# Tag Archives: unique rectangle

## KDST 575 Highlights Box Marking

Box marking gets to shine in the redo of Super-Tough, volume 5, book 7, #5. Here is the grid after the relatively modest bypass. The fill strings show where 4-fills were examined, but only one was found. In this snapshot, … Continue reading

## 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

## 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

## 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

## 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

## 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

## 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

## 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

## Suset Jelly in nrc Space

Here we work through an advanced supersymmetry example from The Hidden Logic of Sudoku, without the symmetries.  The humanly practical tools of Sysudoku are entirely adequate to the task. The theme of this review is that the burdensome emulation SudoRules, … Continue reading

## Longo’s Nastiest Ever Collection

This post begins the review of Frank Longo’s The Nastiest Sudoku Book Ever with a  review table and  solving highlights of two review puzzles, Nastiest 607 and 629. The original post was revised to correct errors found by my backup … Continue reading