Tag Archives: irregular XYZ-wing

KDST 575 Highlights Box Marking

Posted on July 13, 2021 by Sudent

Box marking gets to shine in the redo of Super-Tough, volume 5, book 7, #5. Here is the grid after the relatively modest bypass. The fill strings show where 4-fills were examined, but only one was found. In this snapshot, … Continue reading →

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KrazyDad Super-Tough 525 Review Update

Posted on June 8, 2021 by Sudent

This post has an updated solution of KDST 525, starting with a 3-fill and a rare remote pair. The bv scan has an irregular XYZ-wing, and the 6-panel features a  long XY nice loop that illustrates the XY Railroad on … Continue reading →

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Ultrahardcore 3 Falls to Coloring Trials

Posted on June 30, 2020 by Sudent

This post reports coloring trials that gain the solution after forcing chains when Sudokuwiki gives up.   This includes an example of a grid diagram illustrating the route to contradiction in a breath first trial trace. Then we close with a comment  … Continue reading →

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The Especially Nice Loop of KD Insane 465

Posted on January 15, 2019 by Sudent

This post reports several features of an update of the post that introduced nice loop coloring. The illustrating nice loop was in itself remarkable. As shown already from books 1 through 5, KrazyDad’s hardest, the Insane collection, is hard enough … Continue reading →

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Funster Extreme 46 Not So Much

Posted on August 7, 2018 by Sudent

The review of Charles Timmerman’s funster Hard to Extreme Sudoku continues with Extreme 46. It’s  entertainingly advanced. Extreme 46 has its moments.  The basic trace is spread across the page with 3-fill after 3-fill. Two unusual events occur in box … Continue reading →

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Coloring Dominates Very Hard III-15

Posted on January 23, 2018 by Sudent

The review of Moito’s Road to Mastery Sudoku continues with another example of early coloring and its cooperative interactions with the X-panel. The advanced path is similar to that of Very Hard I-35 two posts back, but this time coloring … Continue reading →

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How Not to Find a Multiple on Moito’s Road

Posted on January 16, 2018 by Sudent

After a jaw dropping irregular XYZ-wing, a marking mistake reveals an unavoidable UR and two solutions of Very Hard IV-6, then the correction leads to an even more remarkable, but no less unavoidable uniqueness violation. Coloring reveals the logical path … Continue reading →

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Only Extreme 218 Straight Up

Posted on November 14, 2017 by Sudent

Barely escaping the bypass, Manuel Castillo’s Only Extreme 218 gets tough, and brings out some seldom used methods. An alternative trial path by Single Alternative Sue de Coq, normally held in reserve,  follows in a second post. The bypass filled … Continue reading →

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The Akron 2017 Championship Sudoku

Posted on November 7, 2017 by Sudent

This is another Sysudoku analysis of the championship puzzle of the Sudoku tournament put on by the Akron-Summit Public Library. It’s an annual tournament of four rounds, the last being a three person solve – off on poster board grids, … Continue reading →

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Cluster Extension by Not-Both Trials

Posted on August 29, 2017 by Sudent

In this post and the next, the first puzzle of the Manuel Castillo Only Extreme Sudoku review, Only Extreme 3,  is taken ahead of the review of his Only Hard Sudoku. The reason is in the title. Rounding out the … Continue reading →

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