Sudoku Players' Forum (clone)

Code: Select all

.-------------------.----------------------.--------------------.
| 1     356    4    | 56       26    9     | 238    28     7    |
| 789   2      68   | 1467     3     167   | 489    5      14   |
| 3579  357    35   | 1457     247   8     | 6      1249   1234 |
:-------------------+----------------------+--------------------:
| 357   357    235  | 3678     2678  4     | 1      268    9    |
| 347   8      9    | 1367     5     12367 | 234    246    2346 |
| 6     1345   1235 | 1389     289   123   | 23458  7      2345 |
:-------------------+----------------------+--------------------:
| 2     3456   3568 | 3456789  1     3567  | 4579   469    456  |
| 458   9      1568 | 2        4678  567   | 457    3      1456 |
| 345   13456  7    | 34569    469   356   | 2459   12469  8    |
'-------------------'----------------------'--------------------'

Code: Select all

1.4..9..7.2..3..5......86.......41.9.89.5....6......7.2...1.....9.2...3...7.....8

Solvepath by Andrew Stuarts solver(www.sudokuwiki.org):

Code: Select all

Step 1 - Pointing Pairs  docs
PAIR: Between Box 4 and Row 6:
1 taken off F4
1 taken off F6
Step 2 - Pointing Pairs  docs
PAIR: Between Box 2 and Col 5:
2 taken off D5
2 taken off F5
Step 3 - Pointing Pairs  docs
PAIR: Between Box 2 and Col 4:
5 taken off G4
5 taken off J4
Step 4 - Pointing Pairs  docs
PAIR: Between Box 6 and Row 6:
5 taken off F2
5 taken off F3
Step 5 - Pointing Pairs  docs
PAIR: Between Box 1 and Row 2:
8 taken off B7
Step 6 - Exocet  docs
Some solution combinations in the two gray cells would empty at least one of the colored cells. Removing those combinations create eliminations in the gray cells.
Pair D8 / E1 reduced from 2/6/8->6/8 and 3/4/7->3/4/7
- Combinations of 2/3/5/7 found in ALS {D1,D2,D3}
- Combinations of 2/3/4/6 found in ALS {E7,E8,E9}
Step 7 - Hidden Singles  docs
2 found once at D3 in row, 2 candidates removed
Last candidate, 2, in D3 changed to solution
Step 8 - Y-Wing  docs
Y-Wing pattern. Hinge: A8 (2/8), wings A5 D8, therefore
6 can be taken off D5
Step 9 - Exocet  docs
Some solution combinations in the two gray cells would empty at least one of the colored cells. Removing those combinations create eliminations in the gray cells.
Pair D4 / D5 reduced from 3/6/7/8->6/7/8 and 7/8->7/8
- Pair 6/8 found in ALS {D8}
- Combinations of 3/5/7 found in ALS {D1,D2}
- Combinations of 3/8/9 found in ALS {F4,F5}
Step 10 - Naked Triple  docs
Naked Triple 6/7/8 in Row D, on cells [D4,D5,D8]
- removes 7 from D1
- removes 7 from D2


Can anyone explain steps 6 and 9 more in detail?

For step 6, my solver output is as follows:

Code: Select all

ALS Discontinuous Nice Loop: 2r4c3 = r4c8 - (8=2364)b6p2456 - (4=3572)b4p1234 => r4c3=2

For step 9, my solver output is as follows:

Code: Select all

ALS Discontinuous Nice Loop: 3r4c12 = r4c4 - (3=98)r6c45 - (8=573)r4c125 => r6c23,r4c4,r5c1<>3

it seems that these are APE deductions being put under the exocet name

.

Code: Select all

Resolution state after Singles and whips[1]:
   +----------------------+----------------------+----------------------+
   ! 1      356    4      ! 56     26     9      ! 238    28     7      !
   ! 789    2      68     ! 1467   3      167    ! 49     5      14     !
   ! 3579   357    35     ! 1457   247    8      ! 6      1249   1234   !
   +----------------------+----------------------+----------------------+
   ! 357    357    235    ! 3678   678    4      ! 1      268    9      !
   ! 347    8      9      ! 1367   5      12367  ! 234    246    2346   !
   ! 6      134    123    ! 389    89     23     ! 23458  7      2345   !
   +----------------------+----------------------+----------------------+
   ! 2      3456   3568   ! 346789 1      3567   ! 4579   469    456    !
   ! 458    9      1568   ! 2      4678   567    ! 457    3      1456   !
   ! 345    13456  7      ! 3469   469    356    ! 2459   12469  8      !
   +----------------------+----------------------+----------------------+
191 candidates.

Solution in Z5 (i.e. using only easy reversible chains):

Code: Select all

biv-chain[3]: r6n5{c9 c7} - c7n8{r6 r1} - b3n3{r1c7 r3c9} ==> r6c9≠3
biv-chain[3]: r9n2{c7 c8} - c8n1{r9 r3} - b3n9{r3c8 r2c7} ==> r9c7≠9
biv-chain[3]: r9n2{c7 c8} - r1c8{n2 n8} - b6n8{r4c8 r6c7} ==> r6c7≠2
biv-chain[4]: r2c9{n4 n1} - b9n1{r8c9 r9c8} - c2n1{r9 r6} - b4n4{r6c2 r5c1} ==> r5c9≠4
z-chain[5]: c9n3{r3 r5} - c9n2{r5 r6} - r6n5{c9 c7} - c7n8{r6 r1} - b3n3{r1c7 .} ==> r3c9≠4, r3c9≠1
     with z-candidates = n2r3c9 n3r3c9
naked-triplets-in-a-block: b3{r1c7 r1c8 r3c9}{n3 n8 n2} ==> r3c8≠2
biv-chain[4]: c6n2{r6 r5} - c6n1{r5 r2} - c9n1{r2 r8} - c3n1{r8 r6} ==> r6c3≠2
hidden-single-in-a-block ==> r4c3=2
biv-chain[3]: r4c8{n6 n8} - r1c8{n8 n2} - r1c5{n2 n6} ==> r4c5≠6
z-chain[4]: b6n3{r5c9 r6c7} - b6n8{r6c7 r4c8} - r4n6{c8 c4} - r4n3{c4 .} ==> r5c1≠3
     with z-candidates = n3r5c7 n3r4c2 n3r4c1
z-chain[4]: r4c5{n7 n8} - r4c8{n8 n6} - b5n6{r4c4 r5c4} - r5n1{c4 .} ==> r5c6≠7
     with z-candidates = n6r5c6 n1r5c6
finned-x-wing-in-rows: n7{r5 r2}{c1 c4} ==> r3c4≠7
biv-chain[4]: b6n8{r6c7 r4c8} - r4c5{n8 n7} - r5n7{c4 c1} - b4n4{r5c1 r6c2} ==> r6c7≠4
biv-chain[3]: r6n4{c9 c2} - r6n1{c2 c3} - r8n1{c3 c9} ==> r8c9≠4
biv-chain[4]: r6n4{c9 c2} - b4n1{r6c2 r6c3} - r8n1{c3 c9} - r2c9{n1 n4} ==> r7c9≠4
biv-chain[4]: r7c9{n6 n5} - b6n5{r6c9 r6c7} - b6n8{r6c7 r4c8} - r4n6{c8 c4} ==> r7c4≠6
biv-chain[4]: r6n4{c2 c9} - b6n5{r6c9 r6c7} - c7n8{r6 r1} - r1n3{c7 c2} ==> r6c2≠3
z-chain[4]: r4c5{n7 n8} - r4c8{n8 n6} - b5n6{r4c4 r5c6} - r5n1{c6 .} ==> r5c4≠7
     with z-candidates = n6r5c4 n1r5c4
stte

Nothing nearly as complicated as Exocets.