Category Archives: Sudoku Toolware

What we’ve got and how to use it.

The ALS Petaled Death Blossom


Today we illustrate the full blown Death Blossom with ALS petals. Earlier I noted Death Blossom Lite as a removal technique in the bv scan.  Completion of a DB Lite with a closing ALS is also relatively easy to find.  … Continue reading

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Coloring Sue de Coq and APE


Coloring is a general purpose weapon.  It limits the puzzle’s  ability to satisfy the restrictions imposed by  Sue de Coq and APE .  This explains why sysudokies  record the “almost” patterns found in the bv scan, and return to them … Continue reading

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The Slink Magic of Coloring


Coloring is magic. It invokes the power of the strong link in ways that normally escape our attention. In coloring, we construct networks of slinks, called clusters. Each candidate of a cluster has one of two colors. Each of this … Continue reading

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Unraveling the Mutant Fish


This revised post explains what mutant fish are, and the rule used to eliminate candidates. It offers a hard-to- find proof that this rule works, and some spotting tips. Regular fish, finned fish, and sashimi fish are candidate elimination methods … Continue reading

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Krakening a Finned Fish


Virginia, your mother tells me how your playground friends told you frightening tales about Harry Potter’s kraken monster  when you mentioned the kraken fish you saw at the aquarium.  You needn’t worry, dear.  There’s no such thing as a kraken … Continue reading

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Casting for Regular Fish


How do you spot regular fish? An effective radar is the set of markings that you saw in the blank lines of the “Complementary  Swordfish” panel of the last post, repeated here: Looking from left to right, I marked the … Continue reading

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What Regular Fish to Fish For


Come let us reason together about regular fishing, i.e. finding X-wings, swordfish, or jellyfish on an X-panel .  We look at sets of lines in one direction, then the other.  Rows and columns.  We seek a set of n lines … Continue reading

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The X-Panel and X-Chains


We will now be leaving methods relying on the bv map as the primary visual aid. With puzzles that survive these methods,   we need to remember that the bv map file remains an important resource.  With every clue or candidate … Continue reading

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The Remote Pair – A Special XY-Chain


The remote pair comes your way with a blinking road sign. It is an XY-chain in which every bv along the chain contains the same two candidates, X and Y. The X and Y in the end cells are toxic. … 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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