A Tough Proposition? Or Not?

Normal sudoku rules apply. Digits along thermometers must increase from the bulb end. A clue outside the grid shows the sum of the digits along the indicated diagonal. These digits may repeat if allowed by other rules. Adjacent digits on a green line differ by at least 5. Cells separated by an X contain digits summing to 10. Cells separated by a V contain digits summing to 5. Cells separated by a white dot contain consecutive digits. Not all possible Xs/Vs/dots are given.


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▶Credits◀
Music: Tim McCaskey (Guitar) or Lucy Audrin (Piano) or Riffclown plays Mozart's Sonata no 16 ("Sonata Facile"), and Mark’s outro music by Riffclown.
SOFTWARE: Thanks to Sam Cappleman-Lynes and Sven Neumann for their work.
Logo: Melvyn Mainini

Opening Credits: Joel Blundell

▶ABOUT US◀
Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.

Thank you for watching!
Simon and Mark

[SheilaMertens]

Thank you, Mark. Managed to solve it in about 60 minutes, without help and that's rare, really liked it. Love, Sheila.

[danielcamp]

Wow! I really loved this puzzle. It fell right in my sweet spot of being challenging enough to be fun but not too difficult so as not to be enjoyable. Great job!

[berlinflight_tv]

45:12 for me. What held me up where two things: I needed 10 minutes or so to realize that cracking the high-low order was key and another 10 minutes to figure out how the diagonal 9 clue helped me with that. After that it was smooth (albeit still slow) sailing. Happy that I managed to figure it out by myself, though.

[xaviarthunders]

Mark, I prefer these faster solves by far. If I can't understand a step in the logic I can pause ... so please consider this pace as your solving style. Its honestly a very satisfying viewing experience.

[erinleeann]

10:45 for me. I always love sudokus that involve XV rules and thermos, this was a really fun puzzle!

[longwaytotipperary]

I had to look up the definition of recherche (as well as spelling). I learn more than sudoku watching Mark and Simon. Always amazed at Mark’s extensive knowledge and vocabulary.

[Ruotiukk]

At 12:08, the digits 3, 4 and 5 form a triple because we have the third digit (3 or 4) from the X clue in addition to the 45 and 34 pairs.

[sillyking]

about 37 minutes for me. that was actually a lot of fun. i enjoy the ones that are semi easy like this definitely an interesting setting

[gposchman]

In box 4 when you were setting the colors on the whisper line, column 3 had 3 high digits in it already, which means the single color had to be the high digit. That is how I found it, and I learned that from you guys. Thanks so much, it was a great puzzle.

[tremkl]

There was a point where I considered using uniqueness and I’m glad I didn’t, because it turns out it WAS the deadly pattern which got resolved by a diagonal. 21:19 for me. Fun puzzle.

[davidh.]

34:27. A bit slow, I feel, but I did go all out on hi/low coloring, which ate up a couple of minutes. I also had to course-correct when I started treating the thermos as arrows.

[nickatty]

I made that far more work than I should have done by doing a lot of clever stuff on the left hand side before noticing what could be done in box 9. But that did mean that from then on it flowed very nicely indeed.

[trevorwright]

A throughly enjoyable puzzle, many thanks to Igor for constructing this. Loved it. Much prefer something mere mortals can have a go at compared to monstrous break ins that kill a puzzle at step 1.

[jacobcombs]

19:47 - Only 57% slower than Mark, I treated the entire puzzle as a high low puzzle the whole way and it flowed well enough for me. I was able to get the polarities largely fixed in boxes 1 4 7 and 9 pretty darn fast because of the way the clues were set. That led to box 8 and I just kind of worked my way out from there. My finish time includes marking every cell as either blue low red high or purple fives.

[emilywilliams]

Very nice puzzle and solve, Mark. I did give it a go myself and completed it. Not in GAS time for me, but in acceptable time. (Good thing I'm not going to the World Championships, that is clear!) I appreciate that you have pre-recorded videos so that we don't have to miss out on seeing you every day, solving these lovely puzzles and giving us your wit and charm. I have been able to follow along on the WSC results page somewhat. (You never need apologize to me for "rushing." I love to watch you solve at any speed.) Congratulations on the channel debut, Igor!

[inspiringsand]

Rules: 03:08
Let's Get Cracking: 04:40
Mark's time: 12m37s
Puzzle Solved: 17:17

And how about this video's Simarkisms?!
Ah: 5x (07:49, 09:02, 11:40, 13:08, 14:51)
Brilliant: 3x (00:37, 00:48, 00:50)
Sorry: 2x (01:07, 14:04)
Approachable: 2x (16:57, 17:19)
In Fact: 2x (10:02, 15:46)
Naked Single: 1x (15:40)
Nonsense: 1x (07:24)
Lovely: 1x (09:28)
Fascinating: 1x (02:08)
Deadly Pattern: 1x (17:04)
Hang On: 1x (11:45)
Surely: 1x (16:01)

Most popular number(>9), digit and colour this video:
Ten, Thirty (3 mentions)
Three, Five (37 mentions)
Purple (7 mentions)

Antithesis Battles:
Low (15) - High (9)
White (6) - Black (0)
Column (5) - Row (2)

FAQ:
Q1: You missed something!
A1: That could very well be the case! Human speech can be hard to understand for computers like me! Point out the ones that I missed and maybe I'll learn!
Q2: Can you do this for another channel?
A2: I've been thinking about that and wrote some code to make that possible. Let me know which channel you think would be a good fit!

[nimbletim]

21 minutes! very fun. the not so deadly, deadly pattern at the end scared me for a sec.

[flobiish]

@12:55 I noticed a slightly easier way to disambiguate this part of box 1. The 9 in box 1 has yet to be pencil marked, but if it were, it would be on the white dot, necessarily with an 8. Putting the 7 in r1c1, plops a 3 on the X and the 2 and 6 in as well from the pencil marks. I don't think it would be faster to do or explain, but I think the logic is easier to spot.

Nice puzzle. Good solve. As always, very enjoyable.

[CptRyaffio]

I got a deadly pattern at the end, thought I had a logic error, started over, got the same result and then realized I'd forgotten the killer clues outside the grid! In the end I only needed the 30 clue, btw

[pianissimo]

The 2 in box 1 was the hardest number. Its a bit hard to spot but if you can, it should be considered GAS.