original:
5, , , ,9, , , ,3,
,3, ,5, ,8, ,9, ,
,6, , , , , ,5, ,
1, , ,3, ,9, , ,7,
, , , ,4, , , , ,
2, , ,8, ,5, , ,1,
,2, , , , , ,7, ,
,9, ,6, ,3, ,8, ,
6, , , ,7, , , ,9,
stuck at:
5, [1478],[12478],[247],9,6,[12478],[124],3,
[47],3,[247],5,1,8,[2467]9,[246],
[89],6,[124789],[247],3,[247],[12478],5,[248],
1,[45],[456],3,2,9,[458],[46],7,
[389],[58],[35689],[17],4,[17],[23589],[236],[2568],
2,[47],[3479],8,6,5,[349],[34],1,
[38],2,[1345],9,8,[14],[1345],7,[456],
[47],9,[147],6,5,3,[124],8,[24],
6,[1458],[13458],[124],7,[124],[1345],[134],9,
any guidance would be appreciated.thanks. [/code]
badly stuck on Sunday Times
8 posts
• Page 1 of 1
badly stuck on Sunday Times
by mjo1943 » Wed Feb 08, 2006 7:51 pm
- mjo1943
- Posts: 5
- Joined: 13 March 2005
by TKiel » Wed Feb 08, 2006 7:59 pm
I believe the starting grid and initial candidate listing is as follows:
Tracy
- Code: Select all
*-----------*
|5..|.9.|..3|
|.3.|5.8|.9.|
|.6.|...|.5.|
|---+---+---|
|1..|3.9|..7|
|...|.4.|...|
|2..|8.5|..1|
|---+---+---|
|.2.|...|.7.|
|.9.|6.3|.8.|
|6..|.7.|..9|
*-----------*
*-----------------------------------------------------------------------------*
| 5 1478 12478 | 1247 9 12467 | 124678 1246 3 |
| 47 3 1247 | 5 126 8 | 12467 9 246 |
| 4789 6 124789 | 1247 123 1247 | 12478 5 248 |
|-------------------------+-------------------------+-------------------------|
| 1 458 4568 | 3 26 9 | 24568 246 7 |
| 3789 578 356789 | 127 4 1267 | 235689 236 2568 |
| 2 47 34679 | 8 6 5 | 3469 346 1 |
|-------------------------+-------------------------+-------------------------|
| 348 2 13458 | 149 158 14 | 13456 7 456 |
| 47 9 1457 | 6 125 3 | 1245 8 245 |
| 6 1458 13458 | 124 7 124 | 12345 1234 9 |
*-----------------------------------------------------------------------------*
Tracy
- TKiel
- Posts: 209
- Joined: 05 January 2006
by Carcul » Wed Feb 08, 2006 8:18 pm
Hi Mjo1943.
R7c1 should be "34": then the naked pair on column 1 eliminate the "4" from r7c1. You can also eliminate the "6" from r5c9. Next you have some locked candidates in box 9, and after that a X-Wing.
Regards, Carcul
R7c1 should be "34": then the naked pair on column 1 eliminate the "4" from r7c1. You can also eliminate the "6" from r5c9. Next you have some locked candidates in box 9, and after that a X-Wing.
Regards, Carcul
- Carcul
- Posts: 724
- Joined: 04 November 2005
by TKiel » Mon Feb 13, 2006 9:42 pm
mjo1943,
An x-wing is a pattern. There must be two rows, each row must have only two cells with the candidate and those two cells must be in the same two columns. Since there are only two places in each row where that candidate can be, if one is true the other must be false. The following grid is not from your puzzle but it does contain an x-wing in 9.
Row 1 has two cells and only two, with candidate 9, c2 and c9; row 9 has two cells, and only two, with candidate 9, c2 and c9. Two rows, two cells, two columns. If r1c2 is true, r1c9 & r9c2 must be false and r9c9 must be true. If r1c9 is true, r1c2 & r9c9 must be false and r9c2 must be true. Basically the shape is a rectangle. Imagine lines connecting opposite corners of the rectangle, like an X. The cells on the end of one of the lines is true and the other is false. If r1c2 is 9, that placement means that row 1 has a 9 and column 2 has a 9 and no other cells in either row 1 or column 2 can be 9. If r1c2 is 9, then we also know that r9c9 is 9 (opposite corners of the diagonal are the same). That placement means that row 9 has a 9 and column 9 has a 9 and no other cell in row 9 or column 9 can be a 9.
So what happens if we assign 9 to any other cell in column 2, lets say r2c2. The value 9 candidates disappear from the rest of the cells in column 2. Now the only cell for row 1 that can possibly be a 9 is r1c9 and the only cell in row 9 that can be a 9 is r9c9. If we assign r1c9 as 9 then row 9 has no cell that can possibly be 9, which we know can't be correct. Basically, once the conditions of the x-wing are met (two rows, two cells, two columns) the assignment of that value to any cell besides the four that make up the x-wing, means that one row or column will not have that value.
Once you find the x-wing, all other cells in the two column that contain the x-wing value, except for the four cells that make up the x-wing, can have that value excluded. You can also have an x-wing is columns and the exclusions then occur in the rows.
Tracy
An x-wing is a pattern. There must be two rows, each row must have only two cells with the candidate and those two cells must be in the same two columns. Since there are only two places in each row where that candidate can be, if one is true the other must be false. The following grid is not from your puzzle but it does contain an x-wing in 9.
- Code: Select all
*------------------------------------------------------------*
| 47 249 1 | 8 5 3 | 6 247 249 |
| 5 369 789 | 2 4 16 | 1789 378 19 |
| 3468 2346 28 | 7 9 16 | 18 23458 1245 |
|----------------------+------------------+------------------|
| 9 7 3 | 1 2 8 | 5 46 46 |
| 2 8 5 | 9 6 4 | 3 1 7 |
| 16 16 4 | 5 3 7 | 2 9 8 |
|--------------------+------------------+--------------------|
| 3478 2349 2789 | 46 1 5 | 789 2678 269 |
| 1478 1245 278 | 46 78 9 | 178 25678 3 |
| 178 159 6 | 3 78 2 | 4 578 159 |
*------------------------------------------------------------*
Row 1 has two cells and only two, with candidate 9, c2 and c9; row 9 has two cells, and only two, with candidate 9, c2 and c9. Two rows, two cells, two columns. If r1c2 is true, r1c9 & r9c2 must be false and r9c9 must be true. If r1c9 is true, r1c2 & r9c9 must be false and r9c2 must be true. Basically the shape is a rectangle. Imagine lines connecting opposite corners of the rectangle, like an X. The cells on the end of one of the lines is true and the other is false. If r1c2 is 9, that placement means that row 1 has a 9 and column 2 has a 9 and no other cells in either row 1 or column 2 can be 9. If r1c2 is 9, then we also know that r9c9 is 9 (opposite corners of the diagonal are the same). That placement means that row 9 has a 9 and column 9 has a 9 and no other cell in row 9 or column 9 can be a 9.
So what happens if we assign 9 to any other cell in column 2, lets say r2c2. The value 9 candidates disappear from the rest of the cells in column 2. Now the only cell for row 1 that can possibly be a 9 is r1c9 and the only cell in row 9 that can be a 9 is r9c9. If we assign r1c9 as 9 then row 9 has no cell that can possibly be 9, which we know can't be correct. Basically, once the conditions of the x-wing are met (two rows, two cells, two columns) the assignment of that value to any cell besides the four that make up the x-wing, means that one row or column will not have that value.
Once you find the x-wing, all other cells in the two column that contain the x-wing value, except for the four cells that make up the x-wing, can have that value excluded. You can also have an x-wing is columns and the exclusions then occur in the rows.
Tracy
- TKiel
- Posts: 209
- Joined: 05 January 2006
sunday times puzzle
by mjo1943 » Wed Feb 15, 2006 6:38 pm
I have found the X wing -thank you Tracy- but am still stuck at:
5,[1478][2478],[247]9,6,[2478][124],3,
[47],3,[247],5,1,8,[2467],9,[246],
[89],6,[124789],[247],3,[24],[12478],5,[248],
1,[458],[4568],3,2,9,[458],[46],7,
[89],[58],[356789],1,4,7,[23589],[236],[258],
2,[47],[3479],8,6,5,[349],[34],1,
3,2,[45],9,8,1,[456],7,[456],
[47],9,[147],6,5,3,[124],8,[24],
6,[158],[58],[24],7,[24],,[35],[13],9,
and how do you get that layout that you used?
thanks again for the help (so far?) :?:
5,[1478][2478],[247]9,6,[2478][124],3,
[47],3,[247],5,1,8,[2467],9,[246],
[89],6,[124789],[247],3,[24],[12478],5,[248],
1,[458],[4568],3,2,9,[458],[46],7,
[89],[58],[356789],1,4,7,[23589],[236],[258],
2,[47],[3479],8,6,5,[349],[34],1,
3,2,[45],9,8,1,[456],7,[456],
[47],9,[147],6,5,3,[124],8,[24],
6,[158],[58],[24],7,[24],,[35],[13],9,
and how do you get that layout that you used?
thanks again for the help (so far?) :?:
- mjo1943
- Posts: 5
- Joined: 13 March 2005
by tarek » Wed Feb 15, 2006 6:53 pm
hi mjo1943,
from your pncilmarks, the next logical steps should be
Tarek
from your pncilmarks, the next logical steps should be
- Code: Select all
*--------------------------------------------------------------------------*
| 5 1478 2478 | 247 9 6 | 2478 124 3 |
| 47 3 247 | 5 1 8 | 2467 9 246 |
| 89 6 124789 | 247 3 24 | 12478 5 248 |
|------------------------+------------------------+------------------------|
| 1 458 4568 | 3 2 9 | 458 46 7 |
| 89 58 356789 | 1 4 7 | 23589 236 258 |
| 2 47 3479 | 8 6 5 | 349 34 1 |
|------------------------+------------------------+------------------------|
| 3 2 45 | 9 8 1 | 456 7 456 |
| 47 9 147 | 6 5 3 | 124 8 24 |
| 6 158 58 | 24 7 24 | 35 13 9 |
*--------------------------------------------------------------------------*
Eliminating 7 From r5c3 (Naked Single in Row 5)
*--------------------------------------------------------------------------*
| 5 1478 2478 | 247 9 6 | 2478 124 3 |
| 47 3 247 | 5 1 8 | 2467 9 246 |
|*89 6 -124789 | 247 3 24 |-12478 5 *248 |
|------------------------+------------------------+------------------------|
| 1 458 4568 | 3 2 9 | 458 46 7 |
|*89 -58 -35689 | 1 4 7 |-23589 236 *258 |
| 2 47 3479 | 8 6 5 | 349 34 1 |
|------------------------+------------------------+------------------------|
| 3 2 45 | 9 8 1 | 456 7 456 |
| 47 9 147 | 6 5 3 | 124 8 24 |
| 6 158 58 | 24 7 24 | 35 13 9 |
*--------------------------------------------------------------------------*
Eliminating 8 From r3c3 ( XWing in Columns 19)
Eliminating 8 From r3c7 ( XWing in Columns 19)
Eliminating 8 From r5c2 ( XWing in Columns 19)
Eliminating 8 From r5c3 ( XWing in Columns 19)
Eliminating 8 From r5c7 ( XWing in Columns 19)
Tarek
-
tarek - Posts: 3762
- Joined: 05 January 2006
8 posts
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