Tag Archives: XY railroad

Hodoku XY-Chains


As we explore Hodoku Chains and Loops (tech-chains.php) examples, here I contrast the premise starting, chain following school of Stephens/Hodoku, with the Sysudoku find-em-all technique of XY-rails. Also, a mathematically sensible order is suggested for remote pairs, as a Hodoku … Continue reading

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Sadistic Sudoku Review


No, it isn’t a sadistic review. I’m reviewing Arnold Snyder’s Sadistic Sudoku collection of puzzles. Arnold’s solving advice, as presented in his “Sudoku Formula” books 2 and 3, will be analyzed in the following post. Two typical review puzzles are … Continue reading

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Riding the XY Rails


This post illustrates the complete enumeration of all XY-chains and toxic end pairs by drawing curves through the bv along XY-chain routes. XY-chains are then systematically divided into sub-chains with toxic ends. It’s a Sysudoku innovation. The puzzle is from … Continue reading

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