Category Archives: Advanced Solving

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

Fleshing Out Stuart’s ALS Node Figure 30.1


Andrew Stuart’s The Logic of Sudoku, in a chapter on Almost Locked Sets, presents an example of an ALS node in a confirming Almost Nice Loop, as Figure 30.1. This post fills in the solution, before and after the series … Continue reading

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A funster Extreme 116 Labor Day Special


An effective bypass, and a simple uniqueness rectangle, and three choices to close down funster Extreme 116 early. Charles Timmerman’s funster Extreme collection is less than  extreme, but a good introduction to advanced solving methods. The basic work is easy, … Continue reading

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Funster Extreme 102 Goes BOGO


Barely escaping the bypass, funster Extreme 102 offers a thematic example as inference chain seeing nets an extra victim for the collapse. Close to a bypass victim, Extreme 102 finishes basic quietly. On the line marked grid grid is a … Continue reading

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Early Coloring on funster Extreme 32


This post tries for a quick victory on Funx 32 with coloring, without the usual bv scan and X-panel preliminaries. That appears to flop, until three remote pair chains are connected into a long XY chain to wrap two clusters. … Continue reading

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Funster Extreme 18 Stays in the Lines


After a brutal encounter with the bypass, what’s left of funx 18 is riddled with bv. A cluster covering  half the grid expands with a trap to wrap a color and finish the puzzle. The post concludes with an update on … Continue reading

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Funster Extreme 4 has a Near BUG


The review of the Extreme section of Charles Timmerman’s Funster Hard to Extreme Sudoku is underway, with Funster Extreme 4. Funx 4 has a near BUG, but it gets to the doctor early and takes Dr. Stuart’s medicine dutifully. An … Continue reading

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A Guide Update and a Funster Kick Off


The threat of a “The World’s Hardest Sudoku” now relieved, this post starts a review of the “extreme” section of Charles Timmermans Funster Hard to Extreme Sudoku. But mostly, it’s a progress report on the Guide, a set of pages … Continue reading

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