Tag Archives: X-chains

Badger’s Advanced Sudoku


This post highlights David Badger’s two advance puzzles in the Sudoku 1001 Hard Puzzles sysudokie review, both starting with the almost nice loops to be found along the XY railway. In 301, the black XY ANL removes two 7’s, and … Continue reading

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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 … Continue reading

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An Ardson Very Hard Workout


This post checkpoints Ardv2 78, the second review puzzle in A.D. Ardson’s Sudoku Very Hard collection. The puzzle skates by basic and the bv scan, but is tamed on the X-panel. Along with regular collection reviewing posts, I’m revising the … Continue reading

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A Chicken Chok’in Checkpoint on Unhidden Chains


This post checkpoints Royle 17-16774, a rare example in The Hidden Logic of Sudoku of conjugacy chains dealing with a monster cloud of candidates. The checkpoint also catches SudoRules dismembering a “useless” XY nice loop that somehow sneaked into THLS. … 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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Hodoku X-chains on the X-panel


On this post, X-panel chain analysis is illustrated on a Hodoku example. Hobiger’s coverage of X-chains is shallow on fundamentals and distracted with named X-chains. Several X-chain highlights of the blog are recalled. Hodoku starts the chain types with X-chains. … Continue reading

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Absolutely Nasty 4 Review Snaps I


Here we link back to advanced solving posts as we enjoy sysudokie solving snapshots from the review table puzzles 0f Frank Longo’s Absoutely Nasty Level 4 (AN4) collection.  Did you ever get trapped looking at a neighbor’s vacation slides ?  You … Continue reading

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