Tag Archives: Stefan Heine

A BARN Storming UHC 353 Finish


This posts finishes left page ultrahardcore 353, using several notable moves to expand a cluster.  Sudokuwiki starts it with a grouped terminal ANL with line and box winks, a regular swordfish expands the cluster, trapping four candidates. Expansion creates an … Continue reading

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Softening left page ultrahardcore 353


Here is another puzzle the DIY oriented solvers suggest is too hard for human solving, even as the moves they find are too instructive to ignore.  This post gets quickly to ALS methods that demand exhaustive enumeration from the DIY … Continue reading

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UHC 309 Rounds the Bases


The ultrahardcore review solvers illustrate a diverse solution path, before and after AIC and cluster building. Here is the grid after the bypass and box marking. Beeby found a naked single SE4 in r8c7 in its basic. The Sysudoku Basic … Continue reading

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The UHC 265 Wrap Up


This post continues on the solution path for left page ultrahardcore 265. We begin where we left off, with the two solvers synchronized and with the first preliminary coloring cluster on the grid. Next, a 3 – ANL creates a … Continue reading

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UHC 177 Stretches It Out


In this post, Heine’s left page ultrahardcore 177 gets from one cluster wrap to two more in a long series of AIC and boxlines. Also included is the review table for uhc 1 -177. Continuing from the green wrap of … Continue reading

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Wrapping Up UHC 89


This post completes a coloring solution of Stefan Heine’s left page ultrahardcore 89.  Two examples of cluster exit AIC building bring a second finned swordfish, and a cluster exit wrap of the large cluster. After this follow up of last … Continue reading

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A UHC 45 Discontinuous Nice Loop Seminar


Heine’s left page ultrahardcore 45 offers a host of examples illustrating when a Beeby “discontinuous nice loop” is and isn’t a 1-way. Coloring closes the class. UHC 45 has a remarkable number of bv and line slinks, given the monster-like … Continue reading

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Pattern Analysis with Coloring on UHC 1


Coloring can be combined with freeform pattern analysis to determine a small set of pattern trials for Heine’s ultrahardcore 1. Typical choices for this decision are reviewed. A single trial produces the solution. For this we go back to the … Continue reading

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Dov Introduces Lite Coloring of ultrahardcore 311


This post finishes the lite coloring revisit of past trials with Dov Mittelman’s lite introduction. It leads to a solution of Stefan Heine’s UHC 311 without trial. This puzzle occupied 3 posts in the ultrahardcore review, starting with November 3. … 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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