Tag Archives: hidden unique rectangle

UHC 177 Introduces a Beeby Option


This post gets left page ultrahardcore 177 to coloring with an interesting Sysudoku Basic and a kraken X-wing accessed with a recently added AIC option. Stefan Heine’s ultrahardcore 177 makes many left page concessions, but makes a fight of it. … Continue reading

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KrazyDad Super-Tough 525 Review Update


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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A Lite Update on Castillo’s Only Extreme 347


This post updates a solution by coloring trial in the review post of 12/19/17. A bypass of 6 4-fills resolves 3 of them immediately,  but goes no further than the original 3-fill only bypass.  Then we follow Beeby through a … Continue reading

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SASdC Unlock UHC 443 for Beeby


After the hidden unique rectangle hinted last week, a pair of Single Alternate Sue de Coq trials gets the review solver Beeby moving again. ALS-wings and a finned X-wing get us to a colorful finish. The hidden unique rectangle left … Continue reading

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An SASdC Trial Defeats ultrahardcore 355


In this post a SASdC trial plays like a regular hard puzzle from other collections. The trial amounts to adding two clues, and seeing  what happens.  But it isn’t guessing, and instead of making a small gain, the trial solves … Continue reading

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Systematic FTSPAH 44 and 84


This post demonstrates two more FTSPAH unlikely to frustrate anyone following the Sysudoku order of battle. FTSPAH 44 begins with an unusually large number of givens, which generates a correspondingly large number of 3-fills. In fact, the givens offer both … Continue reading

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Lucky Panda 240 Rides Nice Loop Coloring


The candidates of a nice loop form a coloring cluster. This review puzzle from the Lucky Panda Sudoku review illustrates a decisive nice loop coloring. Two hidden UR 2 show up as well. After a productive bypass and box marking, … Continue reading

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Only Extreme 304 is AIC Level


This post and the next update Castillo’s Only Extreme Sudoku review with a solution of OnEx 304 without trials. Most of the solution path is in AIC building, the most challenging level of Sysudoku Advanced. The only move prior to … Continue reading

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Beyond the Rectangle


The alternative deadly uniqueness formations of the Sudocue Guide are detailed in this post.  Also, there is a UR checkpoint on Sheldon’s Master Class # 3 that goes beyond the UR cases surveyed in recent posts. I can’t leave the … Continue reading

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Stuart’s Hidden UR


In Logic of Sudoku, Andrew Stuart describes a unique rectangle with only one bv corner.  The tell-tale naked pair is not there.  Stuart calls this formation a hidden UR, with good reason.  You have to find the bv candidates in … Continue reading

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