Category Archives: Extreme Solving

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

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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Nakex 183 Hides the Keys


The last review puzzle, Nakamoto Extreme 183, follows the collection’s pattern of hiding easier removals behind methods that are very difficult to spot. An effective defense is to maintain bv maps, X-panels, and coloring clusters carefully as more advanced results … Continue reading

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Nakamoto Extreme 123 Is, Briefly


Nakex 123 limps into AIC building briefly,  then succumbs to Sudokuwiki XY chains, simple coloring traps,  a coloring bridge and an outstanding BARN. Here is the grid at the end of a bypass exceptional among Nakamoto Extreme puzzles. The slink … Continue reading

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Sudokuwiki’s Nakamoto Extreme 103


After Sysudoku Basic, this post describes the Sudokuwiki advanced and AIC solution path on Nakex 103. The next post reports an alternative path shortened significantly by a freeform pattern analysis. Nakex 103 starts a little differently, with some bypass success: … Continue reading

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A Nakex 83 BARN Challenge


Nakamoto 83 earns its Extreme badge by an extremely tough Basic, and resistance to anything short of AIC building. It ends with an expanding cluster, accelerated by a series of BARNs. This post brings you to the first one, and … Continue reading

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Sudokuwiki Ends Nakex 63 On Its Own


This post picks up on the Sudokuwiki/Sysudoku resolution of Nakamoto Extreme 63 where it was overtaken by pattern analysis and coloring, and finishes it in two ways, one humanly practical and one not. Sudokuwiki doesn’t maintain coloring clusters between moves, … Continue reading

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Mixed Solutions on Nakamoto Extreme 63


This post reports Sudokuwiki AIC building in Nakex 63, until it is overtaken by pattern analysis and coloring. The solver’s path is continued in the following post. Nakex 63 basic is tough, despite a productive bypass.     The first … Continue reading

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