Rooted: Created page with "'''Common Peer Elimination''' is a basic solving technique that primarily applies to Sudoku Variations with irregular groups of cells, such as Jigsaw and [[Killer]..."

2022-01-20T02:50:55Z

Created page with "'''Common Peer Elimination''' is a basic solving technique that primarily applies to Sudoku Variations with irregular groups of cells, such as Jigsaw and [[Killer]..."

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'''Common Peer Elimination''' is a basic [[solving technique]] that primarily applies to [[Sudoku Variations]] with irregular groups of cells, such as [[Jigsaw]] and [[Killer]] Sudoku, and (to a lesser extent) to [[Sudoku-X]]. It is based on the following simple principle:

"If a group of cells G is known to contain the digit D, then we can remove D as a candidate from all other cells that can [[see]] all candidate positions for digit D in group G."

Note: This technique is a superset of the classical technique [[Locked Candidates]].

== Example 1 (Jigsaw) ==

The following example is taken from [http://www.sudocue.net/jigsaw.php Daily Jigsaw] [http://www.sudocue.net/jigsaw.php?nr=13 13]. Note that there are three possible positions for the [[digit]] 3 in column 9: '''r1c9''', '''r2c9''' and '''r4c9'''. All three cells have '''r4c7''' as a common [[peer]]. Therefore, the [[candidate]] 3 can be [[eliminate]]d from '''r4c7'''.

[[Image:Cpe1.png|Common Peer Elimination example 1]]

== Example 2 (Killer) ==

The following example is taken from [http://www.sudocue.net/weeklykiller.php Weekly Assassin] [http://www.sudocue.net/weeklykiller.php?id=36 36]. The 27/4 cage at '''r2c2''' must be either {5679} or {4689}, and therefore must contain the digits 6 and 9. Both cells in the 9/2 cage at '''r1c3''' can [[see]] all cells in the 27/4 cage. Therefore, the candidate 6 can be eliminated from '''r12c3''', which must therefore contain the digits {27}.

[[Image:Cpe2.png|Common Peer Elimination example 2]]

== Notes ==
* If group G (see formal definition above) contains only 2 candidate positions for digit D, the same candidate eliminations can be caught by [[Simple Colors | Simple Coloring]].
* For [[Sudoku-X]], Common Peer Elimination catches all simple [[Crossover]]s.

== See Also ==

* [[Locked Candidates]]
* [[Simple Colors]]

[[Category:Solving Techniques]]
[[Category:Killer Sudoku]]
[[Category:Sudoku-X]]

Common Peer Elimination - Revision history

Rooted: Created page with "'''Common Peer Elimination''' is a basic solving technique that primarily applies to Sudoku Variations with irregular groups of cells, such as Jigsaw and [[Killer]..."