The New Sudoku Players' Forum

[dr-shaw]

Hi,

Just wondering what would be the next step and which technique to use.

10x

[Yogi]

You need to show us the puzzle at the point you have arrived at . . .

[dr-shaw]

You need to show us the puzzle at the point you have arrived at . . .

It won't let me upload the screenshot: "Sorry, the board attachment quota has been reached."

[dr-shaw]

Hi, I can't upload the screenshot it gives me an error with quota problem.

[dr-shaw]

Hi,

I will try to put the sudoku puzzle by text here:

123456789
A|--8|---|--3
B|--4|--9|---
C|-2-|37-|5--
D|-19|2--|--4
E|---|5--|2--
F|---|-3-|--6
G|-6-|--3|7--
H|79-|--8|---
I|8--|7--|-1-

[urhegyi]

Code: Select all

 . . 8 . . . . . 3
 . . 4 . . 9 . . .
 . 2 . 3 7 . 5 . .
 . 1 9 2 . . . . 4
 . . . 5 . . 2 . .
 . . . . 3 . . . 6
 . 6 . . . 3 7 . .
 7 9 . . . 8 . . .
 8 . . 7 . . . 1 .

[dr-shaw]

Code: Select all

 . . 8 . . . . . 3
 . . 4 . . 9 . . .
 . 2 . 3 7 . 5 . .
 . 1 9 2 . . . . 4
 . . . 5 . . 2 . .
 . . . . 3 . . . 6
 . 6 . . . 3 7 . .
 7 9 . . . 8 . . .
 8 . . 7 . . . 1 .

Thank you.
Any idea which technique will help find the next move?

[yzfwsf]

Code: Select all

Locked Candidates 1 (Pointing): 8 in b2 => r2c7<>8,r2c8<>8,r2c9<>8
Locked Candidates 1 (Pointing): 7 in b1 => r5c2<>7,r6c2<>7
Locked Candidates 2 (Claiming): 8 in c7 => r4c8<>8,r5c8<>8,r6c8<>8,r5c9<>8
Locked Candidates 1 (Pointing): 5 in b6 => r7c8<>5,r8c8<>5
Hidden Pair: 25 in r1c6,r9c6 => r1c6<>146,r9c6<>46
Finned X-Wing:6c36\r35 fr4c6 => r5c5<>6
AIC Type 2: (1=6)r2c7 - r9c7 = r9c5 - (6=8)r4c5 - r2c5 = 8r2c4 => r2c4<>1
Grouped W-Wing: 68 in r2c4,r4c5 connected by 6b8 => r2c5,r6c4<>8
Hidden Single: 8 in b2 => r2c4=8
2-String Kite: 6 in r1c4,r9c7 connected by b8p48 => r1c7 <> 6
AIC Type 1: (1=6)r2c7 - r9c7 = r9c5 - (6=8)r4c5 - r4c7 = (8-1)r6c7 = 1r5c9 => r23c9,r6c7<>1
Hidden Single: 1 in b6 => r5c9=1
Hidden Single: 7 in c9 => r2c9=7
Hidden Single: 7 in b1 => r1c2=7
Locked Candidates 1 (Pointing): 2 in b3 => r7c8<>2,r8c8<>2
2-String Kite: 9 in r5c8,r7c4 connected by b5p57 => r7c8 <> 9
Discontinuous Nice Loop: 8r4c5 = r4c7 - (8=9)r6c7 - r6c4 = (9-8)r5c5 = 8r4c5 => r4c5=8
Hidden Single: 8 in b6 => r6c7=8
Hidden Single: 8 in b4 => r5c2=8
Naked Single: r4c7=3
Hidden Single: 3 in b9 => r8c8=3
Locked Candidates 1 (Pointing): 6 in b5 => r3c6<>6
Locked Candidates 1 (Pointing): 6 in b9 => r2c7<>6
Naked Single: r2c7=1
Locked Candidates 1 (Pointing): 9 in b6 => r1c8<>9,r3c8<>9
XYZ-Wing: 356 in r2c1 r2c2 r4c1 => r1c1 <> 5
Locked Candidates 2 (Claiming): 5 in r1 => r2c5<>5
Naked Pair: in r2c5,r2c8 => r2c1<>6,
WXYZ-Wing: 3456 in r245c1,r6c2,Pivot Cell Is r5c1 => r6c1<>5
Uniqueness Test 7: 26 in r12c58; 2*biCell + 1*conjugate pairs(2c8) => r1c5 <> 6
Uniqueness Test 7: 25 in r19c56; 2*biCell + 1*conjugate pairs(5r1) => r9c5 <> 2
AIC Type 1: (6=5)r4c1 - (5=3)r2c1 - r5c1 = (3-6)r5c3 = 6r3c3 => r13c1,r5c3<>6
Hidden Single: 6 in b1 => r3c3=6
Locked Candidates 1 (Pointing): 1 in b1 => r7c1<>1
Naked Pair: in r3c8,r7c8 => r1c8<>4,
Uniqueness Test 1: 26 in r12c58 => r1c5 <> 26
Discontinuous Nice Loop: (6=5)r4c1 - r4c8 = (5-9)r6c8 = (9-1)r6c4 = r6c6 - (1=4)r3c6 - r3c8 = r7c8 - r7c1 = (4-3)r9c2 = r9c3 - r5c3 = (3-6)r5c1 = 6r4c1 => r4c1=6
Hidden Single: 6 in b5 => r5c6=6
Hidden Single: 5 in r4 => r4c8=5
Full House: r4c6=7
2-String Kite: 4 in r5c5,r9c2 connected by b4p48 => r9c5 <> 4
Dual Empty Rectangle : 4 in b3 connected by r9,c6 => r6c2 <> 4
Hidden Single: 4 in c2 => r9c2=4
Hidden Single: 3 in b7 => r9c3=3
Hidden Single: 3 in b4 => r5c1=3
Hidden Single: 4 in b4 => r6c1=4
Hidden Single: 4 in b5 => r5c5=4
Hidden Single: 9 in b5 => r6c4=9
Full House: r6c6=1
Hidden Single: 9 in b6 => r5c8=9
Full House: r5c3=7
Full House: r6c8=7
Hidden Single: 2 in b4 => r6c3=2
Full House: r6c2=5
Full House: r2c2=3
Hidden Single: 2 in b7 => r7c1=2
Hidden Single: 5 in b1 => r2c1=5
Hidden Single: 4 in c6 => r3c6=4
Hidden Single: 4 in b3 => r1c7=4
Hidden Single: 4 in b9 => r7c8=4
Hidden Single: 8 in b9 => r7c9=8
Hidden Single: 4 in b8 => r8c4=4
Hidden Single: 8 in b3 => r3c8=8
Hidden Single: 9 in b3 => r3c9=9
Full House: r3c1=1
Full House: r1c1=9
Hidden Single: 9 in b9 => r9c7=9
Full House: r8c7=6
Hidden Single: 6 in b8 => r9c5=6
Hidden Single: 9 in b8 => r7c5=9
Hidden Single: 6 in b2 => r1c4=6
Full House: r7c4=1
Full House: r7c3=5
Full House: r8c3=1
Hidden Single: 6 in b3 => r2c8=6
Full House: r2c5=2
Full House: r1c8=2
Hidden Single: 2 in b8 => r9c6=2
Full House: r9c9=5
Full House: r1c6=5
Full House: r1c5=1
Full House: r8c5=5
Full House: r8c9=2


[dr-shaw]

This solution is jibberish to me.
I'm new to this forum.
How do I decipher the meaning of this?

[Yogi]

Most of the solvers will convert the puzzles to a code which you can export from your program and copy to a post in this forum.
Others here can then import the code into their solver in order to look at it. Yours looks like this:
..8.....3..4..9....2.37.5...192....4...5..2......3...6.6...37..79...8...8..7...1.
Or
008000003004009000020370500019200004000500200000030006060003700790008000800700010

If you prefer the more pictorial image, again most solvers will export something like this:

+---+---+---+
|..8|...|..3|
|..4|..9|...|
|.2.|37.|5..|
+---+---+---+
|.19|2..|..4|
|...|5..|2..|
|...|.3.|..6|
+---+---+---+
|.6.|..3|7..|
|79.|..8|...|
|8..|7..|.1.|
+---+---+---+

Which is a bit difficult to relate to, but when you insert it into the forum’s CODE function in a post it aligns the characters to make it more readable:

Code: Select all

+---+---+---+
|..8|...|..3|
|..4|..9|...|
|.2.|37.|5..|
+---+---+---+
|.19|2..|..4|
|...|5..|2..|
|...|.3.|..6|
+---+---+---+
|.6.|..3|7..|
|79.|..8|...|
|8..|7..|.1.|
+---+---+---+


What happens next depends a bit where you are at. The puzzle you are working on may be far too difficult for you at present, especially if you are unfamiliar with the terms in yzfwsf’s explanation. Also, are you working with pencil & paper or on an electronic device which calculates the candidates? You could try googling ‘Solving Technique – Sudopedia Mirror’ for more ideas.

[eleven]

This is a very long puzzle (and therefore boring for me). I counted 7 short chains to be able to solve it.
The first one (after applying the hidden pair and locked candidates) is:

Code: Select all

+----------------------+----------------------+----------------------+
| 1569   57     8      | 146    12456  25     | 1469   24679  3      |
| 1356   357    4      | 168    12568  9      |a16     267    127    |
| 169    2      16     | 3      7      146    | 5      4689   189    |
+----------------------+----------------------+----------------------+
| 356    1      9      | 2     d68     67     |e38     357    4      |
| 346    348    367    | 5      14689  1467   | 2      379    179    |
| 245    458    257    | 1489   3      147    |f89-1   579    6      |
+----------------------+----------------------+----------------------+
| 1245   6      125    | 149    12459  3      | 7      2489   2589   |
| 7      9      1235   | 146    12456  8      | 346    2346   25     |
| 8      345    235    | 7     c24569  25     |b3469   1      259    |
+----------------------+----------------------+----------------------+

(1=6)r2c7 - r9c7 = r9c5 - (6=8)r4c6 - r4c7 = 8r6c7 => -1r6c7
This means: If r2c7 is not 1, it must be 6, then r9c7 can't be 6 and r9c5 must be 6, r4c6 can't be 6 and must be 8, r4c7 can't be 8, and r6c7 must be 8.
So you have: Either r2c7 is 1 or r6c7 is 8. In both cases r6c7 can't be 1 (and you must have 1 in r5c9).

Do you really want to see a full solution ? There are some free solvers, which can show you more or less optimized ones.

[denis_berthier]

.
This puzzle (SER = 8.2) can be solved using only Subsets and short elementary reversible chains (bivalue chains and z-chains).
The following resolution path can probably be made shorter by using longer chains, but I didn't try.

Code: Select all

Resolution state after Singles and whips[1]:
   +-------------------+-------------------+-------------------+
   ! 1569  57    8     ! 146   12456 12456 ! 1469  24679 3     !
   ! 1356  357   4     ! 168   12568 9     ! 16    267   127   !
   ! 169   2     16    ! 3     7     146   ! 5     4689  189   !
   +-------------------+-------------------+-------------------+
   ! 356   1     9     ! 2     68    67    ! 38    357   4     !
   ! 346   348   367   ! 5     14689 1467  ! 2     379   179   !
   ! 245   458   257   ! 1489  3     147   ! 189   579   6     !
   +-------------------+-------------------+-------------------+
   ! 1245  6     125   ! 149   12459 3     ! 7     2489  2589  !
   ! 7     9     1235  ! 146   12456 8     ! 346   2346  25    !
   ! 8     345   235   ! 7     24569 2456  ! 3469  1     259   !
   +-------------------+-------------------+-------------------+
190 candidates.

Code: Select all

hidden-pairs-in-a-column: c6{n2 n5}{r1 r9} ==> r9c6≠6, r9c6≠4, r1c6≠6, r1c6≠4, r1c6≠1
finned-x-wing-in-columns: n6{c3 c6}{r3 r5} ==> r5c5≠6
biv-chain[3]: r4c7{n3 n8} - r4c5{n8 n6} - r9n6{c5 c7} ==> r9c7≠3
whip[1]: r9n3{c3 .} ==> r8c3≠3
whip[3]: r2n8{c4 c5} - r4c5{n8 n6} - b8n6{r8c5 .} ==> r2c4≠6
finned-x-wing-in-columns: n6{c4 c8}{r8 r1} ==> r1c7≠6
biv-chain[4]: r2c7{n1 n6} - r9n6{c7 c5} - r4c5{n6 n8} - b6n8{r4c7 r6c7} ==> r6c7≠1
singles ==> r5c9=1, r2c9=7, r1c2=7
whip[1]: c9n2{r9 .} ==> r7c8≠2, r8c8≠2
finned-x-wing-in-rows: n9{r5 r9}{c5 c8} ==> r7c8≠9
biv-chain[3]: r5n8{c2 c5} - r5n9{c5 c8} - r6c7{n9 n8} ==> r6c2≠8
hidden-single-in-a-block ==> r5c2=8
biv-chain[3]: r6c2{n5 n4} - b7n4{r9c2 r7c1} - c1n2{r7 r6} ==> r6c1≠5
z-chain[3]: b7n4{r7c1 r9c2} - r6c2{n4 n5} - b1n5{r2c2 .} ==> r7c1≠5
biv-chain[4]: b5n8{r4c5 r6c4} - r2c4{n8 n1} - r2c7{n1 n6} - r9n6{c7 c5} ==> r4c5≠6
singles ==> r4c5=8, r4c7=3, r8c8=3, r2c4=8, r6c7=8
whip[1]: b6n9{r6c8 .} ==> r1c8≠9, r3c8≠9
whip[1]: b9n6{r9c7 .} ==> r2c7≠6
naked-single ==> r2c7=1
whip[1]: b5n6{r5c6 .} ==> r3c6≠6
biv-chain[3]: b4n3{r5c1 r5c3} - b7n3{r9c3 r9c2} - c2n4{r9 r6} ==> r5c1≠4
whip[1]: r5n4{c6 .} ==> r6c4≠4, r6c6≠4
hidden-pairs-in-a-column: c1{n2 n4}{r6 r7} ==> r7c1≠1
whip[1]: b7n1{r8c3 .} ==> r3c3≠1
naked-single ==> r3c3=6
naked-pairs-in-a-block: b1{r2c1 r2c2}{n3 n5} ==> r1c1≠5
whip[1]: r1n5{c6 .} ==> r2c5≠5
naked-pairs-in-a-column: c8{r3 r7}{n4 n8} ==> r1c8≠4
z-chain[3]: c4n4{r8 r1} - c4n6{r1 r8} - r8c7{n6 .} ==> r8c5≠4
biv-chain[4]: r1c1{n1 n9} - r1c7{n9 n4} - r8n4{c7 c4} - c4n6{r8 r1} ==> r1c4≠1
biv-chain[4]: r8n4{c4 c7} - b3n4{r1c7 r3c8} - r3c6{n4 n1} - r6n1{c6 c4} ==> r8c4≠1
naked-pairs-in-a-column: c4{r1 r8}{n4 n6} ==> r7c4≠4
naked-pairs-in-a-row: r8{c4 c7}{n4 n6} ==> r8c5≠6
z-chain[3]: r5c5{n9 n4} - b8n4{r7c5 r8c4} - b8n6{r8c4 .} ==> r9c5≠9
whip[1]: r9n9{c9 .} ==> r7c9≠9
biv-chain[4]: r9n9{c9 c7} - r9n6{c7 c5} - r2c5{n6 n2} - c6n2{r1 r9} ==> r9c9≠2
biv-chain[4]: r4n7{c6 c8} - b6n5{r4c8 r6c8} - r6n9{c8 c4} - r6n1{c4 c6} ==> r6c6≠7
stte

[dr-shaw]

Thank you very much for the input.
Since this entire code is new to me.
I saw you've written you used something called a chain.
I'm not familiar with this technique.
Can you refer me to a video or explanation with screenshots so I will understand better how these chains work?

[denis_berthier]

Thank you very much for the input.
Since this entire code is new to me.
I saw you've written you used something called a chain.
I'm not familiar with this technique.
Can you refer me to a video or explanation with screenshots so I will understand better how these chains work?

The various types of chains I've defined are described at length in my books and in CSP-Rules User Manual (all freely available), where you can also find graphical representations.
I have no video and I'll never make any. I consider all the videos I've seen as perfect sleeping pills.

[eleven]

Can you refer me to a video or explanation with screenshots so I will understand better how these chains work?

Look for sudoku alternate/alternating inference chains (AIC) or the simpler xy-chains/bivalue chains (only 2 candidates per cell).