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Tough Sudoku for 19/September/2006


Choose a number, and place it in the grid above.

  1 2 3 4 5 6 7 8 9
Check out the latest post in the Sudoku Forum

Sudoku Solving Techniques

Submitted by: sudoku lover

Indicate which comments you would like to be able to see

That's better fi, we can see the birds now.
Now I see the bird.
Wild birds! I do like the rock photo from yesterday though!
8:00 Maen
Cream Puff! Max depth 3, hardest required technique is xy wing - albeit one may be able to skip even that.
Pretty easy, but here is my simple proof.
1) start 23 UP 28
2) pairs 58 at c45, 37 at h79
3) locked 3s at d89 forbids d2=3 UP 29
4) triples 237 at d8 d9 e9 and 129 at a2, c2 i2 UP 40
5) pairs 46 at g2 h2, 47 at a6 b6 UP 41
6) locked 5s at d5 f5 forbids c5=5
7) locked 2s at ef3 More...
To Steve: This was easier than some tough ones, but I cannot say it was a cream puff for me!:) I just keep plugging away and thank Gath for the check moves and possibilities options.
Put the binoculars on, and I could see the birds.
It looks like yesterday's picture, but up closer. Interesting.... The rock is beautiful. Thank you.
Is solving Sudoku an art...or a science?
The rock is beautiful? That beauty comes from the guano, not from the rock...
Beauty is in the eyes of the beholder. I enjoy seeing rocks, cliffs, and rivers/lakes. This rock has unique colors. (Grays and reds.) It can tell you about the area.
Easy techniques to 49. UR at a6,a8,b6,b8 elim. ab8=4. UP 81
With apologizes to Fi:

What birds Anne, HalT, Kate and others? All I see are disguised flying cats and a cat bed lying on top of a rock??
Its that cormorant again!
This one was taking me too long, so I quit without finishing. Too much else to do right now.
the inevitable AUR proof:

1) Start with 23, UP 28
2) NakedPair: h97=37 => ~(h32, g8)=7
3) NakedPair: gi8=58 => ~df8=58
6) NakedTriple: aci2=129 => ~dfgh2=12
7) NakedPair: d82=37 => ~d973=37
8) UP 49
9) NakedTriple: cei6=129 => ~ab6=129
10) AUR: (a6, b6, More...
to Bruce: your chain doesn't add up, but is close
to what could be used instead of AUR or XYWing:

e7=8 == e3=8 -- d3=8 == d3=1 -- e1=1 == e1=4
=> ~e7=4, UP 81.
Possible solution for tough of 9/17/06

1. Start at 23, a1=5 via UP 24
2. locked 58 at c45, eliminate in col
3. c9=6 via UP 25
4. Locked 2's at abc7 forbid def7=2
5. pair 58 at gi8 eliminate in row
6. Locked 37 at h79 eliminate in col
7. g6=3 via UP 26
8. i9=4 via UP More...
Is there a reference to interpret your comments. For example, where is 'd8'? The comments are almost as difficult to solve as the puzzle.
Oops, missed a step above. Turns out the fc is not needed. Same as before but I didn't see the last locked 1's.

Possible solution for tough of 9/17/06

1. Start at 23, a1=5 via UP 24
2. locked 58 at c45, eliminate in col
3. c9=6 via UP 25
4. Locked 2's at abc7 forbid More...
the best reference is to follow the proofs link below and read the tough comments going backwards from today.

The rows are number 1-9 starting at the bottom.
The cols are labeled a-i, starting on the left.
So d8=6 means set the cell at the 4th col from the left, 8 rows up to 6.
33:26 with a lot of distractions. At least today I can see the birds! Not so sure about the nest though.
12:21 getting better,
4.21.......using elflasho method gets best results
Pretty precarious if the egg rolls!
done..not so tough and took just abt 10 t0 15 mintes to see the birds,,yes they are visible today and i dont see the nest or whatever look like a nest..and lizbaby does seem to have a point abt the rolling eggs..
easier than most previous
very good~~~
Nov. 23, 2007.
24/Nov/07 3:55 PM

05/Sep/10 10:01 PM
12/Jan/20 3:55 PM
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