Tag Archives: XYZ-wing

Hodoku Grouped AIC II


This post continues with two more Hodoku examples, which illustrate how a human solver finds grouped AIC. As usual, Hobinger attributes them to making just the right premise at just the right place. In the Hodoku Grouped AIC section, the … Continue reading

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Hodoku’s Limited XYZ Wings


In this post reviewing the Hodoku Wings page linked under Techniques, we see how an expert programmer can go wrong in explaining how to recognize where a technique applies and why it works . The omission of irregular wings is … Continue reading

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Wex 429 is Sued


In the review of a sequence of 10 Weekly Extreme Competition puzzles, Wex 429 is toppled by an easily verified Sue de Coq. The post begins with a checkpoint for the reader’s own solution of Wex 428 by single alternate … Continue reading

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More Extreme?


Here we begin a review of the second collection of Antoine Alary’s Extreme series, with general comments, a review table, and a checkpoint on the Sysudoku solving on More Extreme 64, a puzzle that is typical of the “generous” variety … Continue reading

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Gordon Guide Puzzle Review


This post reviews the collection of 700 Frank Longo puzzles following the text in the Gordon Guide to Solving Sudoku. A review table summarizes the Sysudoku rating of 10 preselected puzzles, and one advanced puzzle is analyzed in detail. The … Continue reading

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Bent Naked What?


Here I object to Bob Hanson’s use of the XY-wing and the XYZ-wing, in Sudoku Assistant – Solving Techniques, to introduce his more complicated concept of “bent naked subsets”. This treatment limits the wings to unit based links.  Also I’m … Continue reading

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KD Insane 485 One Clue Better


  The Sudokuwiki solution of Insane 485 is reported, starting with the ALS boomerang, but with an extra clue provided by a rare pattern trial. It so happens that one of the two candidates of the ALS 9-group belongs to … Continue reading

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Shortz’ Ferocious Falls Short


Here I have to report a surprisingly poor showing, as an advanced solving collection, of Will Shortz’ “Beware! Very Challenging” puzzles from his 2008 book, Ferocious Sudoku. Will Shortz collection books are by far the best known among U.S. Sudoku … Continue reading

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ER Winks, Forcing Chains and Irregular XYZ-wings


This post introduces “Empty Rectangle” weak links (ER winks) as a form of “seeing”. It is shown how the ER can be extended by a more general form, the forcing chain. It is also demonstrated that XYZ wings can be … Continue reading

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Regular XYZ-wings


This post explains how the regular XYZ-wing and WXYZ-wing make eliminations with toxic sets. Regular XYZ-wings are illustrated, and the XYZ form of the bv map is introduced. If you are following the Order of Battle, you should be returning … Continue reading

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