The New Sudoku Players' Forum

[Phartinoogan]

I came across this nice little pattern today after a little experimentation:

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--------+--------+------
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 . . 47 | 45 . . | . . .
 . . 57 | 45 . . | . . .
--------+--------+------
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Basically, the 45 pair up there cant be r5c4 = 4, r6c4 = 5 due to the fact that there would end up being two 7's left in c3.

This is relatively simple considering the level of solving used here, but I've never seen this particular technique addressed directly before. If it doesn't exist (as far as you guys know, anyway ) I would love to give it a name.

[Myth Jellies]

This is commonly referred to as an xy-wing. It is also a simple example of the Almost Locked Sets xz-rule

[tso]

As Myth says, it's an xy-wing, the shortest possible example of forcing chains. The fact that there is a [45] pair is a red herring. All values of r6c3, r6c4 or r5c3 imply that r5c4<>4. Any other candidates in r5c4 are irrelevant.

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 . . .  | .  . . | . . .
 . . .  | .  . . | . . .
 . . .  | .  . . | . . .
--------+--------+------
 . . .  | .  . . | . . .
 . . 47 | x  . . | . . .
 . . 57 | 45 . . | . . .
--------+--------+------
 . . .  | .  . . | . . .
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