Category Archives: Extreme Solving

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

Beeby Finishes ultrahardcore 91


The Beeby series continues on trial wounded ultrahardcore 91 until the expanding coloring cluster can  take it home. Is your trial-less solution ready? Next up t is  a 1-way from 1r6c3 that is exended back to 3r2c3 for a second … Continue reading

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Beeby Carries the Post Trial Against ultrahardcore 91


This post and the next continue on uhc 91, after last week’s SASdC trial eliminated red candidates of a red/orange cluster and left two clues. Phil Beeby’s solver chisels on the crystalized structure, conducting an ALS_XZ clinic, until the slink … Continue reading

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Ultrahardcore 47 Pattern Trial


This post bypasses Sudokuwiki’s  forcing chain parade with a value pattern trial, strengthened by the Single Alternate Sue de Coq analysis of the last post.  One pattern is tried and fails, leaving a coloring cluster. When the trial of the … Continue reading

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Ultrahardcore 47 Single Alternate SdC Trials


This post does the basics on the second Stefan Heine ultrahardcore right page under review.  Then it shows eight ways to do the five advanced moves up to forcing chains, two of them duplicated by boomerangs. It closes by  identifying … Continue reading

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Beeby on Heine’s ultrahardcore 3


This post highlights several moves from Phillip Beeby’s solver, which are alternatives to those appearing in the five earlier posts on Stefan Heine’s ultrahardcore 3. One result is a solution without the second blue green trial, left as a project … Continue reading

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Readers Solve Ultrahardcore 3


This post returns to the Stefan Heine’s utrahardcore  3 solution path just before cell and unit forcing chains. It turns out that an immediate coloring trial reaches a solution without them. Then we report how two Sysudoku readers solve it … Continue reading

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Ultrahardcore 3 Schlagt Forcing Chains


In this post, we continue with Sudokuwiki into forcing chain methods, and their relevance to the ultrahardcore theme. Sudokuwiki stalls, as Stefan predicts.  Then we fashion a trial for a logical, but practical outcome. On the grid after the red/orange … Continue reading

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Cell and Unit Forcing Begins in Ultrahardcore 3


This post reveals yet another way to start a boomerang, and reconsiders the practicality of Andrew Stuart’s Cell  and Unit Forcing Chains, this time facing an ultrahardcore right page. We get to a choice between Sudokuwiki and a coloring trial … Continue reading

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Utrahardcore 3 Lifts Off


The review of Sudoku ultrahardcore 1 right pages, a separate collection from (and tougher than) its left pages, begins with number 3, shown here post before last.  In this post, we follow Sudoku Basic and the Andrew Stuart’s Sudokuwiki solver … Continue reading

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Wrapping Up Nakamoto Extreme With 183


This post completes the review of the Nakamoto Extreme collection. The review table follows the finish of Nakex 183. A Sudokuwiki assisted solution of Nakex 183 continues with the second APE triggered by the first’s removal of 8r2c9. In this one, … Continue reading

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