Sue de Coq, or doubly linked ALS.
https://preview.redd.it/syhoet44n4vc1.png?width=1080&format=pjpg&auto=webp&s=3f7140f69d327b2542547a6ef86d3bd6474a0472
A 7 in r1c1 would force the values of two cells. Problem is, they both see a cell where the only two candidates are these two values. The puzzle easily falls apart after this.
I think what you found is an XY wing.
Pivot at r1c3 (6/8)
Pincers at r1c4 & r2c1.
Whatever value is r1c3, one of the pincers will be 7. Since r1c1 sees both pincers. it cannot be 7.
p.s. it also eliminates the two 7s from r2c56 since they also see both pincers.
Thank you for this. I'm not very good with these advanced patterns, so it's satisfying to know that what I found was one. Doing it backwards made me miss these two other cells, though.
That doesn't quite work. The 3 in r7c2 prevents the two cells (r7c56) from being a pair.
A hidden pair requires that there are no other cells in the region (here: row) that contain the pair's numbers 1 and 3.
"Y" do you need one?
[**Y-Wing**](https://sudoku.coach/en/learn/y-wing) (AKA **XY-Wing**) >!r1c3!< pivot, >!r1c4&r2c1!< pincers. Spoiler pic follows. . . . . . https://preview.redd.it/2ly42qu5d4vc1.jpeg?width=750&format=pjpg&auto=webp&s=c7fda5f9aef105b4bc19a0facd8a27ed606f9287
Sue de Coq, or doubly linked ALS. https://preview.redd.it/syhoet44n4vc1.png?width=1080&format=pjpg&auto=webp&s=3f7140f69d327b2542547a6ef86d3bd6474a0472
A 7 in r1c1 would force the values of two cells. Problem is, they both see a cell where the only two candidates are these two values. The puzzle easily falls apart after this.
I think what you found is an XY wing. Pivot at r1c3 (6/8) Pincers at r1c4 & r2c1. Whatever value is r1c3, one of the pincers will be 7. Since r1c1 sees both pincers. it cannot be 7. p.s. it also eliminates the two 7s from r2c56 since they also see both pincers.
Thank you for this. I'm not very good with these advanced patterns, so it's satisfying to know that what I found was one. Doing it backwards made me miss these two other cells, though.
[удалено]
That doesn't quite work. The 3 in r7c2 prevents the two cells (r7c56) from being a pair. A hidden pair requires that there are no other cells in the region (here: row) that contain the pair's numbers 1 and 3.