Ruud at 09:17, 30 October 2021

2021-10-30T09:17:49Z

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	A '''Unique Rectangle''' is a [[deadly pattern]] formed by 4 [[cell]]s that share 2 [[row]]s, 2 [[column]]s and 2 [[box]]es. In [[Sudoku ~~Variations~~]] with additional [[constraint]]s, each of these constraints must either contain 2 cells or none at all. All 4 cells only have candidates for the same 2 [[digit]]s.		A '''Unique Rectangle''' is a [[deadly pattern]] formed by 4 [[cell]]s that share 2 [[row]]s, 2 [[column]]s and 2 [[box]]es. In [[Sudoku Variant]]s with additional [[constraint]]s, each of these constraints must either contain 2 cells or none at all. All 4 cells only have candidates for the same 2 [[digit]]s.

	The name is not well chosen. The pattern causes the puzzle to have at least 2 solutions, so a better name would be '''non-unique rectangle'''.		The name is not well chosen. The pattern causes the puzzle to have at least 2 solutions, so a better name would be '''non-unique rectangle'''.

127.0.0.1: Created page with "A '''Unique Rectangle''' is a deadly pattern formed by 4 cells that share 2 rows, 2 columns and 2 boxes. In Sudoku Variations with additional constra..."

2021-10-25T08:04:17Z

Created page with "A '''Unique Rectangle''' is a deadly pattern formed by 4 cells that share 2 rows, 2 columns and 2 boxes. In Sudoku Variations with additional constra..."

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A '''Unique Rectangle''' is a [[deadly pattern]] formed by 4 [[cell]]s that share 2 [[row]]s, 2 [[column]]s and 2 [[box]]es. In [[Sudoku Variations]] with additional [[constraint]]s, each of these constraints must either contain 2 cells or none at all. All 4 cells only have candidates for the same 2 [[digit]]s.

The name is not well chosen. The pattern causes the puzzle to have at least 2 solutions, so a better name would be '''non-unique rectangle'''.

Here is an example:
{{grid|1=12|4=12|10=12|13=12}}
Rows 1 and 2, columns 1 and 4 and boxes 1 and 2 each contain 2 cells from this pattern. All cells have candidates 1 and 2. There are 2 ways to complete this pattern.

A more concrete example:

[[Image:UniqueRectangleDeadlyPattern.png]]

This puzzle has two solutions.

== A mistake to be avoided ==
The following pattern is sometimes mistaken for a unique rectangle. However, this pattern occupies 4 boxes.

<font color="red">This is not a unique rectangle!</font>
{{grid|1=12|4=12|28=12|31=12}}

== See also ==
* [[Uniqueness Test]]
* [[Bivalue Universal Grave|BUG]]
* [[BUG Lite]]
* [[Deadly pattern]]

[[Category:Uniqueness]]

Unique Rectangle - Revision history

Ruud at 09:17, 30 October 2021

127.0.0.1: Created page with "A '''Unique Rectangle''' is a deadly pattern formed by 4 cells that share 2 rows, 2 columns and 2 boxes. In Sudoku Variations with additional constra..."