Category Archives: Advanced Solving

Techniques applying after candidates are identified. Why they work. How and when to look for them.

A KDST 595 Hidden Weakness


In KrazyDad SuperTough v.5, b.9, n.5, an almost naked triple is concealed, awaiting a single elimination. It’s not something reasonable to search for, but two systematic constructions get you there. An otherwise anemic bypass fills the NorthEast box, but slink … Continue reading

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KDST 585 Favors the Bypass and Coloring


In spite of a big bypass, Krazydad Super-Tough v.5, b.8, #5 requires some work. An extensive XY railroad looks good, but a comparison with Medusa coloring favors the latter. This brings an opportunity to show unusual coloring resolutions, one involving … Continue reading

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KDST 575 Highlights Box Marking


Box marking gets to shine in the redo of Super-Tough, volume 5, book 7, #5. Here is the grid after the relatively modest bypass. The fill strings show where 4-fills were examined, but only one was found. In this snapshot, … Continue reading

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Super-Tough 565 Wrapped Twice


In this post, KrazyDad Super-Tough v.5, b.6, #5 survives a wrap of one coloring cluster, only to fall to a second. The bypass starts with two 3-fills, one resolved. Then in line marking, there’s an outbreak of naked pairs. Here … Continue reading

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KrazyDad Super-Tough 555


This post’s  basic trace on Super-Tough v. 5, b. 5, #5 illustrates the full use of 3-fills in the bypass, and closes with a six node remote pair. On the grid as the bypass is completed, S9 is marked as … Continue reading

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Krazydad Super-Tough 545 Wraps Up Fast


It’s mostly in Basic with Super-Tough v. 5, b.4, # 5. The post of March 26, 2013 reports a long XY chain, followed by two remarkable irregular XYZ-wings, then two finned swordfish. However, this update shows that the generous bv … Continue reading

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KrazyDad Super-Tough 525 Review Update


This post has an updated solution of KDST 525, starting with a 3-fill and a rare remote pair. The bv scan has an irregular XYZ-wing, and the 6-panel features a  long XY nice loop that illustrates the XY Railroad on … Continue reading

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KrazyDad Super-Tougn 515 Starts a Review Update


This post begins the update review of the Super-Tough collection available on krazydad.com with volume 5, book 1, number 5. The Super tough collection was first reviewed in March 2013, but that was one of the first reviews on Sysudoku, … Continue reading

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Complex 1-ways Take Out KDI 475


This post updates KrazyDad Insane v.4, b.7, #5 with a bypass 4-fill and a solution free of trials, unless you consider the complex 1-way a trial. To the line marking, we add Beeby’s UR. If 6r1c7, the 9 slinks carry … Continue reading

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The Complex 1-Way in AIC Building


This post is about an AIC building option offered by Philip Beeby’s PhilsFolly.com solver, and how and where it is best applied in DIY solving.  Here we refer to this solver as Beeby and this technique as complex 1-way.  Complex … Continue reading

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