Timer
00:00:00
Start Pause Reset
12 Comments Previous / NextHelp

Tough Sudoku for 13/September/2010

                 
                 
                 
                 
                 
                 
                 
                 
                 

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

Welcome to the Sudoku Forums!

Submitted by: Gath

Indicate which comments you would like to be able to see


SE=7.3
13/Sep/10 12:09 AM
The hills are alive with the sounds of muuuuuussssiiiccccc...
13/Sep/10 12:59 AM
24:41
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
43:25
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
4)(5=268)d2e23-(8)f1=c1-(8=5)c7,=>d7<>5.UP=81
13/Sep/10 3:21 AM
SST to UP=26.
i)(1)a8=(1-7)a7=(7-9)e7=e8
=>e8<>1
ii)loop: (7)a7=(7-1)e7=(1-8)e4=f45-f1=c1-c7=(8-7)b9=a7
=>e7<>7,cf3<>8
UP=31.
iii)kraken cell (238)f4=>f1<>8
(2)f4-a4=c45-(2=8)c1
||
(3)f4-(3=5)f8-f7=(5-8)c7=c1
||
(8)f4
UP=81.
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
Please Log in to post a comment.

Not a member? Joining is quick and free. As a member you get heaps of benefits.

Join Now Login