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## Almost Locked PairFrom sudokuwiki.org, the puzzle solver's site |

This is a nice little pattern that is simple enough to be included in the Tough strategies section. Promoted by Gordon Fick on the New Sudoku Forum, his thread is here. The same pattern is discovered using more sophisticated methods down the list but I think is worth spotting earlier on. It is a "bent-set" and should be another Wing type in my opinion.

Two numbers

Looking along the row there is a bi-value cell C4 permitting only X or Y. Since X or Y must appear in that cell

As Gordon writes, the idea that C7/C9 must contain

The second orientation swaps the bi-value X/Y cell with the bi-location X/Y. Now the row contains the three cells meaning C7/C9 has at least one of X and Y (making it bi-location since it is a single cell C3 plus a Grouped Cell C7/C9).

Because the bi-value cell A8 must contain one of X or Y the Grouped Cell can have

This all of X and Y can be removed from the rest of box 3 and any extra candidates on C3 can be eliminated.

to do