The New Sudoku Players' Forum

[Tiramisuu2]

It has taken me far to long to get to these.
I consistently get stuck trying to recognize the fish.

Does anyone have any url recommendation , practice tips, or general clues about how to think about them.

Thanks
T.

[zealot17]

Hi

UFG (ultimate fish guide) and this page explains what fish is.

But I will tell you the basic concept of it. Basicly you need to find bases houses of a digit and cover houses that covers all the base candidates. If a candidate is a member of cover house but not a member of base candidate, then it can be eliminated.

Code: Select all

 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .
---------+----------+----------
 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .
---------+----------+----------
 .  /  . |  .  /  . |  .  /  .
 *  X  * |  *  X  * |  *  X  *
 .  /  . |  .  /  . |  .  /  .

Look at this example. Cells that are marked with "/" don't contain X. " * " represents eliminations. This is a swordfish. Base houses are column 2,5,8. This candidates can also be covered row 2,5,8. These rows called cover houses. Since we have equal number of base and cover houses, any candidate which is a member of cover house and not a base candidate can be eliminated.

Zealot