Tag Archives: unit forcing chains

Ultrahardcore 3 Schlagt Forcing Chains


In this post, we continue with Sudokuwiki into forcing chain methods, and their relevance to the ultrahardcore theme. Sudokuwiki stalls, as Stefan predicts.  Then we fashion a trial for a logical, but practical outcome. On the grid after the red/orange … Continue reading

Posted in Extreme Solving, Heine, Puzzle Reviews | Tagged , , , | 2 Comments

Cell and Unit Forcing Begins in Ultrahardcore 3


This post reveals yet another way to start a boomerang, and reconsiders the practicality of Andrew Stuart’s Cell  and Unit Forcing Chains, this time facing an ultrahardcore right page. We get to a choice between Sudokuwiki and a coloring trial … Continue reading

Posted in Extreme Solving, Heine, Puzzle Reviews | Tagged , , , , , , , | Leave a comment

Nice Loop Coloring of Insane 465


This post introduces nice loop coloring, with a very special nice loop. Pattern slicing has a cameo role. The solution comes in a color trial suggested by  nice loop extensions. Stingiest on the bypass, 465 gives no more clues in … Continue reading

Posted in Advanced Solving, Extreme Solving, KrazyDad, Puzzle Reviews | Tagged , , , , , | 4 Comments

Unit Forcing Chains


Here I explain why sysudokies pass on Andrew Stuart’s Dual Unit Forcing Chains.  We also examine a triple unit forcing chain from Unsolvable 40. As of this post, this statement continues  to appear  in Andrew’s sudowiki.org introduction to Unit Forcing … Continue reading

Posted in Advanced Solving, Expert Reviews, Stuart | Tagged , , , , , | Leave a comment