Can the Swordfish strategy be used to solve this puzzle
Please help with daily challenging puzzle for 08/20/2006 ,#380.
Consider the possibilities for 1 in row 4 (columns 1,2,and 3. The possibility of 1 has been eliminated in column 6 of this row.)
Look at the possibilities for 1 in row 7 (columns 1,2, and 7)
Finally look at the possibilities for 1 in row 9 (columns 2, 3, and 7. The possibility for 1 has been eliminated in column 4 of this row.)
My first thought was this pattern formed a Swordfish, but if it does, then all possibilities for 1 are eliminated in row 1,because they appear in columns 1,2, and 3.
This obviousally can't be true, so is the pattern a Swordfish?
I don't think you have s Swordfish there actually. They do seem to be very rare.
When I look for a X Wing or Swordfish I look for arrangements of a possible symbol arranged in a box. The key is seeing two in a row or column. In the X-Wing they form the corners of a box in the Swordfish there are three pairs forming two overlapping boxes. At a quick glance I can't spot the '1' s in your puzzle forming a box there seem to be three possible positions in the rows and columns.
I can't see an easy solution strategy. There are quite a few straightforward squares to solve but it then reaches a stage when nothing can be easily solved. For example 5 must go in Aa as there are no other places a 5 can go in block Aa.
I think I'd need to do a trial and error strategy to solve it.
If you look at a full "Pencilmark matrix" for this puzzle, you will see that there are two cells in row E that are mandated. Cell Ed is a 6 and cell Ef is a 4. With that knowledge, you can easily solve all of Row E.
Following that, other cells are mandated. Chasing down the chains gives you a total of 48 of 81 cells solved.
You now have a 7,6 twin in the top center sector in cells Ae and Be. Place a 6 in cell Ae and the solution just falls out.
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