Tag Archives: ALS toxic set

World’s 36 and 200 Basic, and More on 25


In this post, checkpoint traces on World’s Hardest 36 and 200, and a direct comparison with  two Strmckr solutions to Worlds 25. Also, a Gordon Fick contribution to the cause. Here is Strmckr’s first solution, right out of line marking. It’s … Continue reading

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The ALS Jump Ball


The last review puzzle from the Weekly Extreme Competition, Wex 435, evades the Sue de Coq to give us: a precaution about grouped forcing chains in XYZ-wings, a genuinely extreme patterns trial, and an obvious form of ALS trial to … Continue reading

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Gordon Fick Tricks More Extreme 200


This post reports an alternative solution, without my pattern analysis, to Antoine Alary’s special More Extreme 200, based on a Sysudoku reader’s innovative use of a little known technique, the double common ALS pair. Two ALS sharing two restricted common … Continue reading

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ALS Toxic Sets


A pair of non intersecting almost locked sets can define a toxic set. This kind of removal may be discovered at any time, but I place closure on ALS generated toxic sets very late in the Systematic Sudoku Order of … Continue reading

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