Most days this doesn't even occur to me, which just goes to show how expertly you do it, but it's pretty rare to see RUclips videos with no edits/cuts, especially on something such as this with an intro, a complete as-live solve, and then an outro. (Unicorn-related emergencies don't count as edits.) I imagine that's partly why so many people find this channel relaxing, because you're not hit with a jump cut every 3 seconds, it's like a long soak in a warm bath, whereas so many videos are like 100 buckets of cold water thrown in your face. I really appreciate that.
@@GunganWorks yes! It’s the human element. Especially over the course of this pandemic, humanity has seemed scarce, and yet he has found his own way to provide it online.
@@th.nd.r I fully endorse your endorsement! Simon and Mark are friends you can hang out with. The quirky humour and the profundity of the logic are truly addictive. This channel has become a constant companion during lockdown - which I am sure was not a picnic for most. They should be recognised as one of the very good things to come out of a miserable year. I would welcome a knighthood for them. Seriously.
If anyone else wants another channel that has a similar style of no cuts and one take filming. I recommend GothamChess, he's an amazing RUclipsr who posts almost daily and does all his videos in one take. He also does chess videos, which is another game that requires logical thinking and stimulates my brain in much the same way ctc does I do recommend checking him out
"some of you might mumble that I have no strengths" My guy, you're solving some of the most insane sudokus and puzzles, all the while explaining your logic in an understandable way, while some of us (including me) are still processing the rules
i've been trying all the puzzles featured on this channel for the past couple weeks (well only the ones with sub-45 minute solve times for simon), and today's was the first i finished without consulting the video for hints!
I'm impressed! Personally, I don't get anywhere close on my own. The best I do is occasionally to shout at the screen when I think I've seen something they've missed ... and half the time I'm wrong 😳😂 Have you tried creating a puzzle of your own yet? I'd recommend watching Clover's video about how she sets puzzles if you haven't. ruclips.net/video/IE1N6B6SHQA/видео.html Enjoy ... 👍
As part of my ongoing series of "variant solves" which I do totally on purpose and definitely not because I'm an idiot (cough), it turns out if you treat squares as containing only _odd_ digits, you get completely and utterly stuck.
21:13 "Prize Charlie" is the new "Chocolate Teapot". For those of you who aren't obsessed with cryptic crossword language word-play, "Prize Charlie" is a reverse portmanteau for the wartime British slur "Pusillanimous Charles Hunt". You take the the first letter of Charles, 'C', and you add it to the final 3 letters of Hunt, 'unt', then you gussy it up for a family-friendly broadcast, and you get "Prize Charlie".
Not clear what you meant. I know nothing about cryptic crosswords and English is not my native language. You clearly explained what "Charles Hunt" meant in that wartime slur (en.wikipedia.org/wiki/Portmanteau). An attenuated version of the slur would be something like "Brave C. Hunt" or "Brave Charlie" (where "C. Hunt" still means "weak and coward"). However, "prize" is a verb, isn't it? So, how can someone be described as a "Prize C. Hunt" or "Prize Charlie" (21:13), and how can "Prize" be the reverse of "Pusillanimous"?
@@Paolo_De_Leva Cryptic crosswords are very confusing, even for native speakers, so don't feel bad, I don't get this either. Cryptics use certain rules and leading phrases and gotcha's all in a totally new kind word logic game that I've never seen before. Look up cryptics on the CTC videos list, and watch Simon's walkthrough/solve of a cryptic. It's astounding the logic and stuff he comes up with. You can watch Mark's cryptic solves as well, he blazes thru them at lightning speed.
I really appreciate the explanation, I’ve wondered for months where Prize Charlie could come from… another impossible to guess british long-tailed joke!
Dear Simon after only being an amazed watcher for a few weeks now I finally decided to try this puzzle before watching your video and although it took me much longer to solve than it did take you I am proud to say I was able to do it and I wanted to thank you both for introducing people to the wonderful world of advanced sudoku!
This puzzle is a great example of GSP. Everything’s so symmetric, even including the numbers, that any time a 1 is placed, a 9 can be placed across the grid by the same logic. Same goes for 2&8, 3&7, 4&6. Only 5 is unaffected by another digit, although there are certain locations that 5 can be immediately ruled out of due to this.
Once you realise the puzzle is symmetric like this, is it cheating to fill in all the opposite digits straight away? or should you carry on using logic to deduce them like Simon did? I sort of feel that, for example, once you know there's an 8 in r7c1, immediately pairing it with a 2 in r3c9 would be taking a very sneaky shortcut.
@@afrayedknot81 I've just been reading some of the other comments and seen a lot of other people asking the same question - only to be told that you can't guarantee the entire puzzle is symmetrical! I wouldn't put it past a setter to sneakily swap a couple of digits at the end of the solve path to trip up everyone who thought they could get away with only solving half the clues!
@@DanFre40 That’s actually impossible (otherwise the puzzle has multiple solutions). There’s nothing in the rules that could possibly break the symmetry.
@@DanFre40 I pulled up an earlier version of the puzzle I thought had a non-symmetrical solution, and realized it was a broken puzzle, so I believe I was wrong about that. (It also used some short two-cell thermos instead of evens squares, so it’s possible there is a version that could work non-symmetrically, but thermos don’t exactly follow the 1/9 2/8 3/7 4/6 symmetry rules)
I really enjoyed this puzzle. It felt like after the deduction at around 10:30 and onwards, there were many places to pick at it and get results, so after that first challenge it was very fun. For example the 1 in box 6 can be found immediately after determining that the renban line spanning boxes 6 and 9 are 12345, by just following the purple renban line to box 7. It was loads and loads of fun hopping around and around the grid. I don't know that I solved it the intended way, but I really enjoyed that there were lots of options.
After a couple of errors, I solved it. At the start I was wondering is r5c5 would be 5, but, took the long way. What would hasten Simon's solve was noting the two 789's in box 4, and the two 123's in box 6, must include a 9 and 1 respectively, else both 7 and 8 or both 2 and 3, cannot be placed horizontal 9-cell renban. Then, using similar logic the 78 must be row 4 and the 23 in row 6, else you cannot place both numbers on the horizontal renban. That places the 1 [r5c9] and 9 [r5c1] in row 5.
I always get excited to see videos under 40 minutes because it usually means I can take a crack at it! I was able to get this one with a tiny bit of help from Simon. The symmetry of this puzzle with the 10-sums is absolutely beautiful!
I love this puzzle! I sort of solved it backwards from the way Simon solved it; I placed a red and a blue digit in column 5 of the center box fairly early, found 1 and 9 as the other half of those pairs, and proceeded to Sudoku with blue/orange/red/purple in place of the 2/3 and 7/8 pairs. I didn't manage to disambiguate them until near the very end of the puzzle, when I finally placed digits in the shaded Even cells in boxes 2 and 8.
Great puzzle. Simon said a few times it has "a lot of" symmetry and the solve was "a bit like" using Gurth's symmetrical placement. But those qualifiers are slightly misleading since the givens are, in fact, perfectly symmetrical.
Even after a lot of thinking, I don't get my head around the though process of 23:06 with the result that C1R5 and C7R4 must contain the same digit (either 7, 8 or 9). What I am thinking is that C7R4 is only of of two possibilities to mirror the digit from C1R5. The second option would be C9R4, meaning that the digit could then only be 9. I couldn't find any way to rule out one of those two ways in order to continue the puzzle. Ever since, I am stuck at 23:06, only with 2 unrelated additional digits placed.
The purple renban line contains all the digits 1 to 9, and c1 contains all the digits 1 to 9, so Simon's working out where the digit that's in r5c1 appears on that line. It can't appear anywhere else in c1, box4 or r5 just by sudoku, and he knows that the digit in r5c1 is a 7 8 or 9. It can't go in r4c8 or r3c9 because they already contain digits in the range 1 to 4, and r5c1 isn't in that range. So whatever digit goes in that cell also has to go in r4c7, there's nowhere else it can go.
@@DanFre40 Thanks a lot, I focussed on row 4 and actually oversaw how the ranban only left 1 sport for that number. But well, I think I found another path out of my dilemma as well. I wrote it down before I saw your comment, so it makes no difference for me if I poste or waste it ;) First of all: C8R4 must be 4, because it sees all three cells from the 123-triple in box 3 (2 cells in the cullomn, 1 cell by renban. By the same (mirrored) logic, the 6 is forced into C2R6. This solves the digits 4 (C6R6) and 6(C4R4) in the middle cage. Now, 4(C3R5) and 6(C7R5) are naked singles by sudoku in boxes 4 and 6. Then, I thought about the number that would left behind from the blue 123-cells. When the blue cells are filled, there are only very few places for that leftover digit (which can be 1, 2 or 3). Only possible locations are C8R7, C7R6, C9R3. C7R4 is ruled out by renban from C9R3. To be honest, I can’t remember what my next step was then and it is too late for me to redo the whole sudoku ;)
You are right, Simon got a bit lucky here. But if you follow the line with 9 in C1R5 and C9R4 for a while you will find that the central box no longer can contain any 2,3,7,8
The digit in r5c1 must appear somewhere on the long horizontal renban line, but it sees the first six cells, so it can’t go there; it must go somewhere on the last three digits. In fact, you can place a 9 in that cell as early as 15:51, since the last three digits on the line can’t be 7 or 8. (And a 1 in r5c9 even earlier for the same reason)
25:59 ... but I must admit to taking a shortcut ... . . . I saw straight-away that the puzzle had 180-degree symmetry, so I 'knew' that 5 would go in the center cell. I tried to solve this without using such knowledge, but after getting stuck for a spell, I said 'to heck with it' and went ahead with that, using symmetry from then on out. Nice puzzle!
I'm at 9:49 and I'm pretty sure the 5 goes smack dab right in the center of this puzzle.. lol will update if I'm right or wrong lol 😆😂 31:09 lol I was right
took me ages to twig the entry, and then it went quite fast. I worked both big renbans at once to place the 5 in the centre and then pretty much as simon, back and forth through symmetry. Lots of fun..
Was tough for me. 100 minutes or so. But very fun to figure out. I felt like I used some advanced sudoku stuff I learned on this channel while solving it, which was an extra treat.
I'm curious if Simon is explicitly not immediately placing the symmetrical digits and instead going through the same logic twice for the sake of making the video understandable, or if he would do that regardless of if he was recording or not. I always take the opportunity to use GSP whenever it presents itself, so once I've confirmed that all the given information is exactly symmetrical, I'm confident that I can place digits based on symmetry without reconfirming the logic each time.
It's the same reasoning he doesn't use uniqueness in his solves. Part of the solve is proving that it is symmetrical, and you can't do that by assuming symmetry in the first place. But it's not cheating or anything, in a competition or just for fun, nothing wrong with using it if you spot it.
It would be entirely possible to have a puzzle that had an *almost* perfectly symmetrical setup except for one sneaky digit, so that at first glance it would _look_ like it was going to give a symmetrical grid but that one digit would actually send it off course. Better to prove each conclusion a second time from first principles than risk having missed that one wrinkle in the symmetry! Also, it is a form of uniqueness deduction - using the symmetrical placement _assumes_ that there is a single unique solution, whereas the aim of these solves is to _prove_ that there is a single unique solution.
There are two aspects to the symmetry - it’s fine to replicate a deduction on the other side of the grid using symmetry, because you know the logic will work exactly the same way, but NOT fine to place the central 5 for example, which does assume uniqueness.
@@stevieinselby I get what you're saying, but even if the puzzle had multiple solutions, the fact that the given information is symmetrical means that the digits you could determine to be unique still have to obey symmetry, because the logic you used to find those digits stemmed from one half of symmetrical given information. And the undeterminable cells would still have to have symmetry in their placement and possible digits. It is true though that a symmetrical puzzle without a unique solution could have solutions that aren't symmetrical, but the cells that break symmetry in those solutions could only be the symmetrically placed cells that had multiple candidates.
@@stiffmidget Right, but you can prove symmetry for all unique digits at the start of a puzzle if that puzzle has symmetrical given information. If the puzzle is not symmetrical, the information that breaks the symmetry must be given at the very start.
I was one deduction away from completing this fully by myself, so frustrating! It was a great puzzle, I just didn't spot the coloured pair logic Simon did in box 4 and 6.
I'm a believer that Simon's voice is therapeutic ❤️ Love the sudoku part more than anything else, but I'm guilty of watching his videos and it may sometimes be a lullaby for me (maybe because the mind is tired solving sudoku too)
Great debut puzzle, great solve, although the poor four at the top of column 7 was apparently invisible to Simon. He pencil marked a 4 in the column twice in (7,7), even when the column had 8 digits already placed.
Once you suspect symmetry like that, step back and look at the clues. Every clue rotates onto itself, where the numbers in the clues add to 10. Therefore the final grid *must* obey that rule. (You can do the same thing with killer cages, but the cages that map to one another need to map to 10 times the number of cells in the cage.)
Given that all the hints were rotationally (and 10-x) symmetrical (and the Renban and even-rules fit to it), if this has a unique solution, the solution also needs to have this same symmetry. I guess that's an extension of Gurth's theorem (www.sudokuwiki.org/Gurths_Theorem) to include other rules. I guess not using it directly to solve the puzzle faster (only to remember tricks done earlier) is justified, just as we don't assume there is a unique solution from the start.
That was a really nice debut, with some clever logic. Once I realize a puzzle is symmetrical like this, I'm slightly disappointed. Not because it's not beautiful, but because I only need to solve half a puzzle, and the fun will be over quicker. When a puzzle is this nicely constructed, I want the fun to last.
I had just joined patreon, and I've only tried one, and omg do I have a lot to learn. I mean, I knew that it wasn't going to be easy, but I at least thought I could get through part of it, I mean damn. But so happy I joined and love watching.
39:34. What a great puzzle. The logic made sense, but never really seemed that straightforward. For me, this is how the logic broke down. 1) The renbans around the quad circles forced certain digits (e.g., 23 forcing 45 and a 1 or 6, 45 being potentially from 1 to 8). 2) The 5 was very limited across the vertical-9 renban forcing the 5 in the middle column in the middle box. 3) This limited the 4 and 6 across the same vertical-9 renban which forced the 45 renban to be from 1 to 5 and and the 56 renban to be from 5 to 9. 4) The puzzle was completely symmetrical and the digits could be swapped for its counterpart (1 for 9, 2 for 8, etc.) forcing the 5 to be in the middle. 5) The even squares in box 1 and 9 could not be 8 or 2 respectively because then that would force them on the renban into box 2 and 8 but then into column 3 and 7 which was not possible. 6) r5c1 and r5c9 which had to be 789 or 123 respectively saw every part of the horizontal-9 renban line except for in box 23 and 78, and 78 and 23 were not allowed on those renban spaces. Each part was distinctly different and never really felt straightforward from the previous step, but they all came together to make it an approachable if still pretty difficult solve. I love how the renbans were used pretty consistently, but in different ways to limit what could be in the squares. Thanks for the interesting puzzle!
The logic that you used was so much more elegant than how The Werefrog did it, and it went much faster, too. 'Tis always amazing how quickly you can see these things.
Wow, this was really hard for me to solve (without cheating by having a strong hunch about the central number and just using symmetry), but it was so satisfying how each stage fed into the next and the interactions that propagated around. Very cool puzzle, now to watch the video and watch a master find the path :)
At 23:04, Simon concludes that r5c1 = r4c7. But why couldn't r5c1 be a 9 and hence go in r4c9? EDIT: Completed the puzzle. You can use the same logic with the blue 123's on the purple renban line to make r6c3 blue.
Wow, I totally missed that color logic with the sixes early on. I had to break this puzzle using set notation with the purple renban and Row 5 to place the 1 and 9 in Row 5.
18:13 for me. I wonder whether at this point it is fine to place a 5 in the middle of the grid as soon as you open the puzzle when it comes to these symmetrical ones or that would still be considered “cheating”. I didn’t use that trick in my solve anyways, but it would have probably helped at some point.
it's the same as using uniqueness: if all clues are gurth symmetric (with a+b=10) then there is a gurth symmetric solution und (using uniqueness) this is the only solution. so the central square is then 5.
46:46, but I was stuck at the @11:00 spot in the video and didn't see how to rule 6 out of the rendan line. Pretty easy after that. I was impressed that it stayed symmetrical and yet was solvable until the very end. I guess the slightly different shapes of the two 9-digit lines is enough to disambiguate.
3h 20m. Oof, another long one. Every step I made I kept expecting it to open up, but it just kept stubbornly holding out. I probably zigged when I should've zagged somewhere, or maybe I would've found an easier path more like Simon's. In any case, I could tell right away that it was symmetrical, but I wasn't going to allow myself to rely on it (except to look for counterpart logic), and in fact, I was wondering all the way through how it would resolve itself. Most symmetrical puzzles seem to need some kind of symmetry-breaker before the end, or else you'd get a deadly pattern. I had to keep going just to find out how it would fall into place. So, overall, a very tough one for me, but it was more a case of continuing to plug away at it than requiring any really tricky logic.
I totally lost my cool with this one, I just wasn't able to solve it. Nice to see the clear logic behind it. Now I'm going to do some easier sudokus and hopefully regain a stable state of mind.
Once you have the blue 1-2-3, you know one of the blue is 1 because if it were 2-3 there would be nowhere to place 2 and 3 on the magenta line. This is somewhat analogous to what Simon did later with the red 7-8-9.
Approachable means that solving it doesn't require doing complex logic in your head or knowing lots of solving techniques. So approachable but not easy means that the puzzle isn't complicated, but it will take longer than a few minutes to solve.
i’m surprised simon didn’t use the symmetrical 10 clue more during the solve. after he pointed it out it was all i could focus on. either way the puzzle was beautiful and he did a great job :)
At 28:00 the grey cell could be in r6c1 instead of r6c3 if it was a 1 (having the option to be 1,2 or3 ). You could argue symmetry but Simon is not using symmetry to solve the puzzle. Or am I missing something ?
r6c1 isn't on the purple renban line. He's looking for where the 'grey' digit in r5c9 (1, 2 or 3) goes on the renban line. It can only go in r6c3 on the line. (I don't know why you wouldn't make use of the symmetry. It's a perfectly symmetrical puzzle. Any deduction you make must be applicable symmetrically. Why waste effort thinking through the exact same logic twice all the time? Just enter the symmetrical digits as you find their counterparts. 🙂)
In 22:57 how did he know the value of r5c1 wasn't a 9 and repeat in r4c9 instead of r4c7? Am I wrong to think he overlooked that possibility and was lucky? Anyway, the contents of some of the renban lines could have been determined earlier by noticing the the 2:s in box 7 and 8:s in box 3 were along the lines.
Im, sorry, I got it ! but Simon passed over this point rather quickly. If R4C9 it the same 9 as in R5C1, there would be no room for the 9 on the renban line. I just forgot that premice in the reasoning.
If you take this sudoku, rotate it 180 degrees, put it on top of itself and add the numbers that are on top of each other, the grid will be all 10s. Which is fitting because this puzzle is a 10/10!
Would it be cheating to place the digit on row 5 column 5 as soon as you notice the board is mirrored? I was 100% sure it'd be a 5 since that's the 'leftover' of adding all numbers on the page but I tried to ignore it until the end
I made the same conjecture as soon as I narrowed 5 to c5 in box 5 but since I couldn't immediately copy/paste the logic I also waited. Maybe there is a rotational argument to place it but not that I could see.
@@uberchops what held me back was that there was no rule about opposite digits summing up to 10, so even though all of them _did_ sum to 10, I could never assume the pattern wouldn't eventually break
Actually since the givens are all symetric under rotation over 180 degrees AND subtracting from 10, you know that the whole puzzle will have that symmetry. I think that if you use the fact that there is a unique solution you can basically solve half of the grid and fill the rest in using the symmetry. The 5 in the centre you get for free. The catch is here that i heard Simon say in a recent video that he doesn't want to use the fact that there is a unique solution...
As half-a-puzzle, it's still quite a good one. But I agree, the symmetry just means you end up doing everything twice to complete the grid. They're less interesting to solve than non-symmetrical puzzles.
Haha! I see what you did there Simon. I feel Simon was making fun of my earlier comments on the problem of colouring known digits by making 9 yellow all of a sudden and then commenting on it by getting confused by the red colouring.
Innocuous here! So glad you enjoyed the puzzle :) Thanks for featuring it!
It's a thing of beauty! Very nicely done.
Excellent work, very satisfying logic and solve.
That was good fun! Not overly tough but with lovely logic.
Great job. Loved the puzzle.
Pretty good puzzle, had some very interesting logic there.
Most days this doesn't even occur to me, which just goes to show how expertly you do it, but it's pretty rare to see RUclips videos with no edits/cuts, especially on something such as this with an intro, a complete as-live solve, and then an outro. (Unicorn-related emergencies don't count as edits.) I imagine that's partly why so many people find this channel relaxing, because you're not hit with a jump cut every 3 seconds, it's like a long soak in a warm bath, whereas so many videos are like 100 buckets of cold water thrown in your face. I really appreciate that.
I absolutely agree!
And it’s Simon’s sense of wonder and discovery that makes this the best let’s play on RUclips!
@@GunganWorks yes! It’s the human element. Especially over the course of this pandemic, humanity has seemed scarce, and yet he has found his own way to provide it online.
@@th.nd.r I fully endorse your endorsement! Simon and Mark are friends you can hang out with. The quirky humour and the profundity of the logic are truly addictive. This channel has become a constant companion during lockdown - which I am sure was not a picnic for most. They should be recognised as one of the very good things to come out of a miserable year. I would welcome a knighthood for them. Seriously.
True. Some cut after every sentence. Makes me restless and puts me on edge… especially once I pay attention.
If anyone else wants another channel that has a similar style of no cuts and one take filming. I recommend GothamChess, he's an amazing RUclipsr who posts almost daily and does all his videos in one take.
He also does chess videos, which is another game that requires logical thinking and stimulates my brain in much the same way ctc does
I do recommend checking him out
"some of you might mumble that I have no strengths"
My guy, you're solving some of the most insane sudokus and puzzles, all the while explaining your logic in an understandable way, while some of us (including me) are still processing the rules
Amen!
Ong
The logic just goes round and round the grid. Like some sort of flywheel or something.
Yes, entirely grid is proportionally with sums up to 10 in every proportional cell except the 5 in the middle!
i've been trying all the puzzles featured on this channel for the past couple weeks (well only the ones with sub-45 minute solve times for simon), and today's was the first i finished without consulting the video for hints!
I'm impressed! Personally, I don't get anywhere close on my own. The best I do is occasionally to shout at the screen when I think I've seen something they've missed ... and half the time I'm wrong 😳😂
Have you tried creating a puzzle of your own yet? I'd recommend watching Clover's video about how she sets puzzles if you haven't.
ruclips.net/video/IE1N6B6SHQA/видео.html
Enjoy ... 👍
you'redoing great, keep going!!! :)
I don't know who Prized Charlie is, but he must be very good at Sudoku.
As part of my ongoing series of "variant solves" which I do totally on purpose and definitely not because I'm an idiot (cough), it turns out if you treat squares as containing only _odd_ digits, you get completely and utterly stuck.
🤣 While I didn't do that on this puzzle, I've made similar reversals before. Oddly, they never seem helpful.
21:13 "Prize Charlie" is the new "Chocolate Teapot". For those of you who aren't obsessed with cryptic crossword language word-play, "Prize Charlie" is a reverse portmanteau for the wartime British slur "Pusillanimous Charles Hunt". You take the the first letter of Charles, 'C', and you add it to the final 3 letters of Hunt, 'unt', then you gussy it up for a family-friendly broadcast, and you get "Prize Charlie".
Wow no wonder urban dictionary didn’t have this definition
Not clear what you meant. I know nothing about cryptic crosswords and English is not my native language. You clearly explained what "Charles Hunt" meant in that wartime slur (en.wikipedia.org/wiki/Portmanteau).
An attenuated version of the slur would be something like "Brave C. Hunt" or "Brave Charlie" (where "C. Hunt" still means "weak and coward"). However, "prize" is a verb, isn't it? So, how can someone be described as a "Prize C. Hunt" or "Prize Charlie" (21:13), and how can "Prize" be the reverse of "Pusillanimous"?
If someone can translate this to English it would be great.
@@Paolo_De_Leva
Cryptic crosswords are very confusing, even for native speakers, so don't feel bad, I don't get this either.
Cryptics use certain rules and leading phrases and gotcha's all in a totally new kind word logic game that I've never seen before. Look up cryptics on the CTC videos list, and watch Simon's walkthrough/solve of a cryptic. It's astounding the logic and stuff he comes up with. You can watch Mark's cryptic solves as well, he blazes thru them at lightning speed.
I really appreciate the explanation, I’ve wondered for months where Prize Charlie could come from… another impossible to guess british long-tailed joke!
Dear Simon after only being an amazed watcher for a few weeks now I finally decided to try this puzzle before watching your video and although it took me much longer to solve than it did take you I am proud to say I was able to do it and I wanted to thank you both for introducing people to the wonderful world of advanced sudoku!
I loved the symmetry, but I loved how the puzzle solves from the outer edges into the center. Very appropriate for a 'Flywheel' :)
This puzzle is a great example of GSP. Everything’s so symmetric, even including the numbers, that any time a 1 is placed, a 9 can be placed across the grid by the same logic. Same goes for 2&8, 3&7, 4&6. Only 5 is unaffected by another digit, although there are certain locations that 5 can be immediately ruled out of due to this.
Once you realise the puzzle is symmetric like this, is it cheating to fill in all the opposite digits straight away? or should you carry on using logic to deduce them like Simon did? I sort of feel that, for example, once you know there's an 8 in r7c1, immediately pairing it with a 2 in r3c9 would be taking a very sneaky shortcut.
@@DanFre40 may feel sneaky but it’s totally valid.
@@afrayedknot81 I've just been reading some of the other comments and seen a lot of other people asking the same question - only to be told that you can't guarantee the entire puzzle is symmetrical! I wouldn't put it past a setter to sneakily swap a couple of digits at the end of the solve path to trip up everyone who thought they could get away with only solving half the clues!
@@DanFre40 That’s actually impossible (otherwise the puzzle has multiple solutions). There’s nothing in the rules that could possibly break the symmetry.
@@DanFre40 I pulled up an earlier version of the puzzle I thought had a non-symmetrical solution, and realized it was a broken puzzle, so I believe I was wrong about that. (It also used some short two-cell thermos instead of evens squares, so it’s possible there is a version that could work non-symmetrically, but thermos don’t exactly follow the 1/9 2/8 3/7 4/6 symmetry rules)
I really enjoyed this puzzle. It felt like after the deduction at around 10:30 and onwards, there were many places to pick at it and get results, so after that first challenge it was very fun. For example the 1 in box 6 can be found immediately after determining that the renban line spanning boxes 6 and 9 are 12345, by just following the purple renban line to box 7.
It was loads and loads of fun hopping around and around the grid. I don't know that I solved it the intended way, but I really enjoyed that there were lots of options.
After a couple of errors, I solved it. At the start I was wondering is r5c5 would be 5, but, took the long way. What would hasten Simon's solve was noting the two 789's in box 4, and the two 123's in box 6, must include a 9 and 1 respectively, else both 7 and 8 or both 2 and 3, cannot be placed horizontal 9-cell renban. Then, using similar logic the 78 must be row 4 and the 23 in row 6, else you cannot place both numbers on the horizontal renban. That places the 1 [r5c9] and 9 [r5c1] in row 5.
I always get excited to see videos under 40 minutes because it usually means I can take a crack at it! I was able to get this one with a tiny bit of help from Simon. The symmetry of this puzzle with the 10-sums is absolutely beautiful!
The debut is really beautiful. I couldn't come up with it or solve it. The only thing I can do is gratefully appreciate it's beauty...
I love this puzzle! I sort of solved it backwards from the way Simon solved it; I placed a red and a blue digit in column 5 of the center box fairly early, found 1 and 9 as the other half of those pairs, and proceeded to Sudoku with blue/orange/red/purple in place of the 2/3 and 7/8 pairs. I didn't manage to disambiguate them until near the very end of the puzzle, when I finally placed digits in the shaded Even cells in boxes 2 and 8.
I like the rotational symmetry type sudoku puzzles, it's like figuring out how magic is done
Great puzzle. Simon said a few times it has "a lot of" symmetry and the solve was "a bit like" using Gurth's symmetrical placement. But those qualifiers are slightly misleading since the givens are, in fact, perfectly symmetrical.
Such a beautiful puzzle. Going to check out all of Innocuous' puzzles from here on out!
This is my new favorite puzzle. It makes my OCD feel all warm and fuzzy.
This puzzle is absolutely symmetric - by adding everything to 10! Amazing how one can construct one like this!
Even after a lot of thinking, I don't get my head around the though process of 23:06 with the result that C1R5 and C7R4 must contain the same digit (either 7, 8 or 9). What I am thinking is that C7R4 is only of of two possibilities to mirror the digit from C1R5. The second option would be C9R4, meaning that the digit could then only be 9. I couldn't find any way to rule out one of those two ways in order to continue the puzzle.
Ever since, I am stuck at 23:06, only with 2 unrelated additional digits placed.
The purple renban line contains all the digits 1 to 9, and c1 contains all the digits 1 to 9, so Simon's working out where the digit that's in r5c1 appears on that line. It can't appear anywhere else in c1, box4 or r5 just by sudoku, and he knows that the digit in r5c1 is a 7 8 or 9. It can't go in r4c8 or r3c9 because they already contain digits in the range 1 to 4, and r5c1 isn't in that range. So whatever digit goes in that cell also has to go in r4c7, there's nowhere else it can go.
@@DanFre40 Thanks a lot, I focussed on row 4 and actually oversaw how the ranban only left 1 sport for that number.
But well, I think I found another path out of my dilemma as well. I wrote it down before I saw your comment, so it makes no difference for me if I poste or waste it ;)
First of all: C8R4 must be 4, because it sees all three cells from the 123-triple in box 3 (2 cells in the cullomn, 1 cell by renban. By the same (mirrored) logic, the 6 is forced into C2R6.
This solves the digits 4 (C6R6) and 6(C4R4) in the middle cage.
Now, 4(C3R5) and 6(C7R5) are naked singles by sudoku in boxes 4 and 6.
Then, I thought about the number that would left behind from the blue 123-cells. When the blue cells are filled, there are only very few places for that leftover digit (which can be 1, 2 or 3). Only possible locations are C8R7, C7R6, C9R3. C7R4 is ruled out by renban from C9R3.
To be honest, I can’t remember what my next step was then and it is too late for me to redo the whole sudoku ;)
You are right, Simon got a bit lucky here. But if you follow the line with 9 in C1R5 and C9R4 for a while you will find that the central box no longer can contain any 2,3,7,8
The digit in r5c1 must appear somewhere on the long horizontal renban line, but it sees the first six cells, so it can’t go there; it must go somewhere on the last three digits. In fact, you can place a 9 in that cell as early as 15:51, since the last three digits on the line can’t be 7 or 8. (And a 1 in r5c9 even earlier for the same reason)
25:59 ... but I must admit to taking a shortcut ...
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I saw straight-away that the puzzle had 180-degree symmetry, so I 'knew' that 5 would go in the center cell. I tried to solve this without using such knowledge, but after getting stuck for a spell, I said 'to heck with it' and went ahead with that, using symmetry from then on out.
Nice puzzle!
I haven't watched a video for a few months now and I almost forgot how relaxing it is watching Simon do this
Beautiful symmetry, and the rules complement each other very nicely. A fantastic debut indeed!
Beautiful puzzle! I muddled my way through, and now look forward to watching an elegant solve...
This was a really fun puzzle. For me it had great pacing where I was figuring something new out every minute or so and finished in 41 minutes.
I'm at 9:49 and I'm pretty sure the 5 goes smack dab right in the center of this puzzle.. lol will update if I'm right or wrong lol 😆😂
31:09 lol I was right
I love the rotational symmetry puzzles: they have such a nice flow to them
Simon I absolutely love watching the echos pass across your brain while doing these symmetrical puzzles
Wonderfully, Intricate and clever puzzle with very helpful symmetry to speed the solve along, thanks.
the symmetry in this puzzle sparks joy
I haven't even watched the video yet, but that blank board is *beautiful*.
I'm really envious of your reasoning speed! It took me way longer to make these observations.
I really enjoyed watching this. Incredibly elegant and beautiful symmetry
took me ages to twig the entry, and then it went quite fast. I worked both big renbans at once to place the 5 in the centre and then pretty much as simon, back and forth through symmetry. Lots of fun..
1:07:20 One dinosaur please xD It was a great puzzle, I really liked its symmetry
Simon-ism of the day - "Prize Charlie" coming to dinner! 21:13
But can you smell that Charlie across the room like Benny Hill?
just when I thought I was up to speed on my british he says that. lol
Was tough for me. 100 minutes or so. But very fun to figure out. I felt like I used some advanced sudoku stuff I learned on this channel while solving it, which was an extra treat.
I'm curious if Simon is explicitly not immediately placing the symmetrical digits and instead going through the same logic twice for the sake of making the video understandable, or if he would do that regardless of if he was recording or not. I always take the opportunity to use GSP whenever it presents itself, so once I've confirmed that all the given information is exactly symmetrical, I'm confident that I can place digits based on symmetry without reconfirming the logic each time.
It's the same reasoning he doesn't use uniqueness in his solves. Part of the solve is proving that it is symmetrical, and you can't do that by assuming symmetry in the first place. But it's not cheating or anything, in a competition or just for fun, nothing wrong with using it if you spot it.
It would be entirely possible to have a puzzle that had an *almost* perfectly symmetrical setup except for one sneaky digit, so that at first glance it would _look_ like it was going to give a symmetrical grid but that one digit would actually send it off course. Better to prove each conclusion a second time from first principles than risk having missed that one wrinkle in the symmetry! Also, it is a form of uniqueness deduction - using the symmetrical placement _assumes_ that there is a single unique solution, whereas the aim of these solves is to _prove_ that there is a single unique solution.
There are two aspects to the symmetry - it’s fine to replicate a deduction on the other side of the grid using symmetry, because you know the logic will work exactly the same way, but NOT fine to place the central 5 for example, which does assume uniqueness.
@@stevieinselby I get what you're saying, but even if the puzzle had multiple solutions, the fact that the given information is symmetrical means that the digits you could determine to be unique still have to obey symmetry, because the logic you used to find those digits stemmed from one half of symmetrical given information. And the undeterminable cells would still have to have symmetry in their placement and possible digits. It is true though that a symmetrical puzzle without a unique solution could have solutions that aren't symmetrical, but the cells that break symmetry in those solutions could only be the symmetrically placed cells that had multiple candidates.
@@stiffmidget Right, but you can prove symmetry for all unique digits at the start of a puzzle if that puzzle has symmetrical given information. If the puzzle is not symmetrical, the information that breaks the symmetry must be given at the very start.
I was one deduction away from completing this fully by myself, so frustrating! It was a great puzzle, I just didn't spot the coloured pair logic Simon did in box 4 and 6.
That puzzle was cool!! I only wish that you colored the numbers just to see the grid colored symmetrically.
I don't even like sudokus, but for some strange reason I really enjoy your videos
I'm a believer that Simon's voice is therapeutic ❤️
Love the sudoku part more than anything else, but I'm guilty of watching his videos and it may sometimes be a lullaby for me (maybe because the mind is tired solving sudoku too)
I've managed to drift off more than once while watching Simon solve a sudoku.
I completed this puzzle using absolutely different logic :D It's an amazing puzzle
Great debut puzzle, great solve, although the poor four at the top of column 7 was apparently invisible to Simon. He pencil marked a 4 in the column twice in (7,7), even when the column had 8 digits already placed.
Once you suspect symmetry like that, step back and look at the clues. Every clue rotates onto itself, where the numbers in the clues add to 10. Therefore the final grid *must* obey that rule.
(You can do the same thing with killer cages, but the cages that map to one another need to map to 10 times the number of cells in the cage.)
I don’t get the meaning of your last remark. Ten times what?
What a debut. Pretty puzzle.
Oh, that's a pretty puzzle. The rotational parallels are very clever. A few seconds over 40m, and I'm pleased with that.
Given that all the hints were rotationally (and 10-x) symmetrical (and the Renban and even-rules fit to it), if this has a unique solution, the solution also needs to have this same symmetry. I guess that's an extension of Gurth's theorem (www.sudokuwiki.org/Gurths_Theorem) to include other rules.
I guess not using it directly to solve the puzzle faster (only to remember tricks done earlier) is justified, just as we don't assume there is a unique solution from the start.
Ah, my evening dose of happiness and bright colours. This one was very... rotational.
What a lovely puzzle! And the solve was so entertaining!
That was a really nice debut, with some clever logic. Once I realize a puzzle is symmetrical like this, I'm slightly disappointed. Not because it's not beautiful, but because I only need to solve half a puzzle, and the fun will be over quicker. When a puzzle is this nicely constructed, I want the fun to last.
I had just joined patreon, and I've only tried one, and omg do I have a lot to learn. I mean, I knew that it wasn't going to be easy, but I at least thought I could get through part of it, I mean damn. But so happy I joined and love watching.
I just spent 15 minutes treating the renban lines as palindromes instead and actually got pretty far before realizing my mistake.
YES!!!! I did the same thing, except it was after 45 minutes and I had 95% of the grid either filled in or pencil marked. lol
If they are palindromes the middle box would be broken.
39:34. What a great puzzle. The logic made sense, but never really seemed that straightforward.
For me, this is how the logic broke down.
1) The renbans around the quad circles forced certain digits (e.g., 23 forcing 45 and a 1 or 6, 45 being potentially from 1 to 8).
2) The 5 was very limited across the vertical-9 renban forcing the 5 in the middle column in the middle box.
3) This limited the 4 and 6 across the same vertical-9 renban which forced the 45 renban to be from 1 to 5 and and the 56 renban to be from 5 to 9.
4) The puzzle was completely symmetrical and the digits could be swapped for its counterpart (1 for 9, 2 for 8, etc.) forcing the 5 to be in the middle.
5) The even squares in box 1 and 9 could not be 8 or 2 respectively because then that would force them on the renban into box 2 and 8 but then into column 3 and 7 which was not possible.
6) r5c1 and r5c9 which had to be 789 or 123 respectively saw every part of the horizontal-9 renban line except for in box 23 and 78, and 78 and 23 were not allowed on those renban spaces.
Each part was distinctly different and never really felt straightforward from the previous step, but they all came together to make it an approachable if still pretty difficult solve.
I love how the renbans were used pretty consistently, but in different ways to limit what could be in the squares.
Thanks for the interesting puzzle!
Completed in 22m24s.
How clever was that? Not brutally hard, but still required very exact logical conclusions at every step.
The next suduko app would be fun if it is quadrabels clues!
108:39. been gone a few months works stuff, fun puzzle.
The logic that you used was so much more elegant than how The Werefrog did it, and it went much faster, too. 'Tis always amazing how quickly you can see these things.
Wow, this was really hard for me to solve (without cheating by having a strong hunch about the central number and just using symmetry), but it was so satisfying how each stage fed into the next and the interactions that propagated around. Very cool puzzle, now to watch the video and watch a master find the path :)
At 23:04, Simon concludes that r5c1 = r4c7. But why couldn't r5c1 be a 9 and hence go in r4c9?
EDIT: Completed the puzzle. You can use the same logic with the blue 123's on the purple renban line to make r6c3 blue.
yes - i thought the same momentarily, but he is looking up the renban line only, not the row, so r4c9 is not on the renban line.
@@marcosharlequin Ah of course! Thank you :)
Wow, I totally missed that color logic with the sixes early on. I had to break this puzzle using set notation with the purple renban and Row 5 to place the 1 and 9 in Row 5.
18:13 for me. I wonder whether at this point it is fine to place a 5 in the middle of the grid as soon as you open the puzzle when it comes to these symmetrical ones or that would still be considered “cheating”. I didn’t use that trick in my solve anyways, but it would have probably helped at some point.
it's the same as using uniqueness: if all clues are gurth symmetric (with a+b=10) then there is a gurth symmetric solution und (using uniqueness) this is the only solution. so the central square is then 5.
46:46, but I was stuck at the @11:00 spot in the video and didn't see how to rule 6 out of the rendan line. Pretty easy after that. I was impressed that it stayed symmetrical and yet was solvable until the very end. I guess the slightly different shapes of the two 9-digit lines is enough to disambiguate.
3h 20m. Oof, another long one. Every step I made I kept expecting it to open up, but it just kept stubbornly holding out. I probably zigged when I should've zagged somewhere, or maybe I would've found an easier path more like Simon's.
In any case, I could tell right away that it was symmetrical, but I wasn't going to allow myself to rely on it (except to look for counterpart logic), and in fact, I was wondering all the way through how it would resolve itself. Most symmetrical puzzles seem to need some kind of symmetry-breaker before the end, or else you'd get a deadly pattern. I had to keep going just to find out how it would fall into place.
So, overall, a very tough one for me, but it was more a case of continuing to plug away at it than requiring any really tricky logic.
I totally lost my cool with this one, I just wasn't able to solve it. Nice to see the clear logic behind it. Now I'm going to do some easier sudokus and hopefully regain a stable state of mind.
It took me some time to realise the implications of r5c1 and r5c9 on the renban line going horizontally.
Beautiful puzzle
Once you have the blue 1-2-3, you know one of the blue is 1 because if it were 2-3 there would be nowhere to place 2 and 3 on the magenta line. This is somewhat analogous to what Simon did later with the red 7-8-9.
Lovely debut puzzle
I have a question when Simon says a puzzle is approachable but not easy what does he mean by that?
Approachable means that solving it doesn't require doing complex logic in your head or knowing lots of solving techniques. So approachable but not easy means that the puzzle isn't complicated, but it will take longer than a few minutes to solve.
i’m surprised simon didn’t use the symmetrical 10 clue more during the solve. after he pointed it out it was all i could focus on. either way the puzzle was beautiful and he did a great job :)
Because it *might* be slightly off and then you would be screwed, its best not to assume things and to logic your way through instead :)
At 28:00 the grey cell could be in r6c1 instead of r6c3 if it was a 1 (having the option to be 1,2 or3 ). You could argue symmetry but Simon is not using symmetry to solve the puzzle. Or am I missing something ?
r6c1 isn't on the purple renban line. He's looking for where the 'grey' digit in r5c9 (1, 2 or 3) goes on the renban line. It can only go in r6c3 on the line.
(I don't know why you wouldn't make use of the symmetry. It's a perfectly symmetrical puzzle. Any deduction you make must be applicable symmetrically. Why waste effort thinking through the exact same logic twice all the time? Just enter the symmetrical digits as you find their counterparts. 🙂)
You didn't use purple. Who are you and what did you do with Simon? :)
With everything adding to 10, I could see the central 5 a mile away.
how do you color in a field with two colors,. with the webapp?
Use the “ multiclour mode on” in the settings.
symmetry of 10's
Lovely puzzle, even if I did need Simon's help a couple of times.
Simon: Look at the symmetry!
Me: (thinking) Is the central square a 5?
Very nice and satisafaying puzzle! Loved it.
It has to be … if you are prepared to make the assumption that there is a unique solution.
We need Maverick to be a guest on a podcast episode... #DoesHeLikeSudoku?
In 22:57 how did he know the value of r5c1 wasn't a 9 and repeat in r4c9 instead of r4c7? Am I wrong to think he overlooked that possibility and was lucky? Anyway, the contents of some of the renban lines could have been determined earlier by noticing the the 2:s in box 7 and 8:s in box 3 were along the lines.
Oh I see it now, r4c9 is not along that renban line
Yeah, I made the same mistake. Thanks for explaining the issue.
Amazing
Me at minute 28:00 :
This number is 1-9, 2-8, 3-7, 4-6 pair by board symmetry.
Very entertaining!
Im, sorry, I got it ! but Simon passed over this point rather quickly. If R4C9 it the same 9 as in R5C1, there would be no room for the 9 on the renban line. I just forgot that premice in the reasoning.
If you take this sudoku, rotate it 180 degrees, put it on top of itself and add the numbers that are on top of each other, the grid will be all 10s. Which is fitting because this puzzle is a 10/10!
I feel like I'm missing something really obvious. I got a handful of digits and some pairs but I can't see how to proceed any further.
I think you got lucky around 23:00. From what I see r4c9 could have been a 9, not just r4c7.
r4c9 isn't on the purple renban line, though. He's looking for where the (789) in r1c5 can go on the renban line. It can only go in r4c7 on the line.
At 23:13 why did Simon say that r5c1 (yellow) couldn't map to r4c9 which still could be a 9? Thats the only thing I don't get with this video.
Because he was looking specifically for where it could go on the renban line, and r4c9 isn't on the line.
@@elainedenning okay thanks
Would it be cheating to place the digit on row 5 column 5 as soon as you notice the board is mirrored? I was 100% sure it'd be a 5 since that's the 'leftover' of adding all numbers on the page but I tried to ignore it until the end
I made the same conjecture as soon as I narrowed 5 to c5 in box 5 but since I couldn't immediately copy/paste the logic I also waited. Maybe there is a rotational argument to place it but not that I could see.
@@uberchops what held me back was that there was no rule about opposite digits summing up to 10, so even though all of them _did_ sum to 10, I could never assume the pattern wouldn't eventually break
Actually since the givens are all symetric under rotation over 180 degrees AND subtracting from 10, you know that the whole puzzle will have that symmetry. I think that if you use the fact that there is a unique solution you can basically solve half of the grid and fill the rest in using the symmetry. The 5 in the centre you get for free. The catch is here that i heard Simon say in a recent video that he doesn't want to use the fact that there is a unique solution...
Excellent puzzle :)
Link broken?
Andrew's Law for the win!
I disagree with some of the post-solve comments. These symmetrical puzzles are pretty boring. They reduce the amount of fun and logic by at least 50%.
As half-a-puzzle, it's still quite a good one. But I agree, the symmetry just means you end up doing everything twice to complete the grid. They're less interesting to solve than non-symmetrical puzzles.
Haha! I see what you did there Simon. I feel Simon was making fun of my earlier comments on the problem of colouring known digits by making 9 yellow all of a sudden and then commenting on it by getting confused by the red colouring.
Cool that the central box is also a magic square
It's not a magic square. All the rows and columns don't add to 15.
23:06 I don't see why R4C9 (the 459 triple) cannot be a 9.
not really a fan of symmetrical puzzles, but great solve as always