Ardson Very Hard v.2 198 and 238


The review of A.D. Ardson Very Hard Puzzles v.2 continues with Ardv2 198 and 238. The sysudokie resolution to 198 is a rerun of 158, but 238 is a classic remote pair example.

Ardv2 198 barely escapes the bypass, but still manages to get to the bv scan.

 

 

 

 

 

 

It arrives with a large, well connected bv field, which promises an extensive XY Railway.  The first XY  I happen upon, . . .

 

 

 

 

 

 

proves to be decisive.

That makes Ardv2 198 very much like Ardv2 158.

 

 

 

The next review puzzle, Ardv2 238, follows an entirely different advanced sysudokie path. Basic solving leads to .  .  .

 

 

. . . a grid dominated by 78 bv and 578 cells.  The easiest prey in this patch is the remote pair chains.

 

 

 

 

 

 

End cells of chains of even length are conjugate pairs, containing true candidates of each number!

Here we have two, a 4-cell (black), extended (red) to a 6-cell remote pair. The combined remote pair removals leave a naked pair 45 in c6, removing two 5’s.

 

The resulting 5-wing in columns 2 and 6 removes two of three 5’s in c5, leaving a decisive clue and naked triple.

Next in the review is Ardv2 278, but you get two weeks to get your solution ready.

That’s because next post will explore a curious situation arising from  Gerald Asp’s comment on Ardv2 38, on which a Sysudoku innovation is brought into question, because I left out a given!

 

 

 

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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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2 Responses to Ardson Very Hard v.2 198 and 238

  1. dovmittelman says:

    Did you mean, “the combined removals leave a naked pair 45 in c6”? I read that as what you probably were trying to say.

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