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.

Sysudoku Home Page

Posted on July 19, 2022 by Sudent

Systematic Sudoku (Sysudoku) is a human engineered way to solve Sudoku puzzles, and provides graphic and completely documented examples and collection reviews at all levels. Diagrams and tables that aid solving are demonstrated.  Over 500 weekly posts give complete examples … Continue reading →

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Closing With the Hidden Dublex

Posted on July 12, 2022 by Sudent

This closing post adds two examples of a fierce looking line marking being de-fanged by hidden dublex on the over abundant X values A double line exclusion, or dublex, is one of the primary moves of Basic sudoku, in which … Continue reading →

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Bring Your Boxline for Extreme Hard 1505

Posted on July 5, 2022 by Sudent

I was closing down the weekly posts with a set of scroll down basic level puzzles, when I got another collection book , 3000 more “very hard to extreme “, for Adult puzzles. I did a few from the extreme … Continue reading →

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An AndrewsMcMeel  6-Star Sample 4-fills Out

Posted on June 28, 2022 by Sudent

Scroll back for the givens grid. After the fourth 4-fill, we never get back to the three unresolved 3-fills in the bypass trace. Here is the grid, just before SE6 (halfway down) wipes out the naked pairs. The Sysudoku basic … Continue reading →

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A Filling USA Today Weekend 5-Star

Posted on June 21, 2022 by Sudent

Starting with a 2-fill, two 3-fills, and a 4-fill near collapse, there’s value by value action left in the bypass for only one value. Scroll back for the givens and trace out the bypass. An x-fill lists the values to … Continue reading →

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A Kampelmann Hard With Bypass Coloring

Posted on June 14, 2022 by Sudent

Ever have a Sudoku fail to tie down a solution? Hard 109 of last post seems to fail to do so without a trial. Coloring, which has found many multiple solutions, defines the unique solution for this one. Starting with … Continue reading →

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A Washington Post ****** Basic

Posted on June 7, 2022 by Sudent

Scroll back one for the reason for the change in plans, but this is the first of several weekend puzzles from the Washington Post, added at the last minute for additional illustrations of Sysudoku Basic solving.   Basic starts with … Continue reading →

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A Harder Kampbelmann, Barely Basic

Posted on May 31, 2022 by Sudent

Hard 143 starts with a stingy bypass, and requires box marking and some line marking. In the bypass, a r9 3-fill resolves  into SW8and the naked pair 36. W8 then follows, either from the 8’s dublex, or  from the West … Continue reading →

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Naked Pairs Carry the Ball in Hard 134

Posted on May 24, 2022 by Sudent

A second Kampbelmann Hard is tough on paper, but  gives way routinely to a systematic bypass. Here is the grid well into the bypass, with a large number of cells held in reserve by box filling naked pairs. In the … Continue reading →

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A Hard, But Bypassed Kampbelmann 50

Posted on May 17, 2022 by Sudent

My Basic bypass starts with a resolved 4-fill. Did yours?  The final collapse begins with the value 8 scan resolving the naked pair left from the resolution of 3-fill c2[258]. In the bypass trace, you can discover when the previous … Continue reading →

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