The New Sudoku Players' Forum

by **jco** » Sat Dec 20, 2025 1:23 am

Code: Select all: +-------+-------+-------+ | . . 2 | 5 1 . | . 3 . | | . . . | . 3 . | 2 . . | | . . 6 | . 4 . | . . . | +-------+-------+-------+ | . 2 . | . . 6 | . . 5 | | . 4 . | . . . | . . . | | 8 . . | . 5 . | . . 7 | +-------+-------+-------+ | 4 . . | 9 . . | . 5 . | | . 3 7 | 1 . . | . . . | | . . . | . . 3 | 1 . . | +-------+-------+-------+ ..251..3.....3.2....6.4.....2...6..5.4.......8...5...74..9...5..371..........31..

(Source: Sudoku Architect)

by **pjb** » Sat Dec 20, 2025 5:32 am

Coldn't get a one step solution. Here's two:

1) (1)r2c1 = (1-7)r4c1 = (7-6)r5c1 = (6)r6c2 - (6=1)r7c2 => -1 r23c2

Code: Select all: 9 78 2 | 5 1 78 | 46 3 46 a15 578-1 4 | 6 3 789 | 2 789 189 3 78-1 6 | 28 4 2789 | 5 789 189 ------------------------+----------------------+--------------------- b17 2 139 | 378 89 6 | 3489 1489 5 c567 4 359 | 2378 289 1 | 3689 2689 2689 8 d169 139 | 23 5 4 | 369 1269 7 ------------------------+----------------------+--------------------- 4 e16 18 | 9 268 28 | 7 5 3 26 3 7 | 1 68 5 | 4689 24689 24689 256 569 589 | 4 7 3 | 1 268 268

2) (8=2)r7c6 - (2)r3c6 = (2-8)r3c4 = (8-3)r4c4 = (3*-2)r6c4 = (2-1)r6c8 = (1-4)r4c8 = (4^)r4c7 - (4=6#)r1c7 - (6|3*=9)r6c7 - (9|4^|6#=8)r8c7 => -8 r8c5

Code: Select all: 9 78 2 | 5 1 78 |i46 3 46 1 5 4 | 6 3 789 | 2 789 89 3 78 6 |c28 4 b2789 | 5 789 1 ------------------------+----------------------+--------------------- 7 2 139 |d38 89 6 |h3489 g1489 5 56 4 359 | 7 289 1 | 3689 2689 2689 8 169 139 |e23 5 4 |j369 f1269 7 ------------------------+----------------------+--------------------- 4 16 18 | 9 268 a28 | 7 5 3 26 3 7 | 1 6-8 |k4689 24689 24689 256 69 589 | 4 7 3 | 1 268 268

Phil

by **Cenoman** » Sat Dec 20, 2025 8:07 pm

Code: Select all: +---------------------+----------------------+-------------------------+ | 9 78 2 | 5 1 78 | 46 3 46 | | 15 1578 4 | 6 3 789 | 2 789 189 | | 3 178 6 | 28 4 2789 | 5 789 189 | +---------------------+----------------------+-------------------------+ | 17 2 139 | 378 89 6 | a3489 1489 5 | | 567 4 359 | 2378 Cc289 1 | a3689 b2689 b2689 | | 8 169 139 | B23 5 4 |Ab369 1269 7 | +---------------------+----------------------+-------------------------+ | 4 16 18 | 9 Dd28-6 28 | 7 5 3 | | 26 3 7 | 1 z68 5 | y4689 24689 24689 | | 256 569 589 | 4 7 3 | 1 268 268 | +---------------------+----------------------+-------------------------+

Kraken AAHS(38)r4568c7
(38)r45c7 - (3|8=692)b6p567 - r5c5 = (2)r7c5
(3)r6c7 - (3=2)r6c4 - r5c5 = (2)r7c5
(8)r8c7 - (8=6)r8c5
=> -6 r7c5; ste

by **jco** » Mon Dec 22, 2025 11:20 am

Thank you for your nice solutions !

For this puzzle I focused only on the boxes 1,2,3. Perhaps there is
a compact way to write the move as a DP [what I wrote is the deduction itself]

After basics,

Code: Select all: ,---------------------------------------------------------, | 9 (78) 2 | 5 1 (78) | 46 3 46 | | 15 1578 4 | 6 3 (789) | 2 (789) [1]89 | | 3 (78)[1] 6 | 28 4 (789)+2| 5 (789) 189 | |-----------------+------------------+--------------------| | 17 2 139 | 378 89 6 | 3489 1489 5 | | 567 4 359 | 2378 289 1 | 3689 2689 2689 | | 8 169 139 | 23 5 4 | 369 1269 7 | |-----------------+------------------+--------------------| | 4 16 18 | 9 268 28 | 7 5 3 | | 26 3 7 | 1 68 5 | 4689 24689 24689 | | 256 569 589 | 4 7 3 | 1 268 268 | '---------------------------------------------------------'

UR1(78)r13c26, DP1(78)r13c2,r12c6,r23c8, UR3(79)r23c68,DP2(789)r23c2,r123c6,r23c8

(1)r3c2|r2c9 - (1=578)b1p245 - (7|8|9=DP2=2)r3c6
||
[(2=UR1=9)r3c6 - (9)r2c6|r3c8 =DP1= (9)r2c8 - (9=8)r2c9 - (8)r2c68|r3c8 = (79)r2c68,r3c8 - (7|9|8=UR3,1=2)r2c6]

=> +2 r3c6; ste

by **totuan** » Mon Dec 22, 2025 3:11 pm

jco wrote:For this puzzle I focused only on the boxes 1,2,3. Perhaps there is a compact way to write the move as a DP [what I wrote is the deduction itself]

Nice find! My view for this one:

Code: Select all: *--------------------------------------------------------------------* | 9 AB78 2 | 5 1 AB78 | 46 3 46 | |#15 B78+15 4 | 6 3 AB789 | 2 AB789 A89+1 | | 3 A78+1 6 | 28 4 AB789+2 | 5 AB789 B89+1 | |----------------------+----------------------+----------------------| | 17 2 139 | 378 89 6 | 3489 1489 5 | | 567 4 359 | 2378 289 1 | 3689 2689 2689 | | 8 169 139 | 23 5 4 | 369 1269 7 | |----------------------+----------------------+----------------------| | 4 16 18 | 9 268 28 | 7 5 3 | | 26 3 7 | 1 68 5 | 4689 24689 24689 | | 256 569 589 | 4 7 3 | 1 268 268 | *--------------------------------------------------------------------*

Two DB-A&B(789) marked cells => A: (2)r3c6=(1)r2c9,r3c2, B: (15)r2c2,r3c9=(2)r3c6
(2)r3c6==(15)r2c19,r3c2-(15)r2c2,r3c9==(2)r3c6 => r3c6<>789, stte

The simple way to prove for DB-A&B

Code: Select all: A=(8|9) *-----------------------------------------------------------* | . 78 . | . . 78 | . . . | | . . . | . . 789 | . 789 A89 | | . 78 . | . . 789 | . 789 . | *-------------------+-------------------+-------------------* A=8 => two UR: UR(78)r13c26 & UR(79)r23c68 A=9 => MUG(78)r13c2,r12c6,r23c8 => Impossible B=(8|9) *-------------------+-------------------+-------------------* | . 78 . | . . 78 | . . . | | . 78 . | . . 789 | . 789 . | | . . . | . . 789 | . 789 B89 | *-----------------------------------------------------------* The same as above

Thanks for the puzzle!
totuan

by **eleven** » Mon Dec 22, 2025 4:27 pm

Very nice !
This pattern is deadly, because by the 4 and 6 cell URs 78 9 has to go to r2c6 and r3c8, and then r2c8 and r3c6 must be the same digit 7 or 8.

Code: Select all: | . 78 . | . . 78 | . . . | | . 78 . | . . 789 | . 789 . | | . . . | . . 789 | . 789 . |

Then also this is deadly, because r2c12 have to be 15, and you get the same pattern with rows 23 switched.

Code: Select all: | . 78 . | . . 78 | . . . | | 15 1578 . | . . 789 | . 789 . | | . 178 . | . . 789 | . 789 . |

The New Sudoku Players' Forum

SE = 7.2

SE = 7.2

Re: SE = 7.2

Re: SE = 7.2

Re: SE = 7.2

Re: SE = 7.2

Re: SE = 7.2