Category Archives: Expert Reviews

Reviews of definitions and solving advice published by Sudoku experts.

Sharing Hanabi’s Secrets


This post details a fireworks analysis on “Hanabi”, shye’s fifth example. The first four examples used matching elbows alone, along with bi-value cells. This one uses forcing chains to identify the value winning placement in the neck cell shared by … Continue reading

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Fireworks 4 Stretches the Matched Elbow Rule.


After a challenging basic, we get two matched pairs on two values again, but this time, linked by a single bv. The second challenge is the application of the matched elbow rule of the last post in a more hypothetical … Continue reading

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Fireworks 3 Matches Elbows and Bv


This post develops a property of a 2 value elbow match, and uses it with matching bv. Before we start on that, here are the elbow panels for the last week’s second example, just in case you want to compare … Continue reading

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X-panel Elbows for Fireworks


This post illustrates the use of the Sysudoku X-panel for fireworks analysis, as introduced  in forum corresponent shye’s first two examples. Here is shye’s statement of the fireworks principle: What does this actually mean? Given a row, column and intersecting … Continue reading

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Ultrahardcore Review ALS-wings III


This post’s examples from UHC 179 include ALS-wings with bv cells, and uncover two essential facts about ALS value groups. This post’s examples include ALS-wings with bv cells, and uncover two essential facts about ALS value groups. Instead of following … Continue reading

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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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