Sudoku Players' Forum (clone)

For puzzle 1, by simple techniques, I arrived at the following state:

Code: Select all

       vvv                    vvv             vvv
+----------------+-----------------+--------------+
| 148  589  1578 | 1478  6    147  | 2    49  3   |
| 14   6    3    | 124   124  9    | 5    8   7   |
| 2    89   78   | 5     478  3    | 14   6   19  |
+----------------+-----------------+--------------+
| 6   +25   245  | 247   3   +2457 | 9    1   8   | xxx
| 9    3    1458 | 148   148  145  | 7    2   6   |
| 18   7    128  | 128   9    6    | 3    5   4   |
+----------------+-----------------+--------------+
| 7    1    269  | 3     24   8    | 46   49  5   |
| 5    4    29   | 6     127 +127  | 8    3  +129 | xxx
| 3   +28   268  | 9     5   +124  | 146  7  +12  | xxx
+----------------+-----------------+--------------+


I marked the swordfish with + signs.

"vvv" marks the columns which are bare of candidate "2" except withing the swordfish pattern.

"xxx" marks the rows where you therefore can eliminate every "2" that is not in the swordfish columns (vvv).

Mac

thx for the nice explanation - now I got it

sweetbix wrote:You have marked the swordfish in 4 columns instead of 3 and so the eliminations aren't quite right.

Sorry about that. I fixed the mistake in the original post.

tso wrote:I fixed the mistake in the original post.

It's not quite right yet.

ronk wrote:

tso wrote:I fixed the mistake in the original post.

It's not quite right yet.

Yikes! That's embarassing. I keep fixing it and forgetting to cut before I paste. I think it's correct now.

I really appreciate your efforts to explain swordfish. I still have difficulty finding them (can they be there if there are more than 2 possible numbers for rx,cx location?).

Now, to tackle xy-wings !!!!

Sheila