Tag Archives: pencil marking

Recovering From a Small Disaster


This post corrects an incorrect homework assignment, and announces some changes in Sysudoku due to a switch to a new computer and updated operating system. Last week was not a good one. On Tuesday I posted an incorrect puzzle for … Continue reading

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Basic Sudoku With Arnold


This post compares Arnold Snyder’s basic solving methods, the techniques leading to a full set of candidates, with Sysudoku basic.  Snyder’s basic methods are described in Sudoku Formula 1 and Formula 2. A second post will evaluate the Snyder advanced … Continue reading

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The 2013 Akron Sudoku Tournament


Here’s my report on the second successful Sudoku tournament put on by the Akron-Summit County Library.  Yours truly didn’t complete a single puzzle in the contest, but I renewed acquaintance with some phenomenal solvers.   I’m including a trace and checkpoint … Continue reading

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Box/Line Reduction


In a box/line reduction, or “box/line” for short, a line’s candidates for a number are restricted to one box. That makes these candidates a toxic set, since one of them must be supplied to the line.  We can remove other … Continue reading

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Line Marking Follow Up Actions


This post describes the follow up to the candidate fill of each line in Sysudoku line marking.  This includes the marking of line slinks, checking for X-wings, identification of  naked and hidden singles, and marking of bi-value cells. It also … Continue reading

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Sysudoku Line Marking


This post describes the Sysudoku basic technique of line marking, which pencil marks all remaining candidates, line slinks and bi-value cells.  In a walk through line marking of the Sue de Coq classic, the efficiencies of line marking are explained. … Continue reading

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Sysdudoku Box Marking


This post describes in detail the procedure of box marking, the first of two basic solving stages of Systematic Sudoku.  Box marking identifies and marks slinks and naked subsets within boxes, as well as new clues.  A walkthrough illustrates  the … Continue reading

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