Monthly Archives: July 2017

Bean’s Extremely Hard I

A review of Rebecca Bean’s 600 Extremely Hard Sudoku Puzzles with Answers begins with the review table and two puzzles, 7-6 and 12-6. The collection is mostly basic, with the half of them solved by the slink marking bypass. Puzzle … Continue reading

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Dave Green’s Three Column Bypass 3-Fill

This post traces the bypass solution of Dave Green’s Friday **** of July 7, 2017, an amazing follow up to my recent addition of 3-fill’s to the slink marking bypass. This puzzle, starting with  three column 3-fills among the givens, … Continue reading

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Slink vs. Coloring Networks and Illogical Sudoku

This post reports a surprising fact about multiple solution puzzles, that solutions found by backtracking tree search can be logically inconsistent. Specifically, such solutions violate the coloring network implied by the givens. I happened on this fact by means of … Continue reading

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Closing Very Hard v.2 with the Real 38

To be fair, here is my do over of the real Ardv2 38, the one with a given 7 in r7c6.  My omission of it hatched a productive distraction, having no bearing on the collection it came from. The basic … Continue reading

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