## Did I catch a 500 pound swordfish?

Post the puzzle or solving technique that's causing you trouble and someone will help

### Did I catch a 500 pound swordfish?

This suduko is from http://www.sudokusolver.co.uk/grids_veryhard.html
It is the #3 sudoku, Difficulty score of 916

I missed a Hiddden Pair of '6' and '9' in the location R7C4 & R7C6...BUT I am wondering
if my find on the swordfish is correct or not.

I filter for 7's and they were all green.
Then I made the pairs orange
Then I think I can eliminate the purple.

Correct?

Thanks,

LTP
lovethepirk

Posts: 8
Joined: 22 February 2006

Please use text grids whenever possible. Those of us that are colorblind have no idea which cells you are refering to as being green, orange or purple. (I don't know why Simple Sudoku and some others Sudoku aps insist on using pastel colors that are nearly indistinguishable to 150 to 300 million people worldwide.) Most readers prefer to be able to copy the text into whatever app they might use. Since you are already using SS, just copy and paste.

Code: Select all
` *-----------* |1..|...|.8.| |.9.|7.2|..5| |...|...|...| |---+---+---| |.5.|.6.|..2| |8..|.9.|.1.| |.3.|.4.|..7| |---+---+---| |...|...|...| |.7.|3.5|..4| |6..|...|.9.| *-----------*`

Code: Select all
`*--------------------------------------------------------------------------------------* | 1        246      234567   | 469      35       469      | 23467    8        369      | | 34       9        3468     | 7        138      2        | 1346     346      5        | | 3457     2468     2345678  | 14689    358      14689    | 23467    23467    1369     | |----------------------------+----------------------------+----------------------------| | 47       5        19       | 18       6        37       | 89       34       2        | | 8        246      2467     | 25       9        37       | 3456     1        36       | | 29       3        1269     | 25       4        18       | 89       56       7        | |----------------------------+----------------------------+----------------------------| | 345      1248     23458    | 14689    278      14689    | 2357     2357     138      | | 29       7        289      | 3        128      5        | 126      26       4        | | 6        1248     23458    | 148      278      148      | 2357     9        138      | *--------------------------------------------------------------------------------------*`

There is no swordfish in sevens from this position.

Code: Select all
` *---------------------------------------------* | .    .    7  | .    .    .   | 7    .    .  | | .    .    .  | 7    .    .   | .    .    .  | | 7    .    7  | .    .    .   | 7    7    .  | |--------------+---------------+--------------| | 7    .    .  | .    .    7   | .    .    .  | | .    .    7  | .    .    7   | .    .    .  | | .    .    .  | .    .    .   | .    .    7  | |--------------+---------------+--------------| | .    .    .  | .    7    .   | 7    7    .  | | .    7    .  | .    .    .   | .    .    .  | | .    .    .  | .    7    .   | 7    .    .  | *---------------------------------------------*`

A Swordfish will be 6 to 9 cells that sit in exactly THREE rows and THREE columns.

I don't know what you mean by "Then I made the pairs orange". There are no pairs in a Swordfish.

I'm guessing that by "purple", you mean r3c3, r3c7 and r7c7. No, you cannot exclude these. In fact, r3c3 is actually a 7 in the solution.
tso

Posts: 798
Joined: 22 June 2005

tso wrote:Please use text grids whenever possible. Those of us that are colorblind have no idea which cells you are refering to as being green, orange or purple. [i](I don't know why Simple Sudoku and some others Sudoku aps insist on using pastel colors that are nearly indistinguishable to 150 to 300 million people worldwide.)

Simple Sudoku allows the user to customize the colors. Perhaps you could advise us which colors would be much better.

TIA, Ron
ronk
2012 Supporter

Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

I'm not much of a swordfisher, but it's my understanding that if the only rows containing 2 or 3, 7s were rows 1,4,5, the swordfish would be legit. The 2 or 3, 7s in rows 7 and 9 make it illegitimate. Hope I got it right.
Hud

Posts: 570
Joined: 29 October 2005

Hud,

The selected cells in rows 1, 4, 5 align in four columns, so it can't be a swordfish.

Tracy
TKiel

Posts: 209
Joined: 05 January 2006

tso,

I will use grids from on now, I appologize. I am a newbie

Thanks for the feedback everyone else.

i still am VERY confused on Swordfish, but I am going to tutorial it and study it on my own today and I will post back here with any specific questions.

Regards,

LTP
lovethepirk

Posts: 8
Joined: 22 February 2006

The selected cells in rows 1, 4, 5 align in four columns, so it can't be a swordfish.

Thanks Tracy, I missed that one. At first glance, I thought they were in 3 columns but not so.
Hud

Posts: 570
Joined: 29 October 2005

ronk wrote:Perhaps you could advise us which colors would be much better.

A good choice is to start with the three primary colors -- blue, yellow and red. I didn't put much thought to the other colors other than making them distinguishable from the primary colors and each other.

Good choices are strong, pure colors. Light and dark shades help as well. A light and a dark red, a light and a dark blue, a deep and a pale yellow. Reds or browns may be indistinguishable from greens of the same intensity.

These are the settings I currently use in Simple Sudoku. Remember, there are different types of color weakness, so don't blindly follow me. (yuk)

General colors:

Code: Select all
`                 RED, GREEN,  BLUEDark             176,   196,   215Pale             241,   242,   245Filtered         255,   255,   128Selected         255,   255,   128`

Marker colors:

Code: Select all
`"Blue"             0,     0,   255  "Green"          255,     0,     0"Pink"           255,   255,     0"Amber"          128,    64,    64`

Primary blue is a little dark, making the candidates hard to see. Better might be 64, 64, 255.
tso

Posts: 798
Joined: 22 June 2005

tso wrote:
ronk wrote:Perhaps you could advise us which colors would be much better.
These are the settings I currently use in Simple Sudoku. Remember, there are different types of color weakness, so don't blindly follow me. (yuk)

Your response is much more detailed than I was expecting. Thanks.

However, as you pointed out, the candidates *are* very difficult to read on your Blue marker color. I have the same problem with the "Amber". BTW general colors Filtered and Selected are the same. Is that a typo?

Ron
ronk
2012 Supporter

Posts: 4764
Joined: 02 November 2005
Location: Southeastern USA

ronk wrote:...general colors Filtered and Selected are the same. Is that a typo?

No. It just doesn't matter to me. Those two items are never in conflict. When filtering, selected cells are only highlighted by a border. Black (0-0-0) for 'selected' actually works quite will if you prefer. The candidates are quite visible.
tso

Posts: 798
Joined: 22 June 2005