A Tribute To Numberphile!

[@jasond4084]

I saw you on Numberphile. I clicked on it thinking it was a CTC video and to my delight WORLDS COLLIDED and for the ~400th time I patiently watched you prove the theory.

[@CriticalMonkey623]

This was absolutely my experience as well. What a delightful crossover!

[@peteralund]

And I finally used it to solve a sudoku, not a hard one mind you just an easy one to see if it works and it sort of did

[@ToroHarfang]

There have been a small handful of times over the past 5 or so years that two worlds I'm into have found their way to each other and every time it's like a high. So, so much fun seeing things I love merge. 💜

[@DaleKingProfile]

I feel that Simon makes it harder on himself by never removing colors. I think having 3 colors in r3c3 made it harder for him to see that it resolved the 45 in box 3

[@kathyjohnson2043]

I usually erase the color as soon as I can signifying that that logic is resolved.

[@electricnight6484]

Yes I was thinking that as well since Once I had the 2,4 in box 1 and 4 I had the 4,5 in box 3 giving the 5,7 in box 1 ... so I had many others sooner by using the zipper lines

[@louisng114]

Mark is better at coloring than Simon.

[@mentalcasanova]

Simon found a man who would absolutely be delighted to see him at a party. :)

[@kathyjohnson2043]

Others, including me, agree and I would love to talk to Simon at a party.

[@AyaAlef]

I remember one of the regular mathematicians on the numberphile channel, the wonderful James Grime (Singing Banana), saying in one of their earlier videos that he's not fond of sudoku puzzles because he enjoys using logic and creative deductions, not calculating like a computer or doing something with numbers a machine would be able to do (or something similar). I sometimes wonder whether he had stumbled upon your channel already and realized how sophisticated the logic required to solve these puzzles is. I'm sure he'd give it another try :) Anyway, Numberphile and CTC are a match from above! Two of my favourite channels, I loved every minute of it (and the bonus videos of course!). Thank you and happy new year ^^

[@olivier2553]

I came to CtC because of Numberphile (or Matt Parker) once mentioned this channel.

[@TwoEcksKay]

Sounds like someone who has only tried computer-generated puzzles.

[@Yttria]

It's definitely possible. After stumbling across this channel over 2 years ago, I started by watching Simon's solves and eventually started solving them myself. I had done normal sudoku puzzles in the past but never really enjoyed them and still don't enjoy the sudoku part of the varient puzzles. That said I love varient sudoku puzzles because of all the different kinds of techniques and logic required to solve them and it doesn't feel like doing the same thing every time.

[@AyaAlef]

I've found where he says that (hope I represented the general idea properly): kzbin.info/www/bejne/g53chaRjrbueh6csi=veQMq_E7CgT7ndiX Minute 8:05

[@electricnight6484]

I don't think James Grime ever managed to do any type of Variant Sudoku that is often on CtC => 0 numbers given but something else gives the clues. (I wonder what he would say about No Number Clue Sudoku like this one)

[@inspiringsand123]

Rules: 05:07 Let's Get Cracking: 08:56 Simon's time: 47m10s Puzzle Solved: 56:06 What about this video's Top Tier Simarkisms?! Bobbins: 2x (02:49, 44:43) The Secret: 2x (01:49, 56:08) Phistomefel: 1x (00:47) And how about this video's Simarkisms?! Beautiful: 7x (17:39, 18:16, 34:13, 50:36, 56:05, 56:05, 57:07) Obviously: 7x (02:52, 03:23, 09:54, 30:05, 30:25, 52:17, 54:33) Ah: 7x (14:34, 16:15, 16:37, 31:49, 31:49, 46:59, 54:02) Hang On: 6x (16:37, 26:28, 26:28, 29:43, 33:05, 56:33) By Sudoku: 5x (31:34, 40:30, 41:24, 46:28, 51:04) What Does This Mean?: 5x (10:37, 19:20, 22:10, 35:39, 45:13) Sorry: 4x (10:44, 23:13, 26:57, 48:41) Brilliant: 4x (02:01, 04:07, 18:18, 56:05) Pencil Mark/mark: 4x (23:46, 25:09, 33:09, 39:55) Surely: 3x (31:12, 46:40, 46:48) In Fact: 3x (03:45, 06:48, 39:38) Weird: 3x (29:04, 37:29, 56:56) Bother: 2x (33:43, 49:28) Naked Single: 2x (50:12, 55:52) Clever: 2x (17:42, 24:11) Bonkers: 2x (32:43, 32:44) Good Grief: 1x (50:46) Goodness: 1x (18:11) The Answer is: 1x (32:03) Nonsense: 1x (19:08) Stuck: 1x (35:58) Horrible Feeling: 1x (36:12) Lovely: 1x (57:22) Gorgeous: 1x (18:37) Take a Bow: 1x (57:09) We Can Do Better Than That: 1x (34:58) Phone is Buzzing: 1x (10:44) Next Trick: 1x (55:08) That's Huge: 1x (26:57) Nature: 1x (33:59) Cake!: 1x (04:58) Serendipitous: 1x (07:17) Most popular number(>9), digit and colour this video: Twelve (21 mentions) Two (82 mentions) Purple, Blue (5 mentions) Antithesis Battles: Low (2) - High (0) Even (14) - Odd (9) Row (10) - Column (9) 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!

[@Ryan-oq8gy]

My friend you are the #1

[@stclark278]

You forgot to add the using ridiculous logic as a work around for straight forward logic…when busts out the AB pair but the vertex of that line has to be a 3,6, or 9 due to region sum and you can rule out 3 and 9 with his existing pencil marks. He should not be able to get away with this stuff!! Lol!!

[@Dad_Jokes87]

I had the pleasure of getting to test this puzzle in preparation for Secret Santa. I'm so glad this one got a feature. Great solve Simon!

[@kennetsdad]

Yes you did!

[@livmakes21]

Really nice explanation in the numberphile video! Glad to see a collab :)

[@HunterJE]

Since we're in a Numberphile mood here's the algebraic version of the relationship of digits on the 4-line and the 5-line with its center at r3c4, which I did to convince myself of that relation and which Simon works out by more sudoku-ey means at ~30:40. Pretend I'm writing this on brown paper with a sharpie. Label the non-center cells from end to end A, B, C, and D. By sum line A+B=C+D, while by zipper A+D=B+C. Rearrange the sum line equation to A=B+C-D and substitute in to the zipper equation to get B+C-D+B=C+D, which works out to B=D. Subbing that in to either original equation gets you A=C.

[@electricnight6484]

I often use Algebra to solve some of the CtC puzzles that Simon does in a different way => I guess that's why I often prefer placing Letters rather than Colors

[@patrickgass787]

Speaking from experience, there's a lot of fun to be had exploring the combination of Zipper lines and other lines; they each have their own unique set of restrictions to discover.

[@electricnight6484]

zipper rimband?

[@kennetsdad]

"Tell him it's a think piece about a mid level band struggling with their own limitations in the harsh face of stardom." Thank you for the feature, Simon! Great explanation of the mathematics.

[@cathybryant5119]

25:31 for me. My brain seemed to grasp the math of the lines quite easily. I found the puzzle absolutely lovely and smooth.

[@anaayoung9142]

Super nice puzzle with a amazing logic. Could not be able to do alone. Enjoy watching your solve! Thanks for it 🤗

[@chocolateboy300]

I finished in 50:02 minutes. The combination of these rulesets makes for some fun math calculations in my head. I really enjoyed calculating it all. I think my favorite part was knowing that r3c4 had to be a 6 due to the interactions on the zipper to the left of it. Great Puzzle!

[@KittSpiken]

What a pleasure to see you conversing with someone who would find you fun at parties.

[@longwaytotipperary]

See there!! We all told you that you just need better companions to party with!!

[@kathyjohnson2043]

I would absolutely be one of those people.

[@R..O..L]

Can confirm the books have arrived and are looking lovely. Now I just need to get over my hatred of writing in books (which I really should have thought about before backing the Kickstarter) and get cracking with them. I also had the time to try out the puzzle before watching the video for once - such satisfying logic required to resolve the lines.

[@leporid257]

see through paper like baking sheets, or more resourceful a dokument bag/clear foil? when i borrowed a friend's sudoku book i copied everything into a checkered notebook though.

[@Anne_Mahoney]

You should also have received a link to a downloadable PDF. Or you can use the links in the book to go to Sven's Software and print the puzzles from there -- I do that all the time.

[@davidrattner9]

Great solve from you Simon with sublime deductions all over in determining each line.

[@gordonglenn2089]

I really appreciated the color change at 42:45 It was driving me crazy [ever since the same story in boxes 1 and 4] to not make the color-number match more obvious. It is always interesting to see how two minds can look at things differently. Another example is how Simon was talking about the total sum of each line, while I was talking (to myself) about the value within each box instead. That different way of working with (related) number facts was also present in another recent puzzle that he solved. Viva la difference?

[@stephenbeck7222]

And it was the completely superfluous orange and green remaining in box 1, along with the mostly superfluous red and blue, that blinded him to the 4 that was disambiguating at the end for him.

[@livedandletdie]

It was a nice Sudoku, a bit mindboggling but an absolute enjoyment to solve. And It was also absolutely enjoyable to watch Simon struggle with simple stuff as always, but somehow finding the break-ins like it's no problem at all...

[@Sam_on_YouTube]

46:51 Beat Simon's time by a 19 seconds. Very happy with that.

[@praematura]

Loved this puzzle, nice challenge, and completed in 21:40 (conflict checker off). The heavy math in this one really worked in my favor. 🙂 Many props to Kennet's Dad for a very cool puzzle!

[@Yttria]

Congrats on the Numberphile appearance! Really enjoyed this puzzle and initially thought it was going to be difficult. Turned out to be approachable with unique logic. Solved in 29:33.

[@martysears]

Such an elegant puzzle. Can't believe that solved with only 6 lines and nothing else

[@adamhunter1223]

I said this over on the numberphile video, but I think it bears reiterating: This is the turbonerd crossover we never knew we needed.

[@shadeblackwolf1508]

I kinda did this opening in reverse, studying the length 5 lines first... concluding that they needed 2 ways to make teh number, adn the sum of differences had to be the same as the center digit because the center digit had to be squeezed in on the low half of the line. A little playing around showed that the sum of 2 differences in this puzzle is always even, and all of them are set up such that you need 3 ways to make the total, can't just repeat digits, so all of them had to have a 6 or 8 center. then the line setup 2-1-2 in the upper left helped disambiguate some of that. then from there i went to the big line, completely missed the multiple of 12 requirement, and went through a painful elimination process until i found that box 6's component maxed at 12 and box 8's minimized at 12. It was painful, but it worked.

[@titusadduxas]

1:06:25 - Phew! It took me ages to get the rather lovely break in, but after that it flowed beautifully. Lovely puzzle.

[@markp7262]

25:19 finish. A very nice puzzle with some fun math logic. Excellent!

[@srwapo]

44:22, got there in the end, but remembering both rules and doing the math took a lot of work from me. Yes, I did write out equations to figure out the lines at the beginning. Like x+y=2z and x+z=y, solve.

[@johngranahan6102]

Great collaboration choice

[@dangrene617]

Loved this puzzle! Very fun playing with the possibilities. 21:31 solve time.

[@hughsherlock8916]

I tried to do this before watching Simon's video. I started with the lefthand zipper and used algebra to break it down where each unit was represented by its own letter, starting with "a" at the top of the zipper and going down to "e" - the centre point being represented by "c". So, what we know is.... a+e=c b+d=c and also, a+b=c+d+e. We can then substitute the second equation's value of "c" into the last, making.... a+b=(b+d)+d+e which equals 2d+b+e. Then minus b from both sides you get... a=2d+e. Use this value of "a" in the first equation and you get: 2d+2e=c or c=2(d+e) This tells us C is an even number and is either 6 or 8 (the lowest values of d and e being 1 and 2 and 2(1+2)=6); d and e have to contain a 1 and then either a 2 or a 3, and therefore a and b have to contain 5 and then either a 4 or a 7. This same algebra also applies to the other two longer zippers touching the outside of the grid. The zipper with its centre in the bottom left corner of box 2 is next. Because the centre is in its own box, the two legs have to contain the same digits (otherwise they would never have the same sum). I'll not go through it because it would take too long but if the centre of this zipper was any number apart from 6 it would break the deductions already worked out for the lefthand zipper. The only numbers possible on the legs of this next zipper, without breaking the other zipper, are then 2 and 4. d and e on the first zipper therefore have to be 1 and 3 making the first zipper's centre digit 8, the zipper along the bottom also 8 and the zipper the furthest right 6 by sudoku. This might seem like a convoluted way of doing it but I'm sharing because I found it incredibly satisfying to do and I've never applied algebra to a sudoku before!

[@ilsekleibscheidel7219]

this was also my way to start. But Simon's cosidering the factors of the regional sums is very elegant and could have shortened my way.

[@piarittersporn]

Brilliant puzzle.

[@DanielTaber-p7f]

The naked 4 in box 6 was driving me nuts, lol

[@ariwizzard]

36:58, lots of fun on this one!

[@bradleyreed8876]

Great puzzle and a great solve. Thanks!

[@craigthorsen]

Fun to watch the solve. Thanks

[@lasagna312]

23:26 After looking at the length of the video, I almost didn't try this puzzle. Turned out to be way more accessible than I thought.

[@psiphiorg]

Very mathematical indeed! I enjoyed solving this, and then watching Simon's solve. My time was 47:03, and I was solver number 1060.

[@Gonzalo_Garcia_]

14:17 for me. Very nice puzzle!!

[@StefanCM15]

First time i came close to your time.

[@markp7262]

@@StefanCM15 I've beat his time less than five times ever. Each time I finish a puzzle and scroll down the comments, thinking I had a good time, I reach this point and usually sigh. 🤣🤣🤣

[@BleachWizz]

0:55 - haha indeed, I didn't realized it was you who were there xD.

[@jussikuusela7345]

Damn it, I had to look twice and then once again... Simon striking a JG expression in the thumbnail.

[@six_5000]

46:55 I was doing fine for a while but for some reason my brain forgot all the rules by the time I got to the last line

[@robert-skibelo]

Wonderfully clever puzzle. Not one of Simon's better solves -- embarrassingly many bungles and oversights.

[@waterleau1486]

So simple ideas but executed with elegance. Enjoyed it a lot. (Comment by a math teacher)

[@AnastasiiaTishina]

well that was a delight

[@leredrasscul]

I little blind here, Simon. Jolly good

[@bait6652]

Surprising simple when u discover u can write equations....had to do a triple check to see what i was seeing. I dont like set repl much but eqns....fun stuff

[@dkamm65]

Does anyone know when they're doing the video shoutouts for the highest tier backers for the CtC book? Or did I miss it somewhere?

[@debrawilden1971]

(Pst-Has anyone mentioned this? Is there a way to make the lines less thick or intense? It's very hard to see the digits on them, especially when they are only candidates. Thanks for the consideration.)

[@debrawilden1971]

(I see that the setting of 'outlines on elements' helps, but I generally don't use that feature since it's harder to the candidates when there are no lines.)

[@andrewdipplecomedy]

At 42:10 - can someone explain why 8 wasn't an option for B? I'm really struggling to figure it out 😔

[@alcaz0r1]

It's because B is restricted to two places in box 1, and 8 cannot go in either of those places. Another way to see it is to look at where 8 can go in box 1 - it has to be in row 1 or row 2, and if B was 8 it would put 8s in both row 1 and row 2, but outside of box 1.

[@anomalousresult]

Think the harlequin coloured 4 was camouflage.

[@ronjohnson6916]

Fortunately I don't think those bad 9 pencil marks in box 7 will hurt.

[@alanboyle6751]

They’re hurting me

[@isakoolsson]

Bought the first book, looking forward so much for this next one 🫶🏼

[@michaelandersen-kk4fc]

he clearly messed up 9, in box 7. shouted so much

[@maxbrouwer95]

24:20 for me

[@TiagoMorbusSa]

ha, bifurcation town, we meet again

[@57thorns]

I think Simon has a tendency to give up on Sudoku way too early,. Me on the other hand ten to pencilmark so much I can't see the logic of course. But in this case, 57....

[@57thorns]

And Simon using the same colour to denote different digits while the same digit has another with A or B in it is rather confusing. Not once, but twice...

[@57thorns]

At 43:10 I think looking at the columns makes it easier to see that pink has to be 1, 2, or 8.

[@dpatto]

I'm not sure how the orientation of the digits for line 1 worked. It seems they could have been reversed (at the time of placement), with the 1's in box 1.

[@HunterJE]

By the zipper rule, yes, but not the region sum rule.

[@dpatto]

@@HunterJE Of course, it's obvious! Thanks.

[@joelstevens5670]

When zipper and sum rules combine, You’re left with a wonderful line, For one cell or a pair, Gives the values elsewhere, While the rest the box regions define.

[@sirlionel3285]

Spotting the naked 4 in r4c7 would have helped quite a lot by resolving most of the lines. But spotting naked singles isn't exactly my forte either, so i'm not judging

[@leporid257]

their puns about this on valentine's days might always be my favourite

[@nicka3697]

I find your videos so useful. They do 5 things for me: 1) get me started when I hit a block 2) sort me out when I make an error 3) teach me new techniques 4) entertain me with songs or poetry or heartfelt sympathy and just a lovely personality.

[@amoswittenbergsmusings]

Apparently they also stop you reaching 5 when you make a numbered list 😄

[@Moolers]

Somebody showed me that Numberphile video because they know I love sudokus and I said "hey, that's no secret, I've been using that trick for years thanks to CTC" 😄

[@erlandodk]

Simon's surprise at having to do sudoku while solving a sudoku puzzle never fails to delight me 😁

[@Sandra_and_Nala]

It really was interesting to see you from a different perspective in the numberphile „feature“ 😄 and I love that the comments instantly picked up on this!

[@longwaytotipperary]

Yes! I enjoyed seeing the different perspective ( finally proof you are more than a “talking head” 😁 ) and seeing you in a well lit, more spacious room!

[@davidrattner9]

​​@@longwaytotipperaryloved that to..seeing him in a different environment!! Hope you are feeling better from yesterday and cozy blanket and tea did wonders for you.

[@longwaytotipperary]

@@davidrattner9 definitely better today! Thank you! 🙂

[@joelstevens5670]

Ok. How and I mean how do people come up with things like this? The logic is somehow both stunning and mind-bending at the same time. Utterly brilliant and Simon’s solve was just as impressive. What a week of puzzles.

[@peteonretreat2023]

Man… I love watching Simon solve sudoku puzzles so much!!!

[@MelissaW09]

Guysguysguys! I didn't need help with the break in! I didn't even watch the rules! I officially did a puzzle completely on my own! ...okay, it's not my first, but I feel like I ram my head against walls until it releases its secrets sometimes, and this one was just... so beautifully smooth. And I don't usually like the maths! And I solved it under an hour! A very distracted hour! 💃 💃 💃 Edit: oh, I started completely different too. This is such a cool puzzle. Thank you Simon!

[@alanscott8245]

Finished this one in 32:49. Not often that I beat Simon's time, but the math logic of those lines was lovely and easy for me to grasp.

[@TheHonorist]

If he saw the single digit in r4c7 at about 28:24 it could have saved him plenty of time. But I like to see him doing crazy stuff instead of "easy" solutions 😅

[@ingvarsuigin609]

at 24:00 "Let me just pencil mark 9 in the same row as an existing 9, instead of the row above" a small funny misstep.

[@bradleyreed8876]

Then penciled three more 9's in the same box later and saw nothing wrong with five 9's penciled in.

[@wossaaaat]

Yup, my copy of the book arrived wednesday. Thank you! Btw, only 2 l's in you'll... 😜

[@derekjc777]

Got my books today! I was surprised because I didn't expect them because I didn't know when they would arrive, but they're here now.

[@longwaytotipperary]

Hope my book comes soon!!

[@davidrattner9]

​@longwaytotipperary coming soon for me. Saw the delivery status update. At a usps facility by me. 🙂

[@longwaytotipperary]

@@davidrattner9 oh wow!! 🤗

[@blacxthornE]

I was so glad to see you at Numberphile! Worlds collide!

[@Paolo_De_Leva]

The interactions between the *5-cell long* lines are amazingly powerful, and unfortunately Simon was *so smart* that he did not need to use them all‼ (their "arms" interact in box 4 and columns 2-3; their centers in row 4 and column 4). I think Simon was *👉too much👈* "smarter" than me. He started from what was for me the most difficult line (the longest one), and was able to reach that genius conclusion about the two possible positions of *6* along that line. As a consequence, however, he missed some of the "dumber" logic steps that I enjoied (including one of the above mentioned beautiful interactions). He was so smart that he was not forced to start from the easiest line (the top left one). I started from there, learned how it worked, easily deduced the value (8) of its center cell, and then used similar logic for all the other short lines before analyzing the longest one... *In short,* my logic path was more gradual, less awesome, less powerful, but *equally fun.* 🤪

[@Paolo_De_Leva]

By the way, I do not like "mixed" notation. For instance, @31:14 Simon uses letters together with colours. Also, center-pencilmarking *246AB* in box 7 is ok, it works, but I do not like it. A simpler and more familiar notation uses *blue* instead of *A* and *green* instead of *B.*

[@electricnight6484]

@@Paolo_De_Leva -> IDK i like the Letters vs the Colors I realized early the box 1,2,4 line box 1 A,B,box 2 (A+B) box 4 (A,B) I also saw the box 1,box 4 line matched vertex of the Box 3 Box 6 line => that gave me 6,8 there with 123 in box 4 and box 6

[@msbuck007]

I know I probably miss things all the time, but I have been hitting my head against the wall when you did not fill in the naked 4 in quadrant 6 at 28:21 and only fill it in 20 minutes later.

[@tabris1135]

For the 4 long line: let r3c6 a r2c6 b r2c7 c r1c7 d a+b=c+d and b+c=a+d a=c+d-b and a=c+b-d So c+d-b=c+b-d Thus d-b=b-d From this follows 2d=2b and therefore d=b, thus proving without a doubt that the logic applies

[@karlmortenlunna2417]

19:01 for me. Very interesting puzzle!

[@emdiar6588]

A five year old - "two plus two is four" Simon - "We have to make an even number (A) using a 2 plus another even number which we'll call B, which doesn't bring the total (A) to more than double the given 2 (2A) - so I think that B must be between 1 and 3 and A is between 3 and 5 - I don't know - A might have to be 4 - not sure about that - what else is there? - What am I missing? - I wonder if it's Sudoku..."

[@SmarkusAurelius]

33:32, very rarely do I beat Simon. Proud of myself on this one

[@andremouss2536]

43:20 Simon must be joking ! 'Some kind of pressure that I can't foresee ?' Obviously A can't be 2 3 4 5 6 7 9 !

[@MeriaDuck]

At some point around 42:30 or thereabouts, B had to be chosen from {1,2} and {1, 3, 9} which only have 1 in common. Or were those Bs not the same!? They turned out to be in the end... I was quite confused that you did not use that, Simon. 🤔

[@BenFromOhio]

Thank goodness for the KZbin preview screen on the timeline so I knew how long I would have to tolerate the misplaced 9 pencil marks XD

[@asherhiggins7853]

I got it in 45:52. Started off with some pen and paper algebra to pencil mark the three 5-length lines, then used deduction to find two reasonable [overlapping] solutions to the 7-length line. The rest was basic.

[@JohnRandomness105]

23:50 The heavy Sudoku comes later. Now go to the other lines. 29:50 It appears that I made a very lucky blunder when I did that colored line, before any line except the longest. I got the unwarranted idea that the sum cell had to be a multiple of three. Of course it doesn't have to. I was lucky in that it was 6, and my blunder never returned to bite.

[@Hedning1390]

23:47 this could easily have caused ruin. So dangerous marking false numbers.

[@stangerrits6712]

28:00 Great to see you avoiding confusion here, by just not seeing or ignoring your erroneous 9 pencil marks that were already in box 7 😅

[@JalebJay]

23:51 took me a moment to realize what to do with the lines. Using overlap with lcm resolved it for me.

[@AdamDesiles]

Don't you just love when a naked single 8 solves your puzzle

[@lapetitecuillereetlepaindo3005]

30:56 for me. Algebra is one of my better sudoku tricks.

[@evanbasnaw]

Can't wait to watch the Rollercoaster video

[@magnuspahlsson3531]

At 27.40 you have a naked single 4 in box six!

[@Rach881101]

45:30 for me. Interesting puzzle!

[@ericpraline1302]

Interesting ruleset, thanks.

[@林老師-i5d]

35:05 for me nice puzzle

[@mxpxorsist]

22:04 for me

[@davidblake6889]

That was a very good puzzle, thanks. The solve was excellent as usual, Simon. But I do feel that if you leave the colouring in the grid after it has served its purpose, it seems to prevent you seeing the numbers in the coloured squares. The 4 in box 1 was staring at the 45 pair in box 3 for ages before you spotted it.

[@electricnight6484]

which would have definitely cascaded around the puzzle much earlier solving the zipper in Boxes 1,4 and 3,6 that made for me the box 2-3 zipper easier to solve

[@specialkalberta]

I hope my book comes if I ordered it and paid for it. But I'm not sure if I did.

[@ckdo1974]

@36:19 -- Here's some of the sudoku staring Simon in the face: Column 3 is missing [13689], of which [138] can't go into box 4, revealing a [69] pair there, placing the 6 in box 5...

[@averygaron994]

I saw the numberphile in my recommendations and it was clearly about the phistomophel ring from the thumbnail. Didn't realize you were actually the guest! Very cool

[@gatlygat]

This is a delight of a puzzle. Very much enjoyed... got through at a good clip which was surprising, but also accentuated how cleverly it is constructed. Bravo!

[@chipsounder4633]

Excellent puzzle, the algabrae was elegantly used. Could imagine that with a yin yang rule and the 11x11 build your own regions (irregular) sudoku. We need a video longer than Titanic 😂.

[@cameronsooley5964]

saw at 22:00 that 5,7 could only appear in the 8th/9th positions in r7 making 8 invalid for the center of the top right line. Been having a conversation out loud with Simon for 5 minutes for him to see it LMAO