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




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.



About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.
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