Tag Archives: color wrap

The World’s Most Over-Titled Sudoku Book


This post starts the review of World’s Hardest Sudoku Book, tracing Very Hard 25, the only one rated a 1.00. The review will cover the highest rated 10, taking the rating down to 0.90. The lowest of the 200 is … Continue reading

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A.D. Ardson’s Sudoku Diabolical


This post begins a brief review of A.D. Ardson’s Sudoku Diabolical, with a review table and analysis of the first of a pre-selected series 30, 70, . . . , 390. Ardson’s Sudoku Very Hard Puzzles, volume 2, very similar … Continue reading

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A Very Hard Finale with Ardv2 398


A hard basic leaves it to an unusual ALS to shake things loose, enabling an XY and a UR to wrap it up.  Maybe the hardest of the pre-selected Very Hard.   Line marking looks easy, until you look at … Continue reading

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More Satisfaction in Saturday 2


This post completes the last hour of the Satisfaction Sudoku tour of Sysudoku, with alternative solution paths beyond the bv scan in Saturday 2. It features a finned X-wing, a coloring wrap, and an alternative freeform pattern analysis with a … Continue reading

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An xyt Color Wrap


In the spirit of Valentine’s Day, I come across a coloring resource in Berthier’s xyt chain. The elaboration of Royle 17-20565 in Chapter XVII of The Hidden Logic of Sudoku is a challenge in itself. By the theory of looking … Continue reading

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Berthier’s xyt-chains in THLS


Next we review the introduction of xyt-chains in The Hidden Logic of Sudoku. These are modified XY-chains which allow extra candidates in the chain cells, and unlike regular XY-chains, make eliminations regardless of whether the chain starting candidate is true … Continue reading

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THLS Limps In On Chains


This post identifies the conjugacy chain, the last fundamental chain type to be introduced in The Hidden Logic of Sudoku, as a weakened X-chain.  Since the last few chapters introduce extensions for XY chains, it becomes clear that THLS is … Continue reading

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