The New Sudoku Players' Forum

by **JC Van Hay** » Fri Apr 06, 2012 2:23 pm

"Weekly Unsolveable" AS#49, here - SE10.8

002800000030060007100000040600090000050600009000057060000300100070006008400000020

Solution based on abi's deep understanding of exocets, here.

#1. ALS (124)r46c4

a. There is an exocet at the very start.

Code: Select all: +------------------------+----------------------------+------------------------+ | 579 469 2 | 8 1347 13459 | 3569 1359 1356 | | 589 3 589(4) | 59(124) 6 -59(124) | 589(2) 589(1) 7 | | 1 689 56789 | 2579 237 2359 | 235689 4 2356 | +------------------------+----------------------------+------------------------+ | 6 1248 13478 | (124) 9 12348 | 234578 13578 12345 | | 378(2) 5 378(14) | 6 38(124) 38(124) | 378(24) 378(1) 9 | | 2389 12489 13489 | (124) 5 7 | 2348 6 1234 | +------------------------+----------------------------+------------------------+ | 2589 2689 5689 | 3 2478 24589 | 1 579 456 | | 359(2) 7 359(1) | 59(124) (124) 6 | 359(4) 359 8 | | 4 1689 135689 | 1579 178 1589 | 35679 2 356 | +------------------------+----------------------------+------------------------+ Exocet : base 124[r4c6=r6c4] (SF=Swordfish) 1r46c4-1r28c4.r5c56=SF(1)[r2c6=*r2c8-r5c8=*r5c3-r8c3=*r8c5] || 2r46c4-2r28c4.r5c56=SF(2)[r2c6=*r2c7-r5c7=*r5c1-r8c1=*r8c5] || 4r46c4-4r28c4.r5c56=SF(4)[r2c6=*r2c3-r5c3=*r5c7-r8c7=*r8c5] => SF(1)=SF(2)=SF(4) or => [1r2c6=1r8c5]=[2r2c6=2r8c5]=[4r2c6=4r8c5] or => Target : 124[r2c6=r8c5] => -58r2c6 Conclusion : r2c6 and r8c5 can only contain the digits 1, 2 and 4 => -59r2c6

b. Further analysis of the exocet.

Let us examine the implications of each possible solution of the ALS (124)r46c4 :

Code: Select all: +--------------------------+-------------------------------+--------------------------+ | 579 69(4) 2 | 8 347-1 13459 | 3569 359-1 1356 | | 589 3 589(4) | 59(4-12) 6 -59(12-4) | 589(2) 589(1) 7 | | 1 689 56789 | 579-2 37-2 2359 | 35689-2 4 356(2) | +--------------------------+-------------------------------+--------------------------+ | 6 28(14) 3478-1 | (12-4) 9 348-12 | 34578-2 3578-1 135(24) | | 378(2) 5 378(14) | 6 38(4-12) 38(4-12) | 378(24) 378(1) 9 | | 389-2 289(14) 3489-1 | (12-4) 5 7 | 348-2 6 13(24) | +--------------------------+-------------------------------+--------------------------+ | 589-2 2689 5689 | 3 2478 4589-2 | 1 579 56(4) | | 359(2) 7 359(1) | 59(4-12) (12-4) 6 | 359(4) 359 8 | | 4 689(1) 35689-1 | 579-1 178 589-1 | 35679 2 356 | +--------------------------+-------------------------------+--------------------------+ 12r46c4 || (14r46c4) 14r28c4.r5c56=[1r5c3=1r5c8-1r2c8=(1-4)r2c6=4r2c3] 4r5c56========4r5c3=4r5c7 4r8c4===============4r8c7=4r8c5 1r8c4=====================1r8c5=1r8c3 1r5c56==========================1r5c3=1r5c8 1r2c4=================================1r2c8=1r2c6 4r2c4=======================================4r2c6=4r2c3 DP(14)r46c24====================1r9c2=============4r1c2 || (24r46c4) 24r28c4.r5c56=[2r5c7=2r5c1-2r8c1=(2-4)r8c5=4r8c7] 4r5c56========4r5c7=4r5c3 4r2c4===============4r2c3=4r2c6 2r2c4=====================2r2c6=2r2c7 2r5c4===========================2r5c7=2r5c1 2r8c4=================================2r8c1=2r8c5 4r8v4=======================================4r8c5=4r8c7 DP(24)r46c49====================2r9c7=============4r7c9 Comments : Case 1 : 12r46c4 Case 2 : 14r46c4 1r5c3=1r5c8-1r2c8=(1-4)r2c6=4r2c3 => -4r5c3, +4r5c7 => +4r8c5, +1r8c3 (=> -1r9c2), +1r5c8, +1r2c6, +4r2c3 (=> -4r1c2) IOW, SF(1) and SF(4) are solved, r46c2=14 => DP(14)r46c24 ! Case 3 : 24r46c4 2r5c7=2r5c1-2r8c1=(2-4)r8c5=4r8c7 => -4r5c7, +4r5c3 => +4r2c6, +2r2c7 (=> -2r3c9), +2r5c1, +2r8c5, +4r8c7 (=> -4r7c9) IOW, SF(2) and SF(4) are solved, r46c9=24 => DP(24)r46c49 ! Conclusions : +NP(12)r46c4 => -12r2389c3.r45c56 SF(1) => -1r1c5.r9c4 SF(2) => -2r3c5.r7c6 Furtermore, SF(1) and SF(2) enter into the following nice loop : {(1-2)r2c6=2r2c7-2r5c7=2r5c1-2r8c1=(2-1)r8c5=1r8c3-1r5c3=1r5c8-1r2c8} => -459r2c6, -2r346c7, -2r67c1, -4r8c5, -1r469c3, -1r14c8

Note 1 : the puzzle is reduced to SE9.0.

Note 2 : AS#49 seems to be a clone of Fata Morgana. To wit the corresponding situation :

Fata Morgana : 000000003001005600090040070000009050700050008050402000080020090003500100600000000

#2.

Code: Select all: +----------------------+------------------------+-------------------------+ | 59(7) 469 2 | 8 3-7(4) 359(14) | 3569 359 356(1) | | 589 3 4589 | 59(4) 6 (12) | 589(2) 59(18) 7 | | 1 689 56789 | 579 37 2359 | 35689 4 2356 | +----------------------+------------------------+-------------------------+ | 6 1248 3478 | 12 9 348 | 34578 357(8) 12345 | | 8(237) 5 13478 | 6 348 348 | 3478(2) 137(8) 9 | | 89(3) 12489 3489 | 12 5 7 | (348) 6 1234 | +----------------------+------------------------+-------------------------+ | 589 2689 5689 | 3 2478 4589 | 1 579 456 | | 59(23) 7 1359 | 59(4) 12 6 | 359(4) 359 8 | | 4 1689 35689 | 579 178 589 | 35679 2 356 | +----------------------+------------------------+-------------------------+ 7r1c1=7r5c1 2r5c1=2r8c1 3r5c1=3r8c1=3r6c1 2r5c1=============2r5c7 2r2c7=2r2c6 1r2c6=1r1c6 1r1c9=1r2c8 8r2c8=8r45c8 3r6c7=========================8r6c7==4r6c7 4r8c7=4r8c4 4r1c5===============================4r1c6====================4r2c4 => 7r1c1=4r1c5 => -7r1c5

#3.

Code: Select all: +----------------------+--------------------+-------------------------+ | 7 469 2 | 8 34 13459 | 3569 359 1356 | | 589 3 4589 | 459 6 (12) | 589(2) 589-1 7 | | 1 689 5689 | 579 37 2359 | 35689 4 2356 | +----------------------+--------------------+-------------------------+ | 6 1248 348(7) | 12 9 348 | 3458(7) 3578 12345 | | 238 5 348(17) | 6 348 348 | 348(27) 38-7(1) 9 | | 389 12489 3489 | 12 5 7 | 348 6 1234 | +----------------------+--------------------+-------------------------+ | 589 2689 5689 | 3 48(27) 4589 | 1 59(7) 456 | | 2359 7 359(1) | 459 (12) 6 | 3459 359 8 | | 4 1689 35689 | 579 178 589 | 3569(7) 2 356 | +----------------------+--------------------+-------------------------+ 1r5c8=1r5c3 7r5c3=7r4c3 1r8c3=======1r8c5 2r8c5=2r7c5 7r7c5=7r7c8 7r4c7=============7r9c7=7r5c7* 2r5c7=2r2c7 1r2c6=====================================2r2c6 => *1r5c8=7r5c7 : -7r5c8; 1r5c8=1r2c6 : -1r2c8; 10 Singles

#4.

Code: Select all: +---------------------+----------------------+----------------------+ | 7 69(4) 2 | 8 (34) 3459 | 3569 359 1 | | 589 3 89(45) | 59(4) 6 1 | 2 589 7 | | 1 689 689(5) | 59(7) -3(7) 2 | 35689 4 (356) | +---------------------+----------------------+----------------------+ | 6 148 3478 | 12 9 348 | 34578 3578 2345 | | 2 5 3478 | 6 348 348 | 3478 1 9 | | 389 1489 3489 | 12 5 7 | 348 6 234 | +---------------------+----------------------+----------------------+ | 589 2 89(56) | 3 78(4) 589(4) | 1 579 5(46) | | 359 7 1 | 59(4) 2 6 | 3459 359 8 | | 4 89(6) 89(356) | 59(7) 1 589 | 59(367) 2 5(36) | +---------------------+----------------------+----------------------+ 3r1c5=4r1c5 4r1c2=4r2c3 4r2c4=======4r8c4 4r7c56=4r7c9 7r3c5==========================7r3c4 7r9c4=7r9c7 6r7c9=======6r9c7=6r9c9 6r9c23=6r7c3 3r9c7=3r9c9========3r9c4 5r2c3=================================5r7c3=5r9c4=5r3c4 3r3c9======================================6r3c9==============5r3c9 => 3r1c5=7r3c5=3r3c9 => -3r3c5; 3 Singles, Claiming(+3r3c79) => -3r1c78

#5. Skyscraper(3C18) : 3r6c1=3r8c1-3r8c8=3r4c8 => -3r4c3.r6c79

#6.

Code: Select all: +---------------------+------------------+-------------------+ | 7 69(4) 2 | 8 34 3459 | 569 59 1 | | 589 3 589(4) | 59(4) 6 1 | 2 589 7 | | 1 689 5689 | 59 7 2 | 35689 4 356 | +---------------------+------------------+-------------------+ | 6 8(14) 478 | 12 9 348 | 34578 358 2345 | | 2 5 478 | 6 348 348 | 3478 1 9 | | 389 89(14) 3489 | (12) 5 7 | 8-4 6 (24) | +---------------------+------------------+-------------------+ | 589 2 5689 | 3 48 4589 | 1 7 456 | | 359 7 1 | 59(4) 2 6 | 359(4) 359 8 | | 4 689 35689 | 7 1 589 | 3569 2 356 | +---------------------+------------------+-------------------+ (4=2)r6c9-(2=1)r6c4-1r6c2=(1-4)r4c2=[4r6c2=]4r1c2-4r2c3=4r2c4-4r8c4=4r8c7 => 4r6c9=4r6c2=4r8c7 => -4r6c7; 11 Singles

#7. Skyscraper(9C48) : 9r3c4=9r8c4-9r8c8=9r1c8 => -9r1c6.r3c7; stte

by **ronk** » Fri Apr 06, 2012 4:11 pm

JC Van Hay wrote:Note 2 : AS#49 seems to be a clone of Fata Morgana.

This Andrew Stuart Weekly Extreme Unsolvable #49 is definitely an isomorph of tarek's Fata Morgana.

by **daj95376** » Fri Apr 06, 2012 4:49 pm

ronk wrote:AS#49 is a morph of tarek's Fata Morgana.

Are morphs allowed to contain extra clues/givens?

Code: Select all: 020400000400009200098000004000600007500010000040003800300000060000700001004008500 AS#49 020400000000009200098000004000600007500010000040003800300000060000700001004008500 FM

by **tarek** » Fri Apr 06, 2012 5:09 pm

daj95376 wrote:
ronk wrote:AS#49 is a morph of tarek's Fata Morgana.

Are morphs allowed to contain extra clues/givens?

Code: Select all
020400000400009200098000004000600007500010000040003800300000060000700001004008500 AS#49 020400000000009200098000004000600007500010000040003800300000060000700001004008500 FM

I can always claim that it is a Prtially solved FM :twisted:

by **ronk** » Fri Apr 06, 2012 5:54 pm

daj95376 wrote:Are morphs allowed to contain extra clues/givens?

No, not normally. but Fata Morgana has been posted many times with hidden single r5c5=5 already placed. Earliest instance AFAIK is here circa Sep 2008.

This scenario points out the importance of a library of hardest puzzles being minimal. Then all minimals of an unknown can be compared to this library.

by **tarek** » Fri Apr 06, 2012 8:48 pm

ronk wrote:This scenario points out the importance of a library of hardest puzzles being minimal. Then all minimals of an unknown can be compared to this library.

This reminds me of a wiki user's claim about a hardest puzzle that turned out to be an isomorph of a puzzle posted originally by ocean. MOST of the special puzzles (hardest or others) are best kept in a database for people to check against (I do that

). So in short I do agree with ronk on this. The puzzles on gsf's q1/q2 list should be the start of such a hardest puzzles list. I should be updating the (hardest sudoku thread 2) in May. That means that I will have a database of at least all puzzle posted in that thread which I can share through a link.

by **JC Van Hay** » Wed Apr 11, 2012 9:40 pm

"Weekly Unsolveable" AS#50, here - SE9.0

000700086028010700000003000905000003070040050200000407000600000004000510530002000

Code: Select all: #1. r7c6.r9c4=14; +2r7c3, +2r8c9, +4r4c2, +5r7c5; +6r9c78 :=> -6r9c3 #2. {2R15} : Skyscraper(2)(r1c5=r1c7-r5c7=r5c4) :=> -2r3c4.r4c5 #3. {1N5 79C3 1R9 8R3 4N4 2C8} :=> -2r3c5 +--------------------+------------------------+--------------------+ | 134 159 13(9) | 7 (29) 459 | 1239 8 6 | | 346 2 8 | 459 1 4569 | 7 349 459 | | 1467 1569 16(79) | 459(8) 69-2(8) 3 | 129 49(2) 1459 | +--------------------+------------------------+--------------------+ | 9 4 5 | (128) 678 1678 | 1268 6(2) 3 | | 1368 7 136 | 12389 4 1689 | 12689 5 189 | | 2 168 136 | 13589 3689 15689 | 4 69 7 | +--------------------+------------------------+--------------------+ | 178 189 2 | 6 5 14 | 389 3479 489 | | 678 689 4 | 389 3789 789 | 5 1 2 | | 5 3 (179) | 4(1) 789 2 | 689 4679 489 | +--------------------+------------------------+--------------------+ (2=9)r1c5-9r1c3=HP(79)r39c3-1r9c3=1r9c4-1r4c4=*SWing[8r3c5=8r3c4-(8=*2)r4c4-2r4c8=2r3c8] => 2r1c5=8r3c5=2r3c8 :=> -2r3c5; +2r1c5 #4. {1R49 8B64 1B4 } :=> -1r5c4 +----------------------+----------------------+----------------------+ | 134 159 139 | 7 2 459 | 139 8 6 | | 346 2 8 | 459 1 4569 | 7 349 459 | | 1467 1569 1679 | 4589 689 3 | 129 249 1459 | +----------------------+----------------------+----------------------+ | 9 4 5 | 28(1) 678 678(1) | 26(18) 26 3 | | 36(18) 7 36(1) | 2389-1 4 1689 | 1269(8) 5 19(8) | | 2 6(18) 36(1) | 13589 3689 15689 | 4 69 7 | +----------------------+----------------------+----------------------+ | 178 189 2 | 6 5 14 | 389 3479 489 | | 678 689 4 | 389 3789 789 | 5 1 2 | | 5 3 79(1) | 4(1) 789 2 | 689 4679 489 | +----------------------+----------------------+----------------------+ 1r4c46=(1-8)r4c7=8r5c79-8r5c1=(8-1)r6c2=[1r5c13=]1r6c3-1r9c3=1r9c4 => 1r4c46=1r5c13=1r9c4 :=> -1r5c4 #5. {5C4 5R1 1R49 1C29} :=> -1r6c4 +---------------------+------------------------+----------------------+ | 134 9(15) 139 | 7 2 49(5) | 139 8 6 | | 346 2 8 | 49(5) 1 4569 | 7 349 459 | | 1467 569(1) 1679 | 489(5) 689 3 | 129 249 459(1) | +---------------------+------------------------+----------------------+ | 9 4 5 | 28(1) 678 678(1) | 268(1) 26 3 | | 1368 7 136 | 2389 4 1689 | 12689 5 89(1) | | 2 68(1) 136 | 389-1(5) 3689 15689 | 4 69 7 | +---------------------+------------------------+----------------------+ | 178 89(1) 2 | 6 5 14 | 389 3479 489 | | 678 689 4 | 389 3789 789 | 5 1 2 | | 5 3 79(1) | 4(1) 789 2 | 689 4679 489 | +---------------------+------------------------+----------------------+ Kite(5)(r6c4=r23c4-r1c6=r1c2)-1r1c2=*Jellyfish(1)[r4c46=r4c7-r5c9=r3c9-r3c2=*[r6c2=]r7c2-r9c3=r9c4] => 5r6c4=1r4c46=1r6c2=1r9c4 :=> -1r6c4 #6. {1R69 8B46 7N1 7C8 2B6 6C8 6B4 3R5 2C4} :=> -1r4c4; 3 Singles +----------------------+-----------------------+------------------------+ | 134 159 139 | 7 2 459 | 139 8 6 | | 346 2 8 | 459 1 4569 | 7 349 459 | | 1467 1569 1679 | 4589 689 3 | 129 249 1459 | +----------------------+-----------------------+------------------------+ | 9 4 5 | 8-1(2) 678 1678 | 16(28) (26) 3 | | 1(368) 7 1(36) | 89(23) 4 1689 | 169(28) 5 19(8) | | 2 (168) 3(16) | 3589 3689 5689(1) | 4 9(6) 7 | +----------------------+-----------------------+------------------------+ | (178) 189 2 | 6 5 14 | 389 349(7) 489 | | 678 689 4 | 389 3789 789 | 5 1 2 | | 5 3 79(1) | 4(1) 789 2 | 689 49(67) 489 | +----------------------+-----------------------+------------------------+ 1r9c4=1r9c3 1r6c6=1r6c3=1r6c2 8r6c2=8r5c1 8r5c79=8r4c7 1r7c1=======8r7c1=======7r7c1 7r7c8=7r9c8 2r4c7============2r5c7=2r4c8 6r9c8=======6r4c8=6r6c8 6r6c2=6r5c1===============================6r6c3=6r5c3 3r5c1===================3r5c4=============3r5c3 2r4c4=====================================2r5c4 => 1r9c4=1r6c6=2r4c4 :=> -1r4c4; +1r9c4, +4r7c6, +4r1c1 #7. {4C48 2C8 4N4 8R3 9N35} :=> -59r9c8; stte +------------------+----------------------+----------------------+ | 4 159 139 | 7 2 59 | 139 8 6 | | 36 2 8 | 59(4) 1 569 | 7 39(4) 459 | | 167 1569 1679 | 59(48) 69(8) 3 | 129 9(24) 1459 | +------------------+----------------------+----------------------+ | 9 4 5 | (28) 678 1678 | 1268 6(2) 3 | | 1368 7 136 | 2389 4 1689 | 12689 5 189 | | 2 168 136 | 3589 3689 15689 | 4 69 7 | +------------------+----------------------+----------------------+ | 178 189 2 | 6 5 4 | 389 379 89 | | 678 689 4 | 389 3789 789 | 5 1 2 | | 5 3 (79) | 1 (789) 2 | 689 6-79(4) 489 | +------------------+----------------------+----------------------+ 4r9c8=[4r3c4=4r2c4-4r2c8=*(4-2)r3c8=2r4c8-(2=8)r4c4]-8r3c4=8r3c5-(8=79)r9c35 => 4r9c8=79r9c35 :=> -79r9c8; stte

by **champagne** » Thu Apr 12, 2012 1:29 pm

tarek wrote:
ronk wrote:This scenario points out the importance of a library of hardest puzzles being minimal. Then all minimals of an unknown can be compared to this library.

This reminds me of a wiki user's claim about a hardest puzzle that turned out to be an isomorph of a puzzle posted originally by ocean. MOST of the special puzzles (hardest or others) are best kept in a database for people to check against (I do that ). So in short I do agree with ronk on this. The puzzles on gsf's q1/q2 list should be the start of such a hardest puzzles list. I should be updating the (hardest sudoku thread 2) in May. That means that I will have a database of at least all puzzle posted in that thread which I can share through a link.

It seems that you did not look at that thread for a while

champagne

by **JC Van Hay** » Sun May 20, 2012 6:53 pm

"Weekly Unsolveable" AS#56, here - SE9.0

805000006010000002026010500060401000008000700000508060002040130500000080900000207

Hidden Text: Show

Code: Select all: #1. After LC and LS : +---------------------+----------------------+---------------------+ | 8 347(9) 5 | 2379 23(9) 23479 | 349 1 6 | | 347 1 3479 | 36789 5-8 345679 | 349(8) 479 2 | | 347 2 6 | 3789 1 3479 | 5 479 348 | +---------------------+----------------------+---------------------+ | 237 6 379 | 4 237 1 | 3(89) 2(59) 358 | | 1234 5 8 | 239 6 239 | 7 24 134 | | 12347 347(9) 3479 | 5 237 8 | 34(9) 6 134 | +---------------------+----------------------+---------------------+ | 6 78 2 | 78(9) 4 7(59) | 1 3 (59) | | 5 347 1347 | 12379 23(9) 2379 | 6 8 49 | | 9 348 134 | 1368 (58) 356 | 2 4(5) 7 | +---------------------+----------------------+---------------------+ Chain[8] : {59R7 5C8 8C7 9C25 9N5 9B6} :=> -8r2c5 8r2c7=(8-9)r4c7=*[5r9c8=(5-9)r4c8=*9r6c7-9r6c2=9r1c2-9r1c5=9r8c5-9r7c46=(9-5)r7c9=5r7c6]-(5=8)r9c5 => 8r2c7=8r9c5 :=> -8r2c5; 3 Singles, 1 LC #2. AIC[5] : 8r2c4=8r2c7-8r4c7=(8-5)r4c9=5r4c8-5r9c8=(5-6)r9c6=6r2c6 => 8r2c4=6r2c6 :=> -6r2c4; 4 Singles #3. AIC[5] : 2r1c4=2r5c4-2r5c8=(2-5)r4c8=5r4c9-(5=9)r7c9-(9=7)r7c4 => 2r1c4=7r7c4 :=> -7r1c4 #4. +------------------------+-------------------+----------------------+ | 8 3-47(9) 5 | 239 239 23479 | 49(3) 1 6 | | 37(4) 1 37(49) | 3789 5 6 | 9(348) 79(4) 2 | | (347) 2 6 | 3789 1 3479 | 5 479 4(38) | +------------------------+-------------------+----------------------+ | 237 6 379 | 4 2379 1 | 389 259 358 | | 1234 5 8 | 239 6 239 | 7 249 (134) | | 12347 347(9) 379(4) | 5 2379 8 | (349) 6 (134) | +------------------------+-------------------+----------------------+ | 6 8 2 | 79 4 579 | 1 3 59 | | 5 34(7) 3(47) | 1 239 239 | 6 8 9(4) | | 9 34 1 | 6 8 35 | 2 5(4) 7 | +------------------------+-------------------+----------------------+ Chain[12] : {4R2 7R8 4C3 9C2 3N1 6N7 56N9 9B1 38B3 4B9} :=> -47r1c2 9r1c2=9r6c2 9r6c7=3r6c7 3r5c9=1r5c9=4r5c9 3r6c9=1r6c9=4r6c9 4r8c9=4r9c8 3r12c7==================3r3c9 8r3c9=8r2c7 9r1c2===========================================9r2c3 4r2c8=======4r2c7=4r2c3=4r2c1* 7r3c1===============================3r3c1=============4r3c1** || 4r6c7 4r6c3=4r2c3=4r8c3 4r9c8=4r8c9 4r5c9=============1r5c9=3r5c9 4r6c9=============1r6c9=3r6c9 9r1c2=====================================9r2c3 4r2c7=4r2c8===================4r2c3=4r2c1* 4r6c3=========================4r2c3=======4r8c3 7r8c2=================================================7r8c3** * 9r1c2=4r2c13 :=> -4r1c2 ** 9r1c2=7r3c1=7r8c2 :=> -7r1c2 4 Singles, 1 NP, 1 LC #5. AIC[4] : 9r8c5=9r1c5-(9=3)r1c2-3r9c2=(3-5)r9c6=5r7c6 => 9r8c5=3r9c6 :=> -3r8c5 => 9r8c5=5r7c6 :=> -9r7c6 Singles only to the end.

by **Andrew Stuart** » Sun Sep 23, 2012 2:43 pm

I wasn't aware this was an isomoph of a previously published puzzle. But it's also not surprising that the occasional puzzle will be an isomoph of a known one - all the ones I publish are outputs of the creation software I've developed. It's in my job queue to get the canonical form stuff completed for easy comparison to the hard lists. I'm interested that #49 has extra clues which I'll look at.

by **tarek** » Sun Sep 30, 2012 2:41 pm

Hi Andrew,

I agree that there is a possibility of generating isomorphs with these qualities, However, unless a tedious neighbourhood search was done around carefully generated hard puzzle seeds (which is how the original was discovered) then I would say that the chances are slim. You can track the development of the Hardest Sudokus through the 2 dedicated threads to get a feel of how a tedious & laborious process it was to stumble upon these special puzzles. The puzzle in questions -although not the current hardest- has been influential at the time in developing new rating/solving and analysis systems of these beasts.

tarek

by **champagne** » Sun Sep 30, 2012 3:26 pm

tarek wrote: The puzzle in questions -although not the current hardest- has been influential at the time in developing new rating/solving and analysis systems of these beasts.

It has clearly been the puzzle where the exocet pattern has been shown, but moreover, this has been the start for an active search on complex logics leading to the discovery of huge rank 0 logic SLG's (although that one have none) , so I would say that is has been with Easter Monster a key puzzle for that development.

champagne

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Re: Andrew Stuart - Weekly Extreme 'Unsolveable' Sudoku Puzz

Re: Andrew Stuart - Weekly Extreme 'Unsolveable' Sudoku Puzz

Re: Andrew Stuart - Weekly Extreme 'Unsolveable' Sudoku Puzz

Re: Andrew Stuart - Weekly Extreme 'Unsolveable' Sudoku Puzz