Category Archives: Advanced Solving

Techniques applying after candidates are identified. Why they work. How and when to look for them.

Ultrahardcore 3 Falls to Coloring Trials


This post reports coloring trials that gain the solution after forcing chains when Sudokuwiki gives up.   This includes an example of a grid diagram illustrating the route to contradiction in a breath first trial trace. Then we close with a comment  … Continue reading

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An Orphan Takes Down Nakamoto Extreme 163


In this post, AIC building is replaced by BARN’s, conventional chains, coloring, and a noteworthy pattern analysis result. Nakex 163 basic starts with a 3-fill. The bypass contains six more. Two resolve into clue and naked pair, and one, into … Continue reading

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Nakamoto 143 Avoids Extremes


Nakex 143, the eighth puzzle in the review, avoids AIC building with an outstanding exhibition of advanced techniques, and three subsets in basic line marking, including this naked triple. Two more show up in LM closing, the stage that examines … 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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A Pattern Analysis Attack on Nakex 103


This post reports an alternative Sysudoku solution to Nakamoto Extreme 103, starting with a pattern analysis signaled on an X-panel. The analysis develops and exploits a coloring cluster to accelerate the solution.         The starting cluster is … Continue reading

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A Nakex 83 BARN Storming Finish


This post details the unusual finish of Nakamoto Extreme 83, with three more interdependent BARN’s, well assisted by Medusa coloring. From the first cluster trap and BARN, further expansion and the aligned triple continue to move Nakamoto Extreme 83 towards … 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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Nakamoto Extreme 43 Redefines Sysudoku Extreme


This post recounts another AIC building project of 15 boomerangs, Nakamoto Extreme 43. The Nakamoto Extreme collection justifies the ‘extreme’ label by possibly exhausting the time and patience of a human solver.  Let’s say, if a puzzle justifies a trial … Continue reading

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Cluster Maintenance Pays in Nakamoto Extreme 23


In this post, a cluster wrap interrupts the Sudokuwiki march on Nakamoto Extreme 23, with an abrupt collapse. The following post then follows the original solution through to another example of Andrew Stuart’s “digit forcing chain”, to note that human … Continue reading

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Nakamoto Extreme 3 Exits in Full Color


This post continues the Sysudoku report and supplemented Sudokuwiki solution of Nakex 3. We pick up from last week with matching  8 pairs in E and SE. The starting slink has been available since Sudokwiki entered AIC building, but new … Continue reading

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