Pitkow’s Super GMs


Here I review five preselected puzzles from Xaq Pitkow’s 25 Super Grand Master collection of 50 in his Sudoku, Vol. 5.  Only one of five clearly ranks as extreme, above the spotty Grand Master collection just reviewed.  I detail this one, SGM  10 ,  to point out the LPO support of Medusa coloring.  Two  other advanced level SGM puzzles are highlighted in the next post, as examples of advanced coloring.

I selected only five for review, not wanting to cover so much of the limited collection. The review table tells the story:

SGM review tableThe basic trace of SGM 10 was simple enough for the 1-D format. Yes , that’s a naked quad in c4.

SGM 10 basic trace

SGM 10 wingI’ll skip the usual line marked grid, because it’s all there in this one.  The 358 wing is definitely advanced level, requiring a forcing chain to attach the 35 wing.

Nothing further on the bv scan or X-panel. A blue/green cluster was started, but the clouds of 3- and 8-candidates hems it in.

 

This imbalance leaves six numbers sparse enough to be eligible for LPO conflict analysis, but ahead of that in the order of battle is a second cluster .  The imbalance also creates a wealth of slinks.

SGM 10 clashThe second cluster spreads into the 9 patterns, and a 3-candidate is trapped.

More decisively, the 9 slinks deliver a quick rebuttal of blue.  Blue implies orange and not orange.  You can’t get away with that.

But wait. Even without blue, there is that 9 bv partner that is asserting the same thing. It must go as well.

SGM 10 remote sixWhen the debris is cleared, the candidate imbalance rewards us with the longest effective remote pair I’ve ever encountered.  Six 38 bv, the end bv proving orange.

You can see the rest from here.  The naked pair NEr2np34 solves one end, and the 38 pathways are all solved. The 34 ducks are also on this row.  Its over.

 

SGM 20The review table reports plenty of action in SGM 20. Want the thrill of discovery for yourself before I show it off next time?

Go for it!

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About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.
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