Author Archives: Sudent

About Sudent

I'm John Welch, a retired engineering professor, father of 3 wonderful daughters and granddad to 7 fabulous grandchildren. Sudoku analysis and illustration is a great hobby and a healthy mental challenge.

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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Ultrahardcore Review ALS-wings II


The  ultrahardcore ALS-wing survey continues with examples from UHC 47. The survey illustrates how ALS-wings are found as ALS are added to ALS maps. Continuing the survey into a second review puzzle UHC 47, the reward is this well laid … Continue reading

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Building the ALS-wings of UHC 3


This post begins a review of examples of ALS-wings from the ultrahardcore review. The review will illustrate a DIY strategy for constructing them, that is compatible with the concurrent ALS mapping and ALS_XZ building processes of the previous posts. Ultrahardcore … Continue reading

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An ALS_XZ Wrap Up of UHC 311


This post shows what it means to maintain three three ALS maps. ALS map updates are followed through a series of  ALS_XZ until a decisive coloring wrap on Stefan Heine’s ultrahardcore 311. We are exploring ALS mapping as ALS_XZ scans … Continue reading

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Continuing the Box ALS Scans for UHC 311


This post continues with the box to box, row and column scans for ALS_XZ.  The C and S ALS fit into one red/orange cluster with a trap. The clusters meet in cell r7c8, showing that blue or orange or both … Continue reading

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Scanning the Column ALS and Some ALS Coloring


This post displays the column and box ALS maps, and scans for AIC the columns. The box scans are started, but get interrupted by an ALS coloring expansion. We start with the ALS column map on ultrahardcore 311 . It … Continue reading

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Building ALS Maps With Suset Tables


This post displays the ALS map for rows of UHC 311, at the moment when the Beeby solver returned the first ALS_XZ. The suset ALS marking and building aid is introduced, and suset tables for rows, columns and boxes are … Continue reading

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AIC Building Trial Follow Up for UHC 311


This post returns to AIC building after an encounter with a spontaneous ALS led to expanded coloring and a color trial. That will be normal under a plan of incremental ALS mapping. The confirmation of red had the follow up … Continue reading

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Coloring ALS Value Groups in UHC 311


This post introduces the expansion of coloring clusters by coloring groups by grouped strong links, such as the those between value groups in ALS. This advance is especially significant as we address whether or not to exhaustively construct ALS and … Continue reading

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Recycle AIC Building on UHC 311


This post shows how the AIC building done by the review solvers on ultrahardcore 311 can be systematically duplicated by a human solver. The technique is a graphic one, very amenable to ©PowerPoint graphics, and slink marking of Sysudoku Basic. … Continue reading

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