Category Archives: Extreme Solving

Extraordinary techniques deferred past advanced ones, because of effort vs. likelihood of success.

Building the ALS-wings of UHC 3


This post begins a review of examples of ALS-wings from the ultrahardcore review. The review will illustrate a DIY strategy for constructing them, that is compatible with the concurrent ALS mapping and ALS_XZ building processes of the previous posts. Ultrahardcore … Continue reading

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An ALS_XZ Wrap Up of UHC 311


This post shows what it means to maintain three three ALS maps. ALS map updates are followed through a series of  ALS_XZ until a decisive coloring wrap on Stefan Heine’s ultrahardcore 311. We are exploring ALS mapping as ALS_XZ scans … Continue reading

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Scanning the Column ALS and Some ALS Coloring


This post displays the column and box ALS maps, and scans for AIC the columns. The box scans are started, but get interrupted by an ALS coloring expansion. We start with the ALS column map on ultrahardcore 311 . It … Continue reading

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Building ALS Maps With Suset Tables


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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Coloring ALS Value Groups in UHC 311


This post introduces the expansion of coloring clusters by coloring groups by grouped strong links, such as the those between value groups in ALS. This advance is especially significant as we address whether or not to exhaustively construct ALS and … Continue reading

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Lite Coloring Avoids Trials in KrazyDad 425


This post backs up your lite coloring effort, I hope, on KrazyDad 425. The initial lite trees deliver a cluster merge, and as these grow, lite coloring gives two confirmations and a coloring wrap to finish without trial. The first … Continue reading

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Pattern Trials Peel the UHC 487 Onion


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


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


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


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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