Tag Archives: unique rectangle

PencilPress 81 and Master Class 110


This post concludes the review of PencilPress’ 500+ Sudoku Extreme Puzzles, and adds another puzzle to the review update of Tom Sheldon’s Master Class Sudoku. T The final score was PencilPress Extreme 0, Sysudoku Bypass 10. If “Extreme” means requiring … Continue reading

Posted in Advanced Solving, Basic Solving Procedures, Expert Reviews, Puzzle Reviews, Sheldon, Sheldon | Tagged , , , , , , , , | Leave a comment

Lucky Panda Books Extremely Hard 48


LPB 48, the first review puzzle of Lucky Panda Books 504 Sudoku Puzzles, features an interesting hidden dublex and many unresolved 3-fills with fill strings trimmed by line slinks. The easy line marking closes with a DIY unique rectangle. A … Continue reading

Posted in Advanced Solving, Puzzle Reviews | Tagged , , , , | Leave a comment

A funster Extreme 116 Labor Day Special


An effective bypass, and a simple uniqueness rectangle, and three choices to close down funster Extreme 116 early. Charles Timmerman’s funster Extreme collection is less than  extreme, but a good introduction to advanced solving methods. The basic work is easy, … Continue reading

Posted in Advanced Solving, Puzzle Reviews | Tagged , , , , , , , | Leave a comment

Another Look at Ardson Very Hard v.2 38


This post brings up an interesting question about the multiple solution puzzle: Does its ambiguity prevent strictly logical solving from reaching a solution? Introducing the first selected review puzzle of the A.D. Ardson Very Hard v.2 collection on April 11, … Continue reading

Posted in Advanced Solving | Tagged , , | 6 Comments

A Run Through Ardson’s Very Hard Volume 2


This post begins a review of A.D. Ardson’s Sudoku Very Hard Puzzles, volume 2. The review will cover 10 pre-selected puzzles from 400, every 40 starting with number 38. Well, almost. The puzzle at the end of the previous post … Continue reading

Posted in Puzzle Reviews | Tagged , , , , , , , | 2 Comments

Remaining THLS XV hXY Avoided


Here we complete the report on the puzzles selected in The Hidden Logic of Sudoku to show that hidden XY chains are an “inescapable tool for the advanced player”, and therefore  require the generation and maintenance of symmetry grids. None … Continue reading

Posted in Advanced Solving, Berthier, Puzzle Reviews | Tagged , , , , , , | 2 Comments

THLS vs. Unique Rectangle


This post updates the UR chart, with credit to Denis Berthier, then debunks another unfortunate THLS pronouncement. The homework puzzle illustrates another penalty a human solver pays for interpreting  The Hidden Logic of Sudoku as solving advice. Now in our … Continue reading

Posted in Advanced Solving, Berthier, Expert Reviews | Tagged , , , , | 4 Comments