## The hardest sudokus (new thread)

Everything about Sudoku that doesn't fit in one of the other sections

### Re: The hardest sudokus (new thread)

I tried the three puzzles using YZF_Sudoku. I changed the settings so that MSLS and Junior Exocets are listed before Dynamic Chains.
The first puzzle has a long solution path but after the MSLS, the next hardest step is a Death Blossom :

Code: Select all
`..3....8..5....2.17...........5.8..6.9.12....8....3....6.9....5..4....7.....1.6.2Locked Candidates 1 (Pointing): 7 in b3 => r1c4<>7,r1c5<>7,r1c6<>7Locked Candidates 1 (Pointing): 9 in b5 => r1c5<>9,r2c5<>9,r3c5<>9MSLS:16 Cells r2579c1368, 16 Links 69r2,56r5,12r7,59r9,34c1,78c3,47c6,34c818 Eliminations: r7c7<>1,r4c18,r3c8,r8c1<>3,r346c8,r1c16,r3c6, r4c1<>4,r5c7<>5,r2c45<>6,r46c3<>7,r3c3<>8Locked Pair: in r4c1,r4c3 => r4c2<>12,r6c2<>12,r6c3<>12,r4c2<>12,r4c7<>1,r4c8<>12,Hidden Single: 2 in b6 => r6c8=2Hidden Single: 1 in b6 => r6c7=1Hidden Single: 1 in b9 => r7c8=1Hidden Single: 5 in b6 => r5c8=5Hidden Single: 5 in b4 => r6c3=5Naked Single: r4c8=9Hidden Single: 9 in b5 => r6c5=9Hidden Single: 6 in r6 => r6c4=6Naked Single: r3c8=6Locked Candidates 1 (Pointing): 9 in b9 => r8c1<>9Empty Rectangle : 4 in b5 connected by c1 => r2c5 <> 4Finned X-Wing:4c48\r29 fr13c4 => r2c6<>4Finned Swordfish:4c168\r259 fr7c6 => r9c4<>4Locked Candidates 2 (Claiming): 4 in c4 => r1c5<>4,r3c5<>4AIC Type 2: 3r4c2 = r5c1 - (3=2)r7c1 - (2=1)r4c1 - r8c1 = 1r8c2 => r8c2<>3MSLS:13 Cells r48c457+r123c45,r4c2,r8c9,13 Links 347r4,389r8,2c4,56c5,3478b22 Eliminations: r2c6<>7,r8c2<>8Almost Locked Set XZ-Rule: A=r45c7,r6c9 {3478},B=r7c7,r9c8 {348}, X=8, Z=3 => r8c7<>3 Almost Locked Set XY-Wing: A=r1c24{124}, B=r48c1{125}, C=r8c245679{1235689}, X,Y=1, 5, Z=2 =>  r1c1<>2Almost Locked Set XY-Wing: A=r1c24{124}, B=r579c6{2457}, C=r8c245679{1235689}, X,Y=1, 5, Z=2 =>  r1c6<>2Death Blossom Complex Type 2: Set have degrees of freedom of 0-23478{r7c13567} => r4c2<>43r7c1-(3=12478){r13689c2}3r7c5-(3=45678){r12348c5}3r7c7-(3=47){r4c57}W-Wing: 47 in r5c6,r6c9 connected by 4r4 => r5c79<>7Grouped 2-String Kite: 7 in r5c6,r9c2 connected by r46c2,r5c3 => r9c6 <> 7Death Blossom Complex Type 2: Set have degrees of freedom of 2-3469{r2c18} => r5c9<>46r2c1,9r2c1-(69=12345){r145789c1}3r2c8-(3=479){r136c9}Region Forcing Chain: Each 4 in r1 true in turn will all lead r1c2<>1(4-1)r1c2(4-2)r1c4 = (2-1)r1c24r1c7 - r2c8 = r9c8 - (4=5)r9c6 - r8c56 = (5-1)r8c1 = r8c2 - 1r1c24r1c9 - r2c8 = r9c8 - (4=5)r9c6 - r8c56 = (5-1)r8c1 = r8c2 - 1r1c2Naked Pair: in r1c2,r1c4 => r1c7<>4,r1c9<>4,WXYZ-Wing: 5679 in r1c579,r2c6,Pivot Cell Is r1c5 => r1c6<>9Almost Locked Set XY-Wing: A=r1c1579{15679}, B=r9c23468{345789}, C=r4789c1{12359}, X,Y=1, 9, Z=5 =>  r1c6<>5Region Forcing Chain: Each 7 in r9 true in turn will all lead r2c5<>37r9c2 - r6c2 = (7-4)r6c9 = r3c9 - (4=3)r2c8 - 3r2c5(7-9)r9c3 = (9-5)r9c1 = (5-4)r9c6 = r9c8 - (4=3)r2c8 - 3r2c57r9c4 - r2c4 = (7-3)r2c5Death Blossom Complex Type 2: Set have degrees of freedom of 1-34578{r2347c5} => r1c7<>93r3c5-(3=479){r136c9}5r3c5-(5=169){r1c156}3r7c5-(3=125689){r8c124567}AIC Type 2: 9r1c1 = (9-7)r1c9 = (7-4)r6c9 = r6c2 - r5c1 = 4r2c1 => r2c1<>9AIC Type 2: 5r8c1 = (5-9)r9c1 = r1c1 - (9=7)r1c9 - (7=5)r1c7 - (5=6)r1c5 - r8c5 = 6r8c6 => r8c6<>5Death Blossom Complex Type 2: Set have degrees of freedom of 2-12358{r8c124} => r2c8<>45r8c1-(5=34789){r9c12348}3r8c4-(3=46789){r2c13456}8r8c4-(8=349){r8c79,r9c8}Hidden Single: 4 in c8 => r9c8=4Full House: r2c8=3Naked Single: r9c6=5Hidden Single: 5 in b7 => r8c1=5Hidden Single: 1 in b7 => r8c2=1Locked Candidates 1 (Pointing): 4 in b3 => r3c2<>4,r3c4<>4Locked Candidates 1 (Pointing): 2 in b7 => r7c6<>2Locked Candidates 2 (Claiming): 2 in c2 => r3c3<>2Hidden Pair: 38 in r5c9,r8c9 => r8c9<>9Hidden Single: 9 in b9 => r8c7=9AIC Type 2: 2r1c2 = r1c4 - r3c6 = (2-6)r8c6 = r8c5 - (6=5)r1c5 - (5=7)r1c7 - r1c9 = (7-4)r6c9 = 4r6c2 => r1c2<>4Hidden Single: 4 in b1 => r2c1=4Hidden Single: 4 in b4 => r6c2=4Full House: r6c9=7Hidden Single: 7 in b3 => r1c7=7Hidden Single: 5 in b3 => r3c7=5Hidden Single: 4 in b3 => r3c9=4Full House: r1c9=9Hidden Single: 4 in b2 => r1c4=4Hidden Single: 5 in b2 => r1c5=5Hidden Single: 6 in c5 => r8c5=6Hidden Single: 9 in c1 => r9c1=9Hidden Single: 2 in r1 => r1c2=2Naked Single: r3c2=8Naked Single: r3c5=3Naked Single: r3c4=2Hidden Single: 2 in b8 => r8c6=2Skyscraper : 3 in r4c2,r7c1 connected by r47c7 => r5c1,r9c2 <> 3[stte]`

The second puzzle is essentially cracked with an early MSLS :

Code: Select all
`.2...67..4...8......9.......3.....7.5.8....4..1.3....2....9..5....6.1..3...2..6.7Hidden Single: 3 in b6 => r5c7=3Locked Candidates 1 (Pointing): 2 in b4 => r4c5<>2,r4c6<>2Locked Candidates 2 (Claiming): 4 in c2 => r7c3<>4,r8c3<>4,r9c3<>4MSLS:16 Cells r1689c1358, 16 Links 13r1,67r6,27r8,13r9,89c1,45c3,45c5,89c819 Eliminations: r1c49<>1,r8c7<>2,r9c6<>3,r346c5,r4c3,r6c6<>4,r34c5,r2c3<>5, r6c6,r8c2<>7,r3c18,r7c1<>8,r2c8,r4c1<>9Hidden Single: 4 in b4 => r6c3=4Locked Pair: in r4c1,r4c3 => r5c2<>6,r6c1<>6,r4c5<>6,r4c9<>6,Naked Single: r4c5=1Hidden Single: 1 in b6 => r5c9=1Hidden Single: 6 in b6 => r6c8=6Hidden Single: 6 in b5 => r5c5=6Hidden Single: 2 in b5 => r5c6=2Hidden Single: 2 in b2 => r3c5=22-String Kite: 8 in r6c7,r7c4 connected by r4c4,r6c6 => r7c7 <> 8Empty Rectangle : 7 in b8 connected by r6 => r7c1 <> 7Sue de Coq: r23c7 - {124589} (r23c8 - {123}, r468c7 -{4589}) =>  r1c8<>1 r1c8<>3 r7c7<>4Locked Candidates 2 (Claiming): 1 in r1 => r2c3<>1,r3c1<>1AIC Type 1: 4r3c7 = r8c7 - (4=8)r7c9 - r7c4 = (8-4)r4c4 = 4r4c6 => r3c6<>4 AIC Type 2: 4r3c7 = r8c7 - (4=8)r7c9 - r7c4 = r4c4 - r6c6 = 8r6c7 => r3c7<>8AIC Type 1: 4r4c6 = (4-8)r4c4 = r7c4 - (8=4)r7c9 => r7c6<>4 Grouped AIC Type 2: 9r2c6 = r46c6 - (9=7)r5c4 - (7=5)r6c5 - r89c5 = 5r9c6 => r2c6<>5Grouped AIC Type 2: 4r4c6 = (4-5)r9c6 = r89c5 - (5=7)r6c5 - (7=9)r5c4 => r4c6<>9Almost Locked Set XY-Wing: A=r7c49{478}, B=r469c6{4589}, C=r5c4{79}, X,Y=7, 9, Z=8 =>  r7c6<>8AIC Type 2: 3r1c5 = r9c5 - (3=7)r7c6 - r8c5 = r6c5 - (7=9)r6c1 - r6c6 = 9r2c6 => r2c6<>3Almost Locked Set XY-Wing: A=r19c3{135}, B=r7c7{12}, C=r2c234679{1235679}, X,Y=3, 2, Z=1 =>  r7c3<>1Almost Locked Set XY-Wing: A=r2c236789{1235679}, B=r23469c6{345789}, C=r3c8{13}, X,Y=1, 3, Z=7 =>  r2c4<>7Almost Locked Set XY-Wing: A=r6c167{5789}, B=r123c4,r1c5,r3c6{134579}, C=r5c4,r6c5{579}, X,Y=5, 9, Z=7 =>  r3c1<>7X-Wing:7c15\r68  => r8c3<>7AIC Type 2: 1r1c3 = r9c3 - r9c8 = (1-2)r7c7 = r8c8 - (2=5)r8c3 => r1c3<>5Locked Candidates 1 (Pointing): 5 in b1 => r8c2<>5,r9c2<>5AIC Type 2: 5r2c2 = (5-8)r3c2 = (8-6)r3c9 = 6r2c9 => r2c9<>5r2c2<>6AIC Type 1: (2=6)r4c1 - (6=3)r3c1 - r2c3 = (3-2)r2c8 = 2r8c8 => r8c1<>2 WXYZ-Wing: 4789 in r8c12,r6c1,r9c2,Pivot Cell Is r8c1 => r9c1<>9Hidden Pair: 79 in r6c1,r8c1 => r8c1<>8Uniqueness Test 7: 26 in r47c13; 2*biCell + 1*conjugate pairs(2c1) => r7c3 <> 6Sashimi X-Wing:8r38\c29 fr8c78 => r7c9<>8Naked Single: r7c9=4Hidden Single: 4 in b3 => r3c7=4Hidden Pair: 12 in r2c7,r7c7 => r2c7<>59Locked Candidates 2 (Claiming): 5 in c7 => r4c9<>5AIC Type 2: 4r1c4 = (4-3)r1c5 = r9c5 - (3=7)r7c6 - (7=9)r2c6 => r1c4<>9Locked Candidates 2 (Claiming): 9 in r1 => r2c9<>9Naked Single: r2c9=6Hidden Single: 6 in c3 => r4c3=6Hidden Single: 2 in b4 => r4c1=2AIC Type 2: (8=9)r1c8 - r9c8 = r9c2 - (9=7)r8c1 - r7c3 = (7-3)r2c3 = (3-2)r2c8 = 2r8c8 => r8c8<>8X-Wing:8c18\r19  => r9c26,r1c9<>8Hidden Single: 8 in b8 => r7c4=8W-Wing: 45 in r1c4,r9c6 connected by 4r4 => r3c6<>5Naked Pair: in r3c6,r7c6 => r2c6<>7,Naked Single: r2c6=9Locked Candidates 2 (Claiming): 7 in r2 => r3c2<>7XYZ-Wing: 489 in r8c2 r8c7 r9c2 => r8c1 <> 9[stte]`

The third puzzle has an early MSLS but remains unsolved without 'Brute Force'.
ghfick

Posts: 149
Joined: 06 April 2016

### Error Launching Web Browsers On Smart Tv

Please tell me, can anyone come across such an error
on Smart.
When you open web Browsers, it writes like this (photo in the attached file)
... What can you do ... Thank you
In search of love, xxx me somebody ) Krist_snowflakeFausy

Posts: 1
Joined: 01 October 2021
Location: Lithuania

### Re: The hardest sudokus (new thread)

Finished the last bit of rating I was doing for the update. I'm going to go through the thread in the next couple days to get puzzles from others.
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

I believe these are all the puzzles posted by someone other than me since the 2020-10 update:

jco
98.7.....7.6...9...5.......4..8..6......5..3......2..1..89..4......1...2.....3.5. ER/EP/ED=11,8/11,8/10,4
98.7.....7.6...8....5......4..6..9......3..5......2..1.9.4..7......1..3......5..2 ER/EP/ED=11,8/11,8/10,3
98.7.....7.6...8....5......4..8..9......3..5......2..1.9.6..4......5...2.....1.3. ER/EP/ED=11,8/11,8/3,4
98.7.....6.....5....4......7..8..9......3..4......2..1.5.9..6......4..3......1..2 ER/EP/ED=11,8/11,8/3,4
98.7.....7.6...8....5......8..6..4......5..3......2..1.7.4..9......1..2......3..5 ER/EP/ED=11,7/11,7/11,1
98.7.....7.6...9...5.......4..6..8......5..3......2..1..94..7......3...5.....1.2. ER/EP/ED=11,7/11,7/11,1
98.7.....7.6...8...5.......4..9..6......5..3......2..1..78..4......1..5......3..2 ER/EP/ED=11,7/11,7/10,7 (*)
98.7.....7.6...8....5......4..8..9......3..5......2..1.7.6..4......5...3.....1.2. ER/EP/ED=11,7/11,7/3,4
98.7.....7.6...8...5.......4..8..9......5..3......2..1..74..6......1..5......3..2 (ER/EP/ED=11,7/11,7/11,3) (*)
98.7.....7.6...5....4......5..6..7......4..3......2..1.7.8..9......1..2......3..4 (ER/EP/ED=11,7/11,7/10,6)
(these were "generated" with YZF and are just morphs of puzzles already in the database, but I will double-check that)

98.7.....6...5.8....4....3.7..9..5....3....4......2..1.6...1..2..9.........89.6.. 11.8/1.2/1.2
98.7.....6...8......5..4...3..8..9...7....86.....4...2.9.6..3....1.5.........2..1 11.7/11.7/8.0
98.7.....6..85......4..3....9..8.7.......2.1.........2.5..7.6....9...5....1....43 11.7/1.2/1.2
98.7..6..5..69.....4...8...3.....56..2......8..4.....2...97........3.7.......2.31 11.7/11.7/2.6
98.76.5..54.........75.4.9.7..4.9.5..9...5..3....2....4......81.7.9.8.4.......... 11.6/1.2/1.2
98.76.5..75.........4..5.978......3..4...9.58........24....8.7..9.2..38.....9.1.. 11.6/1.2/1.2
98.7.....7.6.5......4..3...2.5...4...9.....82...2....1.7.1...2......63.........19 11.6/11.6/2.6
98.7.....6..85......4..3....9..8.6....2.............32.5.6..7.......85.......1.24 11.6/1.2/1.2
98.7..6..5...9..84.........46..7.8....86....3..5..4....4...79....2.....8....8..1. 11.6/1.2/1.2
98.7..6..5...9..4......8...46..7.8....86...3...5..4....4...79....2....8.....8...1 11.6/1.2/1.2
98.7..6....7.5..98.........76.9....5..4..........37...5..6...8...2...7.6....715.. 11.6/1.2/1.2
98.76....5....49....3......4....5.9..7......5..5...2.41....9..2..6.8.......3...1. 11.6/11.6/2.6
98.76....5.....7.......5.987.....4...9.....83..32.....3....9.57.5..7..3.......1.. 11.6/1.2/1.2
98.76.5..54....7.....5...848..9....7.7..5..........32..9.4...75....1.2........... 11.6/1.2/1.2
98.76....54....7.....5...848..9...57.7..5..........32..9.4...75....1.2........... 11.6/1.2/1.2
98.7..6..5.46.........9..837..9..5......2...7.....6.4.1....9.7..5..671.....1....5 11.6/1.2/1.2
98.7.......6.5.4.......6...8..4...7..7......3..2..71...9.3....4..1.6.........25.. SER = 11.7/11.7/4.3
98.7..6..7...9......5..4...3...7.8....9..6.42.....1....9..6.3....2.............15 SER = 11.6/11.6/2.6
98.7..6....5.9...........4.79....3....6..3........7.6236...98....1.8.......6..... SER = 11.6/1.2/1.2
98.7..6..7..6..5......4..8.5..9..7...7...3....6......21.......5.9...71.....1...6. SER = 11.6/1.2/1.2
98.7..6..7..6..5......4..8.5..9..7...6......3.....2...1.......5.9...71....71...6. SER = 11.6/1.2/1.2

JPF
........1....12.....34...5.....6...2.7....53..8.5..4...378.....1....9...94....7..;11.8;1.2;1.2
........1....21.....34...5.....6...2.7....53..8.5..4...378.....6....9...94....7..;11.7;11.7;2.6
........1....21.....34...5.....6...2.7....53..8.5..4...378.....1....9...94....7..;11.3;1.2;1.2
........1....23.....45...6.....7...3.5....84..9.8..6...469.....2....1...18....4..;11.3;1.2;1.2
........1....21.....34...5.....6...2.7....53..8.3..4...378.....6....9...94....7..;11.3;1.2;1.2
........1....12.....34...5.....6...7.8....43..9.3..5...598.....2....7...73....9..;11.2;1.2;1.2
........1....23.....45...6.....7...2.5....48..8.4..6...659.....3....1...14....8..;11.1;1.2;1.2
........1....21.....34...5.....6...2.7....53..8.5..4...378.....9....6...64....7..;11.0;11.0;2.6
........1....12.....34...5.....6...2.4....37..7.3..5...548.....1....9...93....7..;11.0;1.2;1.2

999_Springs
(several non-minimals, will check all the minimals against the database)

Some of the above are already in my local database, but if I hadn't posted them here already I will update the "creator" field accordingly. Will scrape the patterns game later.
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

mith wrote:(these were "generated" with YZF and are just morphs of puzzles already in the database, but I will double-check that)

All these puzzles are taken from the database, so you don’t need to recheck .These puzzles are only provided for the convenience of players to learn JE, MSLS and other technologies.
yzfwsf

Posts: 422
Joined: 16 April 2019

### Re: The hardest sudokus (new thread)

That's what I suspected, but thank you for the confirmation mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

mith wrote:That's what I suspected, but thank you for the confirmation I should have deleted that listing as soon as mith made me aware that they were all known puzzles.
My interest at that time was on SK-loops (practicing to identify them), but got distracted/curious with the unusually
high (for me, at that time) ratings of that puzzles. Anyway, It was a mistake to post them and I should have deleted them as soon as I read mith's observation. Now I deleted that content (except the one after mith's observation, explaining basically the same
as above). My apologies.
JCO
jco

Posts: 309
Joined: 09 June 2020

### Re: The hardest sudokus (new thread)

No worries!
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

Our modem got zapped by lightning a few nights ago, so I've been occupied getting our internet back up. Will get back on this soon.
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

Haven't forgotten about this! I will definitely be getting the update out before next Thursday (having foot surgery and will have trouble getting to this computer for a few weeks after), but hopefully sooner.
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

I should stop committing to dates, life keeps getting in the way. In the meantime, I went ahead and pulled all my 10.6+ puzzles (which weren't in a previous update) along with 10.2+ for 19c, 35c, and 36c. You can view them here: https://drive.google.com/file/d/1DEYdwZ ... sp=sharing

Since I'm having surgery tomorrow and won't be able to get up to this computer for a while, I'm just going to go ahead and start my scripts running again and maybe there will be some nice surprises waiting when I check in a few weeks.
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

The above is a lot of puzzles (394844)! If all you care about is the 11.6+ puzzles, here are those (535): https://drive.google.com/file/d/1xjnXn1 ... sp=sharing
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

Here are all of the 11.6+ puzzles now in my database (1161 puzzles): https://drive.google.com/file/d/1_N6oN4 ... sp=sharing

(the last two numbers in each file are gsf's q1 and q2 respectively)
mith

Posts: 586
Joined: 14 July 2020

### Re: The hardest sudokus (new thread)

marek stefanik wrote:Hello everyone,

I came here looking for new sudoku techniques.

Very interesting puzzles, make me wonder what kind of magic would one have to use to prove this contradiction using truths and links (it's in every single one of these 30+-clue puzzles and I'm slowly going insane thinking about it ).

Code: Select all
`123   .    .  |  .    .   123 .   123   .  |  .   123   . .    .   123 | 123   .    .––––––––––––––+–––––––––––––– .    .   123 | 123   .    . .   123   .  |  .    .   123123   .    .  |  .   123   .`

In sukaku format: Show
123000000000456789000456789000456789000456789123000000123456789123456709123456780000456789123000000000456789000456789123000000000456789123456789123456709123456780000456789000456789123000000123000000000456789000456789123456789123456709123456780000456789000456789123000000123000000000456789000456789123456789123456709123456780000456789123000000000456789000456789000456789123000000123456789123456709123456780123000000000456789000456789000456789123000000000456789123456789123456709123456780123456789123456789123456789123456789123456789123456789123456700123456700123456700123456709123456709123456709123456709123456709123456709123456700000000080123456700123456780123456780123456780123456780123456780123456780123456700123456700000000009

Marek

Updating on this technique, ryokousha of the CTC discord came up with an elegant permutation parity argument, which generalizes nicely to other triplet patterns, and rangsk recorded a follow-up video to our series (the last episode of which featured a puzzle with this property), explaining the new approach (my approach in the episode amounted to “however one digit is placed, you are left with a bivalue oddagon on the other digits): https://youtu.be/V7RC1hJ8vZ8
mith

Posts: 586
Joined: 14 July 2020

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