The New Sudoku Players' Forum

by **Leren** » Tue Jul 13, 2021 9:40 am

Code: Select all: *-----------* |...|...|18.| |..6|...|4.2| |4..|.38|.6.| |---+---+---| |...|39.|...| |.8.|.54|...| |3..|7..|6.9| |---+---+---| |.2.|.45|...| |..1|...|5.7| |...|...|...| *-----------* ......18...6...4.24...38.6....39.....8..54...3..7..6.9.2..45.....1...5.7.........

by **P.O.** » Tue Jul 13, 2021 4:28 pm

Code: Select all: after singles + intersection on 7: b+2579 579 2579 4 267 2679 1 8 3 8 3 6 5 1 79 4 79 2 4 1 c-279 d+29 3 8 79 6 5 1 4567 2457 3 9 26 278 2457 48 a-2679 8 279 ×26 5 4 237 237 1 3 45 245 7 8 1 6 245 9 679 2 3789 169 4 5 389 139 68 69 469 1 8 26 2369 5 2349 7 569 4569 34589 1269 267 23679 2389 12349 468 depth: 1 candidate: 2 from cell (((5 4 5) (2 6))) ((2 0) (5 1 4) (2 6 7 9)) ((2 0) (1 1 1) (2 5 7 9)) ((2 1 1) (3 4 2) (2 9))) intersection on 9 ste.

by **Ngisa** » Tue Jul 13, 2021 9:01 pm

Code: Select all: +--------------------+------------------------+----------------------+ |b29 79 5 | 4 c267 c2679 | 1 8 3 | | 8 3 6 | 5 1 79 | 4 79 2 | | 4 1 279 |d29 3 8 | 79 6 5 | +--------------------+------------------------+----------------------+ | 1 67 247 | 3 9 26 | 278 5 48 | |a269 8 279 | 2-6 5 4 | 237 237 1 | | 3 5 24 | 7 8 1 | 6 24 9 | +--------------------+------------------------+----------------------+ | 7 2 38 | 169 4 5 | 389 139 68 | | 69 469 1 | 8 26 2369 | 5 2349 7 | | 5 469 38 | 1269 267 23679 | 2389 12349 468 | +--------------------+------------------------+----------------------+

(2)r5c1 = r1c1 – r1c56 = (2)r3c4 => - 2r5c4; stte

Clement

by **RSW** » Tue Jul 13, 2021 9:31 pm

Code: Select all: +-------------+----------------+----------------+ |f29 79 5 | 4 267 2679 | 1 8 3 | | 8 3 6 | 5 1 79 | 4 79 2 | | 4 1 e279 |d29 3 8 | 79 6 5 | +-------------+----------------+----------------+ | 1 67 247 | 3 9 26 | 278 5 48 | |b269 8 279 |c26 5 4 | 237 237 1 | | 3 5 24 | 7 8 1 | 6 24 9 | +-------------+----------------+----------------+ | 7 2 38 | 169 4 5 | 389 139 68 | |a6-9 469 1 | 8 26 2369 | 5 2349 7 | | 5 469 38 | 1269 267 23679 | 2389 12349 468 | +-------------+----------------+----------------+

(6)r8c1 = r5c1 - (6=2)r5c4 - r3c4 = r3c3 - (2=9)r1c1 => -9r8c1; ste

by **pjb** » Tue Jul 13, 2021 9:55 pm

Code: Select all: b29 79 5 | 4 267 2679 | 1 8 3 8 3 6 | 5 1 79 | 4 79 2 4 1 c279 |d29 3 8 | 79 6 5 ------------------------+----------------------+--------------------- 1 67 247 | 3 9 26 | 278 5 48 29-6 8 279 |e26 5 4 | 237 237 1 3 5 24 | 7 8 1 | 6 24 9 ------------------------+----------------------+--------------------- 7 2 38 | 169 4 5 | 389 139 68 a69 469 1 | 8 26 2369 | 5 2349 7 5 469 38 | 1269 267 23679 | 2389 12349 468

(6=9)r8c1 - (9=2)r1c1 - (2)r3c3 = (2)r3c4 - (2=6)r5c4 => -6 r5c1; stte

Phil

Website · by **denis_berthier** » Fri Jul 16, 2021 4:29 am

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Code: Select all: Resolution state after Singles and whips[1]: +-------------------+-------------------+-------------------+ ! 2579 579 2579 ! 4 267 2679 ! 1 8 3 ! ! 8 3 6 ! 5 1 79 ! 4 79 2 ! ! 4 1 279 ! 29 3 8 ! 79 6 5 ! +-------------------+-------------------+-------------------+ ! 1 4567 2457 ! 3 9 26 ! 278 2457 48 ! ! 2679 8 279 ! 26 5 4 ! 237 237 1 ! ! 3 45 245 ! 7 8 1 ! 6 245 9 ! +-------------------+-------------------+-------------------+ ! 679 2 3789 ! 169 4 5 ! 389 139 68 ! ! 69 469 1 ! 8 26 2369 ! 5 2349 7 ! ! 569 4569 34589 ! 1269 267 23679 ! 2389 12349 468 ! +-------------------+-------------------+-------------------+

===> There are 10 W1-anti-backdoors:
n9r1c2 n2r3c3 n9r3c4 n7r4c2 n6r4c6 n2r5c1 n6r5c1 n9r5c3 n2r5c4 n9r8c1

The simplest two 1-step solutions are;

Code: Select all: biv-chain[2]: r3n2{c4 c3} - c1n2{r1 r5} ==> r5c4 ≠ 2 w1tte

Code: Select all: biv-chain[3]: r5c4{n6 n2} - r3n2{c4 c3} - c1n2{r1 r5} ==> r5c1 ≠ 6, r5c4 ≠ 2 w1tte

Leren's Puzzles 54