Category Archives: Expert Reviews

Reviews of definitions and solving advice published by Sudoku experts.

Master Class 120 Completes the Update


This post concludes the review update of Tom Sheldon’s Master Class Sudoku and offers an amended review table. The bypass on Master Class 120 is strong enough to keep line marking fill strings short. There are two naked singles, one … Continue reading

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PencilPress 81 and Master Class 110


This post concludes the review of PencilPress’ 500+ Sudoku Extreme Puzzles, and adds another puzzle to the review update of Tom Sheldon’s Master Class Sudoku. T The final score was PencilPress Extreme 0, Sysudoku Bypass 10. If “Extreme” means requiring … Continue reading

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Logic Justifies Aligned Triple AIC Hinges


This post takes on a challenge puzzle 17 which follows the Figure 30.1 of the previous post, in Andrew Stuart’s The Logic of Sudoku.   A boomerang ANL shows why aligned triple candidates are eligible to be AIC hinge partners. Logic … Continue reading

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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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Andrew’s Solver Tames Worlds 200


This post walks through the “very  hard” part of the solution path taken by  Andrew Stuart’s Solver through puzzle 200 of The World’s Hardest Sudoku Book by authors unknown. This is a remarkable turn of events for a blog devoted … Continue reading

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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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Strmckr’s Double Common ALS_XZ


This post translates an instructive example from “strmckr”, an expert forum contributor, and adds some observations about double common ALS_XZ.  Then Sudent comments on some Sudoku history that Strmckr included with his example. In his comments on the April 10 … Continue reading

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