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Tough Sudoku for 13/September/2010


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Submitted by: Gath

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13/Sep/10 12:09 AM
The hills are alive with the sounds of muuuuuussssiiiccccc...
13/Sep/10 12:59 AM
13/Sep/10 1:10 AM

1) Start at 23,SSTS to UP=26
2) (7)f9=(7-8)b9=c7-c1=f1-e23=(8-1)e4=e78-(1=2)d9,=>f9<>2.UP=31
3)(9=5)f3-f8=b8-(5=8)c8-c1=(8 -4)f1=(4)d1,=>df1<>9.UP=81
13/Sep/10 1:53 AM

Sorry,I have to revise my solution.Step 3 is not valid.
13/Sep/10 2:01 AM
1.SST to UP=26 (using complex but shorter chains)
2.(7)f9=e7-(7=268)e236-(8)f1=c1-c7=b9 => b9<>7; UP=31
3.(68=2)e23-XW(2)ei68=df6-f45=HP(24)f16 => f1<>8; UP=81.

couldn't resist that almost XWing link.
13/Sep/10 2:38 AM
13/Sep/10 2:59 AM
you can of course run the chain around the XWing:
2.(68=2)e23-e8=i8-i6=def6-f45=HP(24)f16 => f1<>8.
//the chain length efficiency would be greater if it were an almost swordfish.
13/Sep/10 3:11 AM
1) Start at 23,SSTS to UP=26
2) (7)f9=(7-8)b9=c7-c1=f1-e23=(8-1)e4=e78-(1=2)d9,=>f9<>2.UP=31
3)(5):b8=f8-f3=d2,=>b2< >5
13/Sep/10 3:21 AM
SST to UP=26.
ii)loop: (7)a7=(7-1)e7=(1-8)e4=f45-f1=c1-c7=(8-7)b9=a7
iii)kraken cell (238)f4=>f1<>8
13/Sep/10 3:25 AM
1. Unique possibilities to 26.
2. Whether a8=1;OR a7=1,b9=7,f9=2,d9=1; e8<>1.
3. If c7=8=b2=e4,e7=1;the 18 rectangle at gi39 cannot be resolved. So c7=5.UP81.
13/Sep/10 4:34 AM
I noticed later that my step 2 is not necessary. When 1 is locked at e78 (after e4=8), then, by inspection, the 18 AUR can already be invoked.
13/Sep/10 8:56 AM
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