A Little Harder Ardson v2. 358


Next to last, and getting beyond the XY railway, is A.D. Ardson Very Hard, v.2 358. Here is the basic trace, including an X-wing in the close of line marking.

The column 6-wing  was found in line marking closure, when the column 2 6-slink matched the column 9 6-slink from the bypass:

Persistence results in an XY elimination that seems less decisive than it turns out to be.

 

 

 

 

 

 

 

Moving on to the X-panels, the first one yields a 1-chain ANL (almost nice loop), and the N box removals create a new slink and a slink elimination in the South box. Elsewhere, this is described as a type of box/line interaction.

 

 

 

More decisive action comes on the 5-panel.  My habit is to look for fish before X-chains on a panel. Here I get a kraken 5-wing, where one of the finned fish targets sees the fin via a five link 5-chain. Simpler and better is the 5-chain removing the kraken victim and one more.

 

 

 

 

The trace runs until there are only two cells of three values holding off a BUG.

 

 

 

Coloring brings an easy wrap of green in r9, and its done.

The review of A.D. Ardson’s Very Hard v.2 closes next time with Ardv2 398. It is the most challenging of the puzzles pre-selected for the review.

Following that, we’ll double back on my miscopied version of Ardv2 38. Is your comment ready?

 

 

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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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