Here's an XY-wing that is not rectangular and has mutliple
target cells:
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The base is shown in blue,
the pincers are yellow and the target cells show eliminated 6's.
The 56 pincer in r2c6 is related to the base by box 2
instead of a row or column. When this happens, it is still
an XY-wing but it is not rectangular and there is more than one target
cell.
Even though we have two target cells in this example, there are
actually five potential target cells here. Just look at all of
the cells that are visible to the two yellow pincer cells:
r2c4 (eliminates a 6)
r3c4 (would have been a target but its already solved)
r7c6 (35)
r8c6 (eliminates a 6)
r9c6 (39)
So non-rectangular XY-wings can give you more bang for the buck than
traditional square or rectanglur ones that only give you one target
cell.
(This is similar to an XYZ wing)
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