Author Archives: Sudent

About Sudent

My real name is John Welch. I'm a happily married, retired professor (computer engineering), timeshare traveling, marathon running father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. The blog is about Sudoku solving. It covers how to start, basic solving to find candidates efficiently, and advanced solving methods in an efficient order of battle. It is about human solving methods, not computer solving.

Only Extreme 218 by SASdC Trial


This post demonstrates the Single Alternate Sue de Coq with Castillo’s Only Extreme 218. The opportunity for this kind of trial is spotted early in the bv scan, but is best deferred until it is needed as a last resort. … Continue reading

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Only Extreme 218 Straight Up


Barely escaping the bypass, Manuel Castillo’s Only Extreme 218 gets tough, and brings out some seldom used methods. An alternative trial path by Single Alternative Sue de Coq, normally held in reserve,  follows in a second post. The bypass filled … Continue reading

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The Akron 2017 Championship Sudoku


This is another Sysudoku analysis of the championship puzzle of the Sudoku tournament put on by the Akron-Summit Public Library. It’s an annual tournament of four rounds, the last being a three person solve – off on poster board grids, … Continue reading

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Almost Extreme 175 Tags Five Advanced Bases


This post reaches the halfway point in the review of Manuel Castillo’s Only Extreme collection, with Only Extreme 175. A double UR, a regular Sue de Coq and irregular XYZ-wing prepare the bv field for coloring, and an XY chain … Continue reading

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Only Extreme 132 Joins the Extreme Team


Another payoff for expansion of a limited coloring network via AIC slink. It’s an extreme tactic that, after six years of blogging, I finally blundered my way into.  This collection illustrates the not-both trial thoroughly. Please comment if you know … Continue reading

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Only Extreme 89 Guilty on Two Counts


The Only Advanced 46 is followed by a truly Extreme 89. Two different unique Sysudoku trials lead to the same result. The Single Alternate Sue de Coq is deferred, but after advanced techniques fail, it is used.  An equally extreme … Continue reading

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Only Not Extreme 46


The review of Castillo’s Only Extreme collection continues with Only Extreme 46.  A very extensive bypass is survived, to leave very little to add in box marking, and an interesting line marking.  The rest is murder by the usual suspects … Continue reading

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