It’s the Bypass In Hard Sudoku v1 145


I had Will Shortz’Hard Sudoku v.1 145 collapsing in box marking, showing that every phase of Sysudoku Basic is actively solving, not just accumulating candidates for advanced methods later. But in process of writing this up, I discovered that the bypass had found a way to keep its collapse going.

Here is the basic trace.

I had missed that the chute 3-fill Cr4[158] leaves the c4 naked pair 69, that also completes the r8 naked pair 69, that gives SW8 and two more clues in the SW box.

It works, because subset pencil marks are posted in the slink marking bypass.

 

 

Next,  the review continues with Hard Sudoku v1  155.

On the advanced front, the review of KrazyDad’s Insane collection is being updated, for pattern analysis examples in the Guide. So far updates of July 2013 on Insane 415 and 425 are posted.

The AIC Hinges page of the Guide is being revised to include the AIC boomerang, a type of elimination ANL with its own spotting technique.

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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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