R4. Then C1R6 = 7.
  • C2R4 & C2R9 form a 29 Pair, eliminating 2 as an option from C2R1 & C2R7.
  • C3R2, C3R6 & C3R8 form a Triplet 369. Eliminate a 3 & 6 from C3R1 and a 6 from C3R7.
  • C3R2, C3R8, C4R2 & C4R8 form an X-Wing, eliminating a 6 from C7R2. Then C7R2 = 7.

From this point the puzzle is easily solved.

Puzzle 7_3

PUZZLE #7 COMPLETE

In previous 2016 issues of TI LIFE Step 6, “DAN’S YES-NO CHALLENGE” was used to solve puzzles #2, 4 & 6. It is a fun technique and I would strongly suggest reading the 16 pages devoted to this technique in my book. It explains in detail how to detect this Technique when working on your Sudoku puzzles.

As mentioned earlier, you may use this technique to finish Puzzle #8, once you have exhausted Steps 1-5. See if you can find three Step 6 techniques that will break the puzzle!

Puzzle 8_1

PUZZLE # 8

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

Puzzle 8_2

PUZZLE #8, THROUGH PUZZLE PREPARATION

Again, if your puzzle does not look like the one above, you probably missed something in Puzzle Preparation.

If so, and you do not find the clue, then I suggest you continue with the above to see if you can reach a conclusion to Puzzle #8.

Steps to complete Puzzle #8:

C7R8, C9R1 & C9R8 form an XYZ-Wing, eliminating 6 from C9R7.

C8R3 & C8R7 create a Step 6 opportunity, eliminating a 6 from C1R9. (Either C8R3 or C8R7 is a 6 in column 8. If C8R3=6, then C2R3 & C3R3 are not a 6; then C1R1 = 6; then C1R9 is not a 6. If C8R7=6, then C4R7 is not a 6, then C4R9=6, then C1R9 is not a 6. So regardless if C8R3 or C8R7 is a 6, C1R9 is not a 6, and the 6 can be eliminated as an option from C1R9.)

C3R2 & C3R9 create a Step 6 opportunity, eliminating a 9 from C9R7.

C8R2 & C8R7 create a Step 6 opportunity, eliminating 9 from C1R9; then C1R9=1.

C2R3 & C3R3 create an Interaction 6, eliminating 6 as an option in C7R3 & C8R3.

C8R3 & C8R4 form a pair 14; then C8R2=9.

The puzzle is easily solved at this point.

Puzzle 8_3

PUZZLE #8 COMPLETE

If you have any questions, comments, or suggestions to improve this monthly article, I would really like to hear from you. You can post on this TI Life issue, or contact me directly at djlsuniverse@yahoo.com.

May the gentle winds of Sudoku be at your back!

By Dan LeKander, Wellesley Island, NY

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 three locations online, (djlsuniverse.com, amazon.com and ebay.com).

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

 

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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