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Tough Sudoku for 22/January/2011

                 
                 
                 
                 
                 
                 
                 
                 
                 

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Submitted by: Gath

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22/Jan/11 12:09 AM
My first thought, too, Shiela. Great catch, Anne!
22/Jan/11 12:32 AM
1. Unique possibilities to 24.
2. If d6=2,d9=7,locked 8s at f789,f4=1;row 9 is devoid of 1.So f4=2.UP38.
3. If d6=7=a7;row 9 is devoid of 7.So d9=7.UP81.
22/Jan/11 12:44 AM

SE=7.1
22/Jan/11 12:53 AM
Are you certain that he wasn't doing them WHILE driving? Yikes!
22/Jan/11 1:33 AM
similar to Alfred's:
1. SST to UP=24
2. (2)f4=(1368)f4789-(36=HP(57))e78-(7)d9=d6 => d6<>2
UP=39
3. turbot (7)b9=d9-d6=b6 => b4<>7
UP=81

more complicated, but single chain coupling 7s, 9s, and 1s:
2. (7)d9=d6-a6=b4-bd9=(7-9)h9=g7-g456=h5-e5=(1348)def5e-(1)b5=(1-7)b4=a6 => d6<>7
UP=81
22/Jan/11 2:23 AM
I should have shortened that last chain, eliminating the segment g7-g456:
2. (7)d9=d6-a6=b4-bd9=(7-9)h9=h5-e5=(1348)def5e-(1)b5=(1-7)b4=a6 => d6<>7
UP=81
22/Jan/11 2:55 AM
Apologies for typo: def5e should be def5e6.
corrected:
2. (7)d9=d6-a6=b4-bd9=(7-9)h9=h5-e5=(1348)def5e6-(1)b5=(1-7)b4=a6 => d6<>7
UP=81
22/Jan/11 3:34 AM
Hi kobold,
I'm not sure but I feel that I know you by your style...
I think that you’re one of the best player here (like Steve, rwm, Dave and one you know: farpointer – what a sad...), your talent can hepl many players here to improve their skills on solving tough puzzles. So, I hope you live here forever...
22/Jan/11 3:34 AM
as has been pointed out, a complex chain can sometimes be represented more simply as a kraken; grouping is more efficient, and can eliminate dynamic aspects, too:
2. kraken row (7)bdh9 => d6<>7 ; UP=81
(7)b9-b4=a6
||
(7)d9
||
(7-9)h9=h5-e5=(9-7)h9=h5-e5=(HP(79)-1)be4=(1-2)f4=d6
22/Jan/11 5:48 AM
typo in pasting; my apologies; corrected:
2. kraken row (7)bdh9 => d6<>7 ; UP=81
(7)b9-b4=a6
||
(7)d9
||
(7-9)h9=h5-e5=(HP(79)-1)be4=(1-2)f4=d6
22/Jan/11 5:50 AM
(1)f9=(178')d569-(2)d6=f4 > -1f4
FXW(7)be49 > -7e78, UP81

Greetings ttt. hmmm...farpointer? satire amusing to some but clearly not all (no relation).
22/Jan/11 6:12 AM
This is a dangerous game !
22/Jan/11 9:07 AM
Jiminoregon, found a good XYW link in June 22,2010 SE=8.3

1.SSTS to UP40
2.(8=245)ade4-(2)e6=XYW(578)e6d4i6 > -8f6, UP47
3.(5)i1=g2-g7=b7-(245=9)b126-(9=345)a456 > -5ab1 -4a1, UP81
22/Jan/11 9:44 AM
maybe better to abbrev. as YW(abc)pivot|x|y:
(2)e6=YW(578)ei6d4
22/Jan/11 9:55 AM
Hi Jim. I posted a long chained solution for 26 Jan 2009, and made some comments on your impressive proof. You even found a rare 4 possibility kraken there.
How do you spot all these krakens ? Is there a pattern you look for, or is it a hard, trial and error slog ?
Regards, Alfred.
22/Jan/11 10:24 AM
kobold, yes good example. Forgive my errant expressions here. I am trying to articulate my ideas with concrete examples. Some more successful than others.
22/Jan/11 11:10 AM
Alfred, thanks for spotting the errors on my solution for 26 Jan 09. You are correct on all counts. You are a good proof editor.
22/Jan/11 11:16 AM
Alfred, as far as krakens go, I guess it is a matter of practice more than anything else. I also have been reading a lot of commentary here and on the UK sudoku forum. There are several good solvers who post regularly to the UK site. That has helped a lot. I think you can see my solving methods More...
22/Jan/11 11:45 AM
Re: archeaology. When I look back at my early efforts (22 Jun '10), I cannot understand what I wrote, not just because it was confused, but primarily because it wasn't written in eureka.
22/Jan/11 11:54 AM
June 11,2010 SE=8.5 is challenging. had to use a quantum link (garden variety) and then a looped kraken to get over the hump (noticed even farpointer was stumped by this one back in the day).
22/Jan/11 2:05 PM
Hi Jiminoregon (and all),

I think you have (indirectly) said in your 11:54AM post, a really key piece of information -

- Eureka is to communicate the solver's thinking (aka, solution/proof) to other people (and maybe to themselves as well).
22/Jan/11 10:58 PM
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