The New Sudoku Players' Forum

[Hunty]

Hi there, this looks like an amazing forum.

I am still learning and thought the swordfish technique was incredibly useful, but I find it wont work under some circumstances but I am struggling to find out which circumstances.

For example, please take a look below:


According to my swordfish, cell C4 solves as 6 when correct solution is 3, and F8 solves for 4 when it should be a 6.

Can somebody explain my rookie error please ?

[Mauriès Robert]

Hi Hunty,
Your mistake is that there is no swordfish of the 6 on this puzzle. What is your definition of a swordfish?
A simple resolution can be done with an ALS-XZ, like this:
(6=3)r3c4 - (3=6)r1c24 => -6 r1c6 and end with the basics.
or written otherwise (TDP method)
(-6r3c4)->3r3c4->46r1c24->... => -6r1c6 and end with the basics.
Robert

[AnotherLife]

Hi Hunty,
Let me just note that Mauriès Robert's solution is easier to understand as an XYZ-Wing, and this is a standard pattern of just three cells. In this case, they are r1c2, r1c4, and r3c4. Good luck!