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Tough Sudoku for 29/December/2010

                 
                 
                 
                 
                 
                 
                 
                 
                 

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Submitted by: Gath

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Looks like snow! Is Bev flying over the East Coast!!!
29/Dec/10 12:10 AM

SE=8.4
29/Dec/10 12:16 AM
So fluffy!
29/Dec/10 1:40 AM
1.SST to UP=26
2.(9=8)e1-e3=(28')ai3-(9)i3=(9-1)i4=i7-e7=(146')e589 => e59<>89, UP=29
3.(4)e9=(4-6)e8=e5-(689)f469=(135)bfh9 => e9<>15, STE.
29/Dec/10 3:11 AM
I think that Bev has had a fleeting glimpse of Heaven!
29/Dec/10 3:11 AM
note: the AIC chain use a new kind of bool link (for me) which I will tentatively call a 'pivot als link'. Here the link is (689)f469==(135)bfh9 and the pivot cell is f9 partitioned on the disjunction of the two sets - a neat way to include a'Sue de coq' in an AIC chain.
29/Dec/10 3:15 AM
note: I erred yesterday when I assumed Alfred was bragging to deaf ears, Neil is in the room. What I'm really saying is that you can't compare the two methods - apples and potatoes, AIC chainers ski down the slopes, UP-chainers take the T-bar.
29/Dec/10 3:24 AM

farpointer:Just posted an alternative for tough Jun 23,2007,4 chains w/o kraken.
29/Dec/10 3:37 AM
sotir: that's a very fine path for Jun-23-07. I knew mine was clumsy (got bogged down in the false assumption that puzzle needed extensive weeding to reach home, when all that was really required was a clear orbit for the digit 8). My only edit is a short coloring chain on 8 for the final step:
5.(8)i7=d7-d2=h2 => i1,h8<>8; STE.
29/Dec/10 4:16 AM
I recognize that place!
29/Dec/10 4:53 AM
Thank you Kathy from Valrico Florida for going to my page and wishing me a happy 52nd wedding anniversary and to all of you who did on the sudoku page. Had a very nice evening. Hon wants to go out again for New Year's Eve. "If I'd have known I was going to live this long I would have taken better care of myself." Who said that? Mark Twain?
29/Dec/10 5:04 AM
-Jack Benny when he finally celebrated his fortieth birthday.
29/Dec/10 5:39 AM
This solution is similar to farpointer's, but directly exploits HP(89)e13 and HT(146)e589.
1. SST to UP=26
2. (1)i7=(1-9)i4=i3-(9=5)g3-e3=(89)e13-(89=136)d128 => e7<>1
UP=29 (NOTE: e7<>1 produces HT(146)e589)
3. (4=135)beh9-(135=89)df9-(89=5)e7-(5=89)e13-(89=136)d128 => e9<>1
UP=81
29/Dec/10 7:01 AM
1.Note pairs 47 at i89;36 at bc3,28 at h5/i6..Unique possibilities to 26.
2. Whether i4=9,f4=6=e8,e9=4,i7=1;OR i3=9,e3=8,f2=5,f1=2,d8=1;d2=6 and e5=1.UP81.(Note triple 135 at adf8).
29/Dec/10 7:43 AM
-depth 20+ forcing chain
29/Dec/10 8:32 AM
-every sudoku puzzle can swiftly be resolved by a guess (perhaps two) followed by a depth 20+ (perhaps two) forcing chain to see if the guess is wrong, this process requires no skill and might better be left to automation.
29/Dec/10 8:43 AM

1)Start at 22,SSTS to UP=26
2)(6=9)f4-i4=i3-(9=5)g3-e3=(5)f2,=>f2<>6.UP=27
3)(1)e5=d46-(1=3)d8-(3=895)d1e13-(5= 9)g3-i3=i4-(9=6)f4,=>e5<>6.UP=32
4)(1=5)i7-e7=e3-(5=9)g3-i3=(9)i4,=>i4<>1.UP=81
29/Dec/10 8:55 AM
addendum: the process described above does not in any way use, or notice, the characteristics peculiar to a puzzle that makes it unique and interesting (except by accident).
29/Dec/10 8:57 AM
Just my $0.02. The words "if" and "then" do not appear at all in a eureka-based proof. Each statement is precise. Each statement is actually a theorem about the puzzle in question, with the advantage that one may also exploit the parity in exactly the manner used by farpointer More...
29/Dec/10 9:50 AM
Farpointer, I'm going to take exception with your characterisation of those using chains (whether 20+ or not), rather than what you believe to be a more pure form of solving tough sudokus, as possessing no skill. A number of your (or Sotir's, Alfred's or Jim's) solutions start out with an More...
29/Dec/10 11:17 AM
I'll get down off my soapbox now!
29/Dec/10 11:18 AM
...and a grammatical correction farpointer - I was taking exception *to* you characterisation, not *with*.
29/Dec/10 11:22 AM
over 1 hour
29/Dec/10 12:03 PM
Jim; the dreaded "if" word doesn't appear in my solution today. It's like a kraken, only there are two possibilities,instead of three, which lead to the same conclusion.
farpointer; each of my chains are 4 or 5 deep.
29/Dec/10 12:09 PM

I agree with farpointer and Jiminoregon .This problem is not new.
Eureka rules does not allow posting proofs using "if" and "then",forcing chains.
But our site has not such rules,so everyone can post proofs in own way.
IMO, the beauty and satisfaction is finding the shortest way, using Eureka Notation.
29/Dec/10 12:12 PM
I am totally in favor of short and simple!
29/Dec/10 12:25 PM
Ditto
29/Dec/10 12:35 PM
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