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Tough Sudoku for 22/May/2014

                 
                 
                 
                 
                 
                 
                 
                 
                 

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

Sudoku Solving Techniques

Submitted by: sudoku lover

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everybody!

22/May/14 12:01 AM
SE=7.2 UP to 28
1)2-chain logic:(3)e2=(6)f1=(8)g1,(3)f1 or (3)i2=(7)i1=(36)cf1=(8)g1 => g1=8,i3<>7 UP=40
2)H-Wing:(4-5)i1-a1=(4=5)a9=(5)i9 => i1<>5 UP=81
22/May/14 12:47 AM
Wonder if they got tummy ache
22/May/14 2:15 AM
I wonder who took the bite?
22/May/14 2:26 AM
SSTS
1)(4)d1=d6-(4=3)e6-e2=(3-7)i2=(7)i1,=>i1<>4
2)(4=5)i9-i1=(5-4)d1=(4)a1,=>a9<&G T;4.UP=81
22/May/14 2:46 AM
(27) 45@ai9=>a9<>8
(29) 3@c13=>a2<>3
5?@i1=>[a9=5=>a4=9&i2=7=>e2=3=>f1=6=>f3=2]=>f4={}=& GT;i1<>5
(33) 7@f56=>e6<>7
VHBC to (81)
V:Only cell left in Vertical column for this More...
22/May/14 6:36 AM
Like Les's:
1. Unique possibilities to 28.
2. Whether f4=9,a4=5=i9;OR f431=263,i2=3,i1=7;d1=5.UP81.
22/May/14 7:25 AM
some puzzles which code does poorly on and 'pattern aware' humans may find efficient paths
22/May/14 7:37 AM
X-6 *: Symmetry=None, Start=25, SSTS=28, SG=21.75, SE =9.0 (try this one Alfred)
601070008000000000457000020000400290930000004008060075000000009004006050800210000
22/May/14 7:39 AM
X-7: Symmetry=None, Start=25, SSTS=33, SG=19.25, SE =9.0
000109020900036000020040000300050600000064090080000004072000100034007008000010040
22/May/14 7:40 AM
X-8: Symmetry=None, Start=26, SSTS=31, SG =14.75, SE =8.9
090002040000500000000047609028000050500000960906000104000076002010900800007080000
22/May/14 7:41 AM
X-9: Symmetry=None, Start=25, SSTS=33, SG =30.5, SE =85 12 19
002009000030080000500004070000400001000062030000005920945007060060048700300000000
22/May/14 7:42 AM
X-10: Symmetry=None, Start=24, SSTS=28, SG =30.25, SE =9.0
800006007000040008000000690019007000000320000700509000080000700005003004201900005
22/May/14 7:43 AM
X-11: Symmetry=None, Start=24, SSTS=24, SG =18.75, SE =9.0
000040000500000600306000091900051082000008300070400500009002000100080003080000070
22/May/14 7:44 AM
X-12 **: Symmetry=None, Start=23, SSTS=27, SG =19.5, SE =8.5
700030000500000000004080902600005001210000090050000030000406009000200080000100065
22/May/14 7:46 AM
X-13: Symmetry=None, Start=24, SSTS=29, SG =19.75, SE =8.9
200007030008000690000640500000060080706309000090000000000400020007010060320500000
22/May/14 7:47 AM
X-14: Symmetry=None, Start=24, SSTS=30, SG =14.25, SE =9.0
000090000000007062000560000003000000500020004620004007018000490062001003070900000
22/May/14 7:48 AM
X-15: Symmetry=None, Start=25, SSTS=28, SG =16.5, SE =9.0
004050901000000046100090800905704008030100005800500000000000004000000370062040000
22/May/14 7:49 AM
possible path for X-15:

the obscure hit -2a9 weakens the position profoundly; reaching STE.
(oddly SE=8.9 after step 1; one must be 'pattern aware' to find the ste sequence; randomly
taking chains that look good piles up a high point score - SG)
note: revision to AIC cost; depth 2 More...
22/May/14 7:51 AM
possible path for X-13
double kraken KO:
note MW(54')h45 is based on (4)h1=(54')h45 @ MW(54)h4/(4)f46.(5)ab6 - (5)c4
----------------------------------------------------------------------

// HW(82)f7/d82.(9)d9; -8d9

1. DK: (23=4589)abdg2 - (159=48)b3c13 # More...
22/May/14 7:54 AM
possible path for X-11 (a net solver would never dream of softening up the position with the
short sequence of patterns after step 1)
------------------------------------------------------------------------

1. [(4)f2=f1-a1=*(4-7)a3=c2] - (7)f2=f789 - (7=2)e7 -(2=4)b7 & -(2)e45=d5 More...
22/May/14 7:59 AM
Because of many fruitless previous attempts, I have vowed never to try any puzzle over SE 8.5. But I have succumbed to kobold's temptation this time, probably because of the prospect of invoking many Unresolvable Rectangles (URs).
22/May/14 2:49 PM
Puzzle X-6. 1. Unique possibilities to 28.
2. Whether b9=2;OR f9=2=a4;a8=3.UP293.
3. Whether a4=1,a3=2;OR a4=2,b2=9(to avoid 17 UR @ ab26),f1=9;a3<>5.UP45.
4. Whether b2=1;OR b2=9,b1=6;g2=8(to avoid the 68 UR @ gh15).UP56.
5. f7=19 to avoid the 38 UR @ ef67.
6. Whether c1=5,f15=71;OR c1=3=h3,h9=4,g9=9;f7=9.UP81.
22/May/14 2:49 PM
Step 2 should read UP29.
22/May/14 2:52 PM
Also, in step 4, should read ...@ gh35...
22/May/14 6:39 PM
Easy After A9 and a Little later D1 cant be 4
23/May/14 12:37 AM
X-6, SE=9.0
SSTS
1)(2):e8=e5-c5=a4,=>a8<>2
2)AUR(17)ab36:(1)a4=(9)b2-de2=(9-5)f1=c1-(56=2)c65 ,=>a4<>2.=>SE=7.2
23/May/14 1:46 AM
Typo, 2)AUR(17)ab26
23/May/14 1:54 AM
Toad Bites?
23/May/14 4:47 PM
Path to X-7. Unlocked with one kraken.
Standard techniques UP 33
1. Kite (7)a7=d7-e9=e4 =>a4<>7
2. Kraken column (1)h8764 =>SIS 7a7=2a5 =>a5<>7 UP 39
||(1-6)h7=(6-9)i7=i3-(9=8)e3-(8=7)e9-d7=(7)a7
||(1-87)h68=(7)h4-e4=e9-d7=(7)a7
||(1)h4-f4=(1-2 More...
24/May/14 5:33 AM
X-7
Almost as above,one kraken (1357)h4,=>d7<>7
27/May/14 1:01 AM
X-8
First attempt 11 steps (3 kraken).
I tried another path,but I am not sure for step 1 is valid or no. Please kobold let me know your
opinion.

1)XW(1)dh37=(1)a7-(1=4)a6-a2=(4)f2,=>d3<>4
27/May/14 1:19 AM
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