Category Archives: Puzzle Reviews

Reviews of preselected puzzles from published collections. Summary review table, and highlight analysis.

Ultrahardcore Review ALS-wings II

Posted on April 13, 2021 by Sudent

The  ultrahardcore ALS-wing survey continues with examples from UHC 47. The survey illustrates how ALS-wings are found as ALS are added to ALS maps. Continuing the survey into a second review puzzle UHC 47, the reward is this well laid … Continue reading →

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Continuing the Box ALS Scans for UHC 311

Posted on March 23, 2021 by Sudent

This post continues with the box to box, row and column scans for ALS_XZ.  The C and S ALS fit into one red/orange cluster with a trap. The clusters meet in cell r7c8, showing that blue or orange or both … Continue reading →

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Building ALS Maps With Suset Tables

Posted on March 9, 2021 by Sudent

This post displays the ALS map for rows of UHC 311, at the moment when the Beeby solver returned the first ALS_XZ. The suset ALS marking and building aid is introduced, and suset tables for rows, columns and boxes are … Continue reading →

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A Lite Update on Castillo’s Only Extreme 347

Posted on January 26, 2021 by Sudent

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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A Lite Coloring Update of Castillo’s Only Extreme 261

Posted on January 19, 2021 by Sudent

This post is the first of several which update earlier review solutions to include a new guy in town, lite coloring. The earlier posts will be left as they are, except for added links to these updating posts. Instead of … Continue reading →

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An Error Hides a Lite Coloring Trap on ultrahardcore 399

Posted on January 12, 2021 by Sudent

This post corrects an error on the post of December 8, that prevents a lite coloring trap in ultrahardcore 399. Then there’s follow up on the trap, with the lite coloring marking in place. Trial is not avoided, but the … Continue reading →

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Pattern Trials Peel the UHC 487 Onion

Posted on December 29, 2020 by Sudent

The ultrahardcore review ends, with Stefan Heine’s 487 giving up a naked single and two skyscrapers, and a jaw dropping complex 1-way, shuts down the solver team. Slicing at it with three onion peeling pattern trials leaves very little for … Continue reading →

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SASdC Unlock UHC 443 for Beeby

Posted on December 22, 2020 by Sudent

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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Beeby Softens Up ultrahardcore 443

Posted on December 15, 2020 by Sudent

This post reports a series of Beeby ALS-XZ featuring alignments in Z and X, almost to the point where a trial is needed. A simple basic trace means a hard start, with a crowded grid. Sudokuwiki’s 579-wing is a Beeby … Continue reading →

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Lite Coloring Informs a UHC 399 Trial

Posted on December 8, 2020 by Sudent

In one post, the 10th ultrahardcore review puzzle is wrapped, but not without an introduction of something new in Systematic Sudoku. Ordinarily advanced steps begin in line marking, and lite coloring is introduced. In line marking Stefan Heine’s ultrahardcore 399, … Continue reading →

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