Category Archives: Expert Reviews

Reviews of definitions and solving advice published by Sudoku experts.

BV Scan Satisfaction in Saturday 2


This post continues the visit of Sudoku Satisfaction readers to Sysudoku with a tour of  advanced method principles applied in a Sysudoku solution of Satisfaction’s Saturday 2 puzzle. The roles of Rick Seemel’s Solution Rectangles I – IV in the … Continue reading

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Touring the Bypass and a Human Engineered Inscription


This post continues the visit of Sudoku Satisfaction readers to Sysudoku with a demonstration of the slink marking bypass, line marking inscription, and basic subset spotting. How was lunch?  . . .  Good. OK, we’re ready to continue. Here is … Continue reading

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The Sudoku Satisfaction Tour


In the next three posts, I introduce Sudoku Satisfaction  by Richard Nicholas Seemel, by inviting sysudokies to attend a tour for Satisfaction readers. The tour will highlight differences between  two systems that agree on basic solving approach, but not on … Continue reading

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A Closing ALS Postscript on THLS


This post demonstrates ALS-XZ as an alternative to hidden XY chains, and concludes the review of The Hidden Logic of Sudoku by Denis Berthier. In THLS, Denis goes outside the Royles 17 collection only a few times for illustrative examples. … Continue reading

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Berthier’s xyzt Chain


This post concludes my reading of Denis Berthier’s The Hidden Logic of Sudoku, with two example puzzles to illustrate his xyzt-chain. While it is good to be aware of Berthier’s “t” versions of classic XY chains, I don’t recommend a comprehensive … Continue reading

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Berthier’s xyt-Chains Rated Extreme


This post suggests a limited role for Denis Berthier’s xyt chain in human solving. I found no THLS examples of longer chains not requiring prior xyzt or hidden chains.The last prospect, Royle 17-33442 proves to be both unjustified and unnecessary. … 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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