Thank you so much Simon. The way you walk through the puzzles step by step really brings the strategies home for me. Teaching in context. So good. Did my first swordfish as a result of this CTC!

Actually in the first puzzle there is another XY-Wing (after swordfish): 267: r1c2, r2c1, r2c6. It eliminates the 7s in r1c56 which immediately gives us a 7 in r2c6 and a 4 in r1c5 and the nthe whole second square.

I had to watch this several times to understand it. It helped me solve a difficult puzzle. Thank you.

I've never understood swordfishes but in this example it looks like an X wing in blocks 3 and 6 with a horizontal and vertical one attached. Thanks Simon.

Thank you for such a clear explanation!

it seems a difficult thing to spot if you dont use full notation

I can apply XY Wings, 3 linked color chains, and swordfish techniques, but I have an incredible amount of difficulty spotting them myself. On Andoku 3, these techniques are intrduced in the "Hard" tier of puzzles, and I usually find myself at a point where I have... about 30 or so squares left to fill in the puzzles, and all the pencil marks filled in, and I wind up flailing blindly from any 3-cell combo of 3-4 candidates with 2 candidates per cell I can find ("Hey, there's a cell with 56 candidates, a cell with 1 5 candidates, and a cell with 16, and a cell with 1 candidates, and look, the 5 or 1 or 6 has only two candidates in this house... maybe this will work. " And then a minute later I realize it was a dead end all along and I start scanning again, hoping to stumble upon a different chain or wing that bears fruit. For example, in the puzzle at 7:12, my eyes immediately went towards columns 4 and 6 - the 34, 14, and 48 cells. If I were solving this puzzle myself, on my own, I probably would have started pencilling in the remaining candidates in subgrids 5 and 8, then and moved to subgrids 6 and 9. I guess I just have bad intuition for these things since there's a bit of a spacial component to them, rather than mere set logic. Do you have any advice on getting better at them?

Thank you for this lesson, it's very clear and helpful!

Thanks so much! FINALLY understand the Y-wing technique.

Your Y-Wing in the first puzzle also eliminates the 2s in D1 and F1, forcing a 2 in D2.

Helpful, thanks I call Y wings ‘bent triple’ as that helps me remember them more easily But I realise I have only been looking for right angle versions, whereas I should be looking for more variations / 2 in a box

I’ve worked sudoku puzzles for years. I NEVER have been able to find an XY wing. Apparently there’s something I’m not picking up on

There should definitely be a CtC history channel - this video looks so vintage in 2022. What a difference to nowadays.

Thank you Sir

Thank you Sir ji

Can you eliminate the 7 in row 1, column 6, if you use the 2-6 as the pivot, and the 2-7 and 6-7 (found in box 2) as pincers? I paused the video and that was the xy wing I found, so I was a little confused that there was another xy wing as your example!

I have a question. In the last puzzle you show, there is a 4-8 pairing in column one, and a 3-4 pairing in the same square right, square 7? In column 2? So, could the 4-8 and 3-4 pairing from square 7, columns 1 and 2, be in a Y wing with the 3-8 pairing at the top of column 2? In other words, could the y wing be in columns 1 and 2 or does it have to be in columns 2 and 3, and if so, why? Cheers. :o)

7:10 3 cells, 2 digits each. 3 unknown digits in total . Pivot is the one that look at the other two.

Wait. I'm having a hard time understanding why the 4 needed to be eliminated. When I look at the green triple, it seems that since 2 can't be in column 5, then there has to be a 2 in one of the other cells in the triple. And any of those 2 positioned would eliminate the 2 from the cell in columns 1 Is my reasoning mistaken or did Simon simply missed this reasoning?

9:00 COuldnt the right cell be the pivot? 3 and 4 can see all others

Does every puzzle have an XY wing? I've gone thru a hard puzzle and only kept the cells that have two numbers and I do not see an XY wing.

I tried my hands on the last puzzel, but I cant solve it. I get stuck with thousend pencilmarks and only 7 singels entered so far. Its been 2 weeks..... I think I need help. I tried it various times with either 3 or 8 in r1c2 and it just seem like it doesn't work. I feel so stupid and frustrated

Before you even start, in column 6 / row 2 how did you exclude the 2? Column 7 / row 2 how did you exclude the 4? And Column 7 / row 4 how did you exclude the 4? I just don't see it.

What music in the intro?

My Brain hurts ^^

I feed dumb because i just don't get the logic... I thought i was good at soduku.

dont use green

Is anyone else here in their 20s?

The voracious shrine partially whine because need complimentarily whip about a agonizing lawyer. wooden, hapless creditor

Can't hear a bloody word he's saying