Tag Archives: XY-chain

Sudokuwiki Solves Only Extreme 347 by AIC


In the original Only Extreme review, OnEx 347 was an example of a coloring trial on a limited cluster generated by pattern analysis. In this update, Andrew Stuart’s solver demonstrates a solving path to a final coloring without trials, via … Continue reading

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Coloring Wrings Out World’s Hardest 102


World’s 102 starts without ‘1’ givens and with two 3-fill lines. It winds up in a coloring trap expansion into a wrap. Basic makes progress in all three phases.               Making a hasty bv … Continue reading

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Only Extreme 132 Is Cut From the Extreme Team


Another example of expansion of a limited coloring network via the not-both test on an AIC slink. It’s an extreme tactic that need only be tried as a last resort. While the expansion does work in OnEx 132, it is … 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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Ardson Very Hard v.2 318


The review continues the pattern with Ardv2 318. Ignore the pencil marks and pick out the givens if you have to, but try the bypass.  It gets close to the edge, leaving three 3-fill lines for box marking.     … Continue reading

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Ardson Very Hard v.2 278, Plus 38 Comments


A conversation about multiple solution puzzles and coloring may be developing, as the A.D. Ardson review plods on.  On Ardv2 278, hidden pairs (naked triples) compensate for a weak bypass.  The puzzle falls to yet another XY chain. Two regulars … Continue reading

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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 … Continue reading

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