Unique Rectangles Gallery

Everything about Sudoku that doesn't fit in one of the other sections

Unique Rectangles Gallery

Postby David P Bird » Sat May 13, 2017 1:02 pm

The coverage of Unique Rectangle and Avoidable Rectangle inferences and eliminations is scattered throughout this forum, so recently I worked on a personal gallery of the possible patterns. I have now added annotations etc. to make them suitable for others to understand, and attach the result as an Open Office file.

In 2006 Mike Baker did a tremendous job in compiling a collection <here> of the different UR configurations that he and others could discover or devise, and listing the eliminations that each one produced. At that time the collaborators allocated UR type numbers in the order that they were discovered so they were rather illogical, but they are still in use. Mike did not use these type numbers, but used his own comprehensive system. In 2006 different notation systems were in flux, so diplomatically, he only listed the eliminations that were available. He also excluded deductions that utilise external disrupting nodes, as the members of the team would have been well aware of the implications. These points, together with the terminology he used, make his listing difficult reading.

In the gallery, I have adapted his indexing system and have added AICs to justify the eliminations provided by the patterns. Understanding AICs is therefore a prerequisite to be able to follow the logic involved. The indexing system used is meant to support the listing order, nothing more, as it should be easier for readers if the chain notations are given in preference to quoting pattern numbers.

As usual, I would be grateful for any comments or corrections and would welcome a collection of sample puzzles if anyone has one to complement the gallery. However, please be warned that nowadays I am only able to work piecemeal on Sudoku, so please accept it may take me some time to respond.

UR Gallery.odt
UR Gallery
(25.11 KiB) Downloaded 15 times


David P Bird

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David P Bird
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