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Submitted by: Gath

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I'll have to take your word for it, fi, I'm afraid that I can't see the birds unless those two little spots are their eyes.
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Sorry, I can't see the birds. The cat - yes; but no birds.
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there is a sea lion just ready to break the surface
maen all
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I don't get it. I went through this puzzle the first time and solved it no trouble. When I go the 'Solve Easy' route, I'm stumped.
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Good morning to all! I can't see any birds either. Are they black birds?? Did they migrate for the winter?? Do I need new bi-focals???
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15:32 after setup. I can't see any birds. Do see the rocks though, so all is not lost...
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rocky mystics!
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First tough I've gotten easily in awhile!
Good day to all.
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5:26 after setup. White rocks usually mean birds are close!!
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Possible proof of tough sudoku of 09 18 06:

1) Start at 22 filled - the given puzzle. Unique Possibilities to 27 filled. (UP 27).
2) Pair 28 at d23 forbids d479,e2f3=2 and forbids d7e2=8 UP 30
3) h6=8 == b6=8 -- b6=4 == d6=4 -- d4=4 == d4=3 -- e6=3 == e6=6 forbids h6=6 UP 31
4) More...
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Step 4 in my proof is not very transparent - it is a Hidden Sue de Cox similar step:

If we chunk it with the previous step, it can be shortened to:

e5=3 == e5=25 -- {Hidden pair 25 at ef4} == b4=25 -- b4=8 == d4=3
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One further note of interest:
if one eliminates step 3, one can still do step 4:
{de5=pair 36} == e5=25 -- {Hidden pair 25 at ef4} == b4=25 -- b4=8 == b6=8 -- b6=4 == d6=4 -- d4=4 == d4=3 forbids b4=149, b6=19,and forbids e4f6=3 UP 37
The rest of the steps listed will still work - just up one less until the last step.
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It's taking me ages, but I am finally getting them without guessing!

I thought the picture was meat on the BBQ!
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One final note of interest:
A very nice proof is also available using the almost hidden pair 89 at b46:
{Almost hidden pair 89 at b46}-- {b4=25} == {hidden pair 25 at ef4} -- f4=1 == f6=1 -- f6=7 == d6=7 -- d4=4 -- {Almost hidden pair 89 at b46}
forbids b46=9, plus perhaps some other items....
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1) Start 22, Unique Possibilities to (UP) 27.
2) Naked pair 28 at d23 forbids e2=28, f3=2, d4=2, d7=28, d9=2. UP 30.
3) e2=9 == a2=9 -- a6=9 == ac6=13 -- f6=1 == f6=7 -- f78=27 == f8=9 forbids f3=9. UP 35.
4) d4=4 == d4=3 -- d9=3 == e9=3 -- e9=2 == f7=2 -- i7=2 == i7=4 forbids i4=4.
5) Locked 4s at gi5 forbid b5=4.
6) Hidden pair 48 at b46 forbids b4=125, b6=19. UP 81.
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Excuse my ignorance Steve, but does 'chunk it' mean 'add it'??
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In this case, Kaz - it only meant to use parts of the previous fc. 'chunk' is sort of gereric for using information we already have.
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Very nice proof, Clark!
- much better then mine today. Sometimes I get hung up trying to use techniques beyond what the puzzle actually requires. Your step 3 is much, much more straightfoward then any part of my proof. Guess I should put away my elephant guns until the big game appears.
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This rock looks beautiful. Is that a river at the bottom? It would be nice to go and visit. I would like to see it first hand. Nice picture. Thanks
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I can only see one bird, a cormorant in the middle of the pic on the 'white rock' - like you say Dwain white rocks = birds!
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I see the bird on the white rock, but is that another almost to the top on the 'pink' rock directly above that?
I know I see all kinds of things, but if you look at the center top, it looks like a face in the rock.
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it can be done without resorting to ALS or AHS or even grouped
premises - just 3 simple chains:

1) Start with 22, UP 27
2) NakedPair: d32=28 => ~d974=2, ~(f3, e2)=2, UP 30
3) Locked: bc9=5 => ~h9=5
4) Locked: de9=3 => ~hi9=3
5) Locked: def6=7 => ~h6=7
6) e9=3 More...
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in the above Clark gets credit - I would have skipped looking at the seemingly ineffectual
steps 7 and 8.
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I had to remove a possibility by trying, until an impossibility arised. Then in a triplet consisting of 3 pairs the first(out of two possibilities)chosen lead straight to the solution!
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Very well done, Pat!

Again, I apologize to all proof readers for forcing in a technique that a puzzle did not even come close to requiring - kinda like having a new toy - just want to use it somewhere!
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Cyndi,glad it wasen't just me,I also saw the beak at the right as an image of a bird with a squinted eye to the left above that beak image.Now I see the bird on the white rock also.Takes a bit of study.Good picture!
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Finding the birds was harder than doing the puzzle.
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i dont follow clarks proof. In step 3, a3=9 is also a possibility, how is it eliminated?
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nevermind
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The whole image looks like a bird to me - especially coming in. The cavern is the beak tucked into the bird's breast - a glistening eye at the top. The brown neck and paler body feathers.
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ah!birds where??nevermind..if fi says it must be there..i think so for she is the one who took the pic..
cheers
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It took a while... 46 mins to do the puzzle... but at least I spotted the bird straight away. I even see Kate's bird... sort of like a pelican I reacon!
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I am new to this so just had to ask if at any point you have to guess or is there always a logical next step?
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Over an hour to solve.
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19:24.
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27:33 new to sudoku, nice way to keep mind limber
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Nov. 23, 2007.
24/Nov/07 3:35 PM
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SE=7.2
05/Sep/10 10:01 PM
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