A Colorful Ending to World’s Hardest 200


Here we translate into sysudokie notation the XY-chains and coloring that drag off World’s Hardest Sudoku 200, to its sudowiki solver solution. Hopefully you were better able to arrive at your own solution.

First are the new developments on the bv map, where a XY-chain ANL triggers boxline Nr4, which triggers boxline SEr9.

 

 

 

 

 

 

This brings in a naked triple and more XY railway, a 2 eliminating ANL, .  .  .

 

 

 

 

 

 

 

.  .  . and a 3 eliminating ANL.

The follow up

NE2=>NW2=>

NE3=>SE5

 

opens it up for another cluster, and r5:

not(blue and orange) => green or red

sends us looking for a bridge elimination.

Instead, yet another XY-chain expands both clusters, to trap 6r4c5  and wrap orange on r3.

Red leaves a single blue 1 on r4, and there’s nothing left to say.

Except that the review continues, without solver assistance, and with Worlds Hardest 36, with ratings falling to 0.91.

 

 

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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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