dxSudoku #35 XY-Wing Puzzle Solving Technique 

The kill-zone is just a set of cells defined by the puzzle-solving technique. The reason I use it is because in the video, before I remove any candidates, I like to talk about "target candidates" which is the lead in for the discussion of the logic for how the puzzle-solving technique works. It's a little bit like an the Escher print of hand drawing a hand. I think understanding the puzzle-solving techniques in terms of sequences of logic is much better than just pattern recognition.

Thanks for nice comment!

Of course, good point! People often call the XY-Wing a "bent triple."

Glad you liked it!

Thank you! Cheers!

Yes. I find XY-Wings all the time with no target candidates to kill in the kill-zone created by the two pincers. You just keep looking. I find going from left to right top to bottom helps me from repeating the same search. Let me know if you have any other questions. Rock on!

The 69-R1C3-Pivot with 29-R6C3-Wing1 and 26-R1C8-Wing2 do form an XY-Wing. The kill zone would be the intersection point of the two wing cells which has the number 3 as a given. But the three cells do form an XY-Wing. When I created these practice exercises there could be more than one solution. If you are interested in creating your own practice exercises check out this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-jPssW_W3iH8.html

With the XY-Wing, the two pincer cells create the kill zone. Since R2C8 does not share a house with R4C2, the short answer is no. The kill-zone for the XY-Wing is any cell sharing a house with both pincer cells, R1C7 and R4C2 in this case. However, the better way to convince yourself of something like this is first pretend the pivot cell R1C2=5. Then pretend the pivot cell R1C2=6. In each case, R1C2=5, and R1C2=6, what happens to each pincer cell R1C7 and R4C2 ? This idea of pretending a cell is set to a value is key to doing logic with advanced chaining sequences. The XY-Wing is in a sense a type of chaining sequence with the way the logic causes a sequence of consequence.

It looks fine on my end. Maybe your network speed is slow. Does it happen with other RU-vid videos? What does Speedtest.net say your download speed is clocked at? www.speedtest.net/

@@dxsudokuchannel Hmmm.. I'm on RU-vid all day long. Never encountered this before. Thanks for the prompt attention anyway. I've removed the down vote.

@@fishloh97 I don't understand why you are seeing it blurring. What did speedtest.net say was your download bandwidth?

@@dxsudokuchannel Hi, bandwidth abt 40. Video image cleared up; not sure what happened earlier. Sorry about the trouble. My apologies.

@@fishloh97 No problem. I'm glad it's good now.