The New Sudoku Players' Forum

by **SpAce** » Tue Sep 26, 2017 4:24 am

I said above that I like to take the path of least resistance, but I guess it's a relative term. On second thought, I may need to make some adjustments even if they're not absolutely necessary for solving success. For example:

Last weekend I solved another Nightmare (Feb 3, 2008) which turned out to be the most difficult (7.9) of them I've encountered so far: 040000030200503004007000600030409050000010000090205040008000400500706008070000090. Still, I guess it wasn't nearly as difficult as my solve path would suggest.

My solution used 18 chains and nets, some of which were pretty complicated. I did enjoy hunting them, but it's hard to justify the complexity if I look at the Hoduko solution which used only 9 chains, none of which were very complicated.

I suspect my biggest leak was that I skipped fishing as always. Seems that I need to start paying attention to that if I want to simplify my solve paths. There are other leaks, of course, but that seems the most obvious and perhaps easiest to fix first.

by **StrmCkr** » Tue Sep 26, 2017 5:07 am

What are those? I can find information about M-wings and L-wings you also mentioned but not those two.

in essence A.I.C / discontinuous/continuous Nice loops of 3/4 strong=weak links between 1-2 digits are classed and defined and finally named:

this post contains direct links for the other types i mentioned]

S-wing

the H-wing is used by a few people on here an a few other different forums and first appeared and was joking dubbed as a "purple cow" for us long timer

{which is still displayed as such in xsudoku! }

Code: Select all: .-----------------.-------------------.---------------------. | 1689 4 1569 | 1689 26789 1278 | 125789 3 12579 | | 2 168 169 | 5 6789 3 | 1789 178 4 | | 3 158 7 | 189 2489 1248 | 6 128 1259 | :-----------------+-------------------+---------------------: | 1678 3 126 | 4 678 9 | 1278 5 1267 | | 4678 568 2456 | 368 1 78 | 2789 2678 23679 | | 1678 9 16 | 2 3678 5 | 178 4 1367 | :-----------------+-------------------+---------------------: | 169 126 8 | 139 2359 12 | 4 1267 12567 | | 5 12 49 | 7 49 6 | 3 12 8 | | 146 7 3 | 18 2458 1248 | 125 9 1256 | '-----------------'-------------------'---------------------'

basics to this point then:
Almost Locked Set XY-Wing: A=r3c24568 {124589}, B=r8c5 {49}, C=r1268c3 {14569}, X,Y=4,5, Z=9 => r12c5<>9
W-Wing: 1/2 in r7c6,r8c8 connected by 2 in r78c2 => r7c89<>1
Finned Swordfish: 8 r146 c157 fr1c4 fr1c6 => r23c5<>8
Locked Candidates Type 1 (Pointing): 6 in b1 => r2c5<>6
followed by easy steps brings it to here:

Code: Select all: .----------------.-----------------.-------------------. | 189 4 159 | 6 28 128 | 12579 3 12579 | | 2 168 169 | 5 7 3 | 19 18 4 | | 3 158 7 | 189 249 1248 | 6 128 125 | :----------------+-----------------+-------------------: | 1678 3 126 | 4 68 9 | 1278 5 127 | | 48 58 245 | 38 1 7 | 289 6 239 | | 1678 9 16 | 2 368 5 | 178 4 137 | :----------------+-----------------+-------------------: | 169 126 8 | 139 2359 12 | 4 7 256 | | 5 12 49 | 7 49 6 | 3 12 8 | | 146 7 3 | 18 2458 1248 | 125 9 1256 | '----------------'-----------------'-------------------'

Almost Locked Set XY-Wing: A=r1c156 {1289}, B=r23c8,r3c9 {1258}, C=r7c1269 {12569}, X,Y=5,9, Z=1,2 => r1c79<>1, r1c79,r3c56<>2
Almost Locked Set XY-Wing: A=r2c238 {1689}, B=r126c3 {1569}, C=r1c79,r2c7 {1579}, X,Y=1,5, Z=9 => r1c1,r8c3<>9
more basic steps:

Code: Select all: .---------------.-------------.--------------. | 18 4 59 | 6 2 18 | 579 3 579 | | 2 16 169 | 5 7 3 | 19 8 4 | | 3 58 7 | 9 4 18 | 6 2 15 | :---------------+-------------+--------------: | 1678 3 126 | 4 68 9 | 1278 5 127 | | 4 58 25 | 38 1 7 | 289 6 239 | | 1678 9 16 | 2 368 5 | 178 4 137 | :---------------+-------------+--------------: | 9 16 8 | 13 35 2 | 4 7 56 | | 5 2 4 | 7 9 6 | 3 1 8 | | 16 7 3 | 18 58 4 | 25 9 256 | '---------------'-------------'--------------'

Almost Locked Set XZ-Rule: A=r1246c3 {12569}, B=r12456c7 {125789}, X=5, Z=2 => r4c9<>2
Almost Locked Set XZ-Rule: A=r15c3 {259}, B=r134679c9 {1235679}, X=9, Z=2 => r5c9<>2

singles to the end.

by **ghfick** » Tue Sep 26, 2017 12:23 pm

champagne wrote:
Here, we have an heavily downgraded form of potential exocet for the base r12c9 target r6c7 r7c8

1 in the base => 1r7c8
5 in the base => 5r6c7

if you can prove that 4 in the base => 4 (r6c7,r7c8) you have an exocet.

Junior exocet in the most common pattern to prove it and is there in most cases.
In other cases "classical AICs" can establish it

Using the [hidden] UR : r16c79 with {4,5} we see that r6c7 <> 4. So to have an exocet here, we would need to prove that 4 in the base => 4r7c8. Alas, there does not appear to be such a proof.
Can you suggest [or point to] a tough puzzle that contains a 'real' exocet that is not Junior?
David P Bird's compendium contains a section on the 'Senior Exocet'. You are suggesting a different type of extension where the base cells and target cells are in the same band but the 'S' cell requirement is not met.
The use of AICs in this situation suggests some commonalities with Krakens.

by **David P Bird** » Tue Sep 26, 2017 4:45 pm

GF the 'Senior Exocet' variation described in the compendium allows target cells to be outside the base cell band. It can just about be classed as a recognisable pattern as it consists of a defninite number of elements that can be checked without needing to track chains. But Champagne's base cells and targets are all in the same band so it does not apply.

As Champagne is willing to accept inference tracking using chains or nets as a means of proving that a pattern exists, he has greater freedom to confirm the pattern is an Exocet.

Champagne, I hope that this contribution makes your life easier as it should save you from having to either read for the first time or revise the defintion of a Senior Exocet!

David
.

by **SpAce** » Mon Oct 02, 2017 10:34 pm

Thanks for the info, StrmCkr!

by **SpAce** » Thu Mar 22, 2018 11:28 am

Back to where I started. I finally decided to face my original nemesis a third time and see if I'd learned anything in half a year. As told above, my very first attempt on that particular SE 8.4 puzzle failed miserably. As also told, my second attempt sort of solved it, but I wasn't at all happy about how it happened, so I never really counted it. It's been bugging me a bit, but I never looked at the puzzle again until now. Here's what I came up with (unedited p&p steps):

1. AIC (AHS): (6)r3c1 = r3c4 - r1c5 = (6-4)r4c5 = r8c5 - r7c4 = (41-6)r7c89 = (6)r8c9 => -6 r8c1
2. AIC-Loop (ANS, Grouped): (2)r8c4 = (2-4)r7c4 = r7c89 - (4=[9]2)r8c78 - loop => -35 r7c4, -2 r8c1; -9 r8c16, r7c89, r9c79
3. AIC: (2=7)r9c7 - (7=9)r3c7 - r8c7 = (9)r8c8 => -2 r8c8
4. AIC-Hydra (ANS): (#2)r4c8 = r7c8 - (2=94)r8c78 - (4)r8c5 = (#4-1|6)r4c5 = (61)r12c5 - (1=5)r2c9 - r6c9 = (#5)r6c7 => -4 r4c8, -2 r6c7
5. AIC-Hydra (AHS): (#5)r8c6 = (5-#2)r8c4 = (2-4)r7c4 = (41-3)r7c89 = r9c9 - (3=#8)r9c5 => -8 r8c46
6. AIC-Loop (Grouped): (8)r6c3 = r9c3 - (8=3)r8c8 - r79c3 = (3)r6c3 - loop => -2 r6c3; -3 r7c12, r9c2
7. AIC-Hydra: (#8)r4c4 = r6c4 - r6c3 = r9c3 - r9c5 = (8-4)r8c5 = (#4-6)r4c5 = r1c5 - (6=#3)r3c4 => -34 r4c4
8. Kite: (6)r3c1 = r3c4 - r1c5 = (6)r4c5 => -6 r4c1
9. AIC (ANS): (5=1)r2c9 - r2c5 = (1-6)r1c5 = (6-4)r4c5 = r8c5 - (4=92)r8c78 - (2=7)r9c7 - r9c9 = (7)r6c9 => -5 r6c9
10. Kraken Cell: (1378)r1c4 => -26 r1c2 (*a)
11. AIC: (7)r3c8 = r3c7 - (7=2)r9c7 - r7c8 = (2)r4c8 => -7 r4c8
12. Kraken Cell (Nested, ANS): (157)r5c6 => -7 r5c8 (*b)
13. AIC: (2=6)r1c3 - r1c5 = (6-4)r4c5 = r8c5 - (4=2)r7c4 => -2 r7c3
14. Kraken Cell (Grouped): (3467)r4c2 => +8 r6c3 (*c)
15. AIC: (6)r5c4 = r4c5 - (6=1)r1c5 - r1c7 = r4c7 - (1=4)r5c8 => -4 r5c4
16. AIC: (3)r2c5 = (3-6)r3c4 = (6-5)r5c4 = r8c4 - (5=3)r8c6 => -3 r8c5
17. Skyscraper: (6)r1c3 = r5c3 - r5c4 = (6)r3c4 => -6 r3c1, r1c5; stte

Details for (*a, *b, *c):

Hidden Text: Show

Looking back at my first two pathetic attempts (just found the notes and laughed)... yeah, I think I've learned something

For that I can thank a lot of people here, mostly the same ones who kindly replied to this very first post of mine and gave tips on how to move forward. Still a lot to learn.

The one thing that hasn't changed, however, is the pencil&paper solving system I developed last year. It's been stable since October, and I can't think of any more improvements (to the core at least). I'm very happy with it, except for the slowness. That's why my next ambition would be to turn it into software, but we'll see if that ever happens. Until then I'm stuck with p&p. (I'm not principled about that at all -- I'd switch to computerized solving immediately if any program had the features I want, but none do.)

The puzzle (again):

000900030004700600081054002005000000000020308000090060000070800017000000400106050

by **creint** » Thu Mar 22, 2018 9:02 pm

With computerized solving do you mean: support for manual inputting logic?
What options should the program have and whats wrong with xsudo?
Maybe i can add some things to my solver.

by **SpAce** » Fri Mar 23, 2018 1:10 am

creint wrote:With computerized solving do you mean: support for manual inputting logic?

I'm not quite sure what you mean by that. I haven't used Xsudo so I don't really know how it works in that.

What options should the program have?

What I really want is the same unique way of representing the candidate grid (+ some helper views) which I now draw by hand. Without it I wouldn't be able to solve harder puzzles, or at least it would be painful. In the playing mode I don't want any features that I wouldn't be able to do manually on paper, and I don't want it to make cheating too easy when stuck. In other words, I want it to provide tools for solving but not solve for me (unless I specifically ask for it, but then I'm no longer playing). For training, practicing, and post-game analysis the program should have other features as well -- but most what I want I already have in Hodoku, for example.

The main benefits of a software implementation of my system would be speed, better graphics, and automated syncing of multiple views. Reliability is not an issue, as I usually solve months without making a single mistake (and I do everything by hand, including basics).

and whats wrong with xsudo?

The first thing wrong with it is that it requires Windows, which is why I can't say much about else. I guess I could install it on a virtual box but I haven't been interested enough yet. It also seems to require a bit different solving philosophy, but that's not necessarily a bad thing. I think it might be especially good for solving or at least understanding some really difficult puzzles that aren't solvable with any "normal" methods. I don't think I'll be having such ambitions any time soon.

Maybe i can add some things to my solver.

Is your solver publicly available? I've understood from your other posts that it supports all kinds of sudoku variants, which is cool.

by **champagne** » Fri Mar 23, 2018 3:18 am

David P Bird wrote:GF the 'Senior Exocet' variation described in the compendium allows target cells to be outside the base cell band. It can just about be classed as a recognisable pattern as it consists of a defninite number of elements that can be checked without needing to track chains. But Champagne's base cells and targets are all in the same band so it does not apply.
David
.

Hi David,

I did not work on that topic for long, but the definition of an exoccet accepts the 2 cells in any place. At the very beginning, I explored all cells pairs. Later, when the JE appeared and lacking of interesting examples with cells outside the band, I concentrated on a band.

Later this year, I could restart some exploration on potential hardest with no known exotic pattern.

by **David P Bird** » Fri Mar 23, 2018 8:02 am

Champagne,

You wrote:Later this year, I could restart some exploration on potential hardest with no known exotic pattern.

I look forward to seeing what you can find!

One area that might be worth exploring is Almost Multifish (or Almost MSLS), where the list of pattern elimination cells includes one false one. Sometimes, but not often, it is possible to adjust the cover sets to correct this. It would be interesting to see if you can identify which of the eliminations must be right. PJP is also interested in this and his solver uses some brute force checking to find them I believe.

David
.

by **champagne** » Fri Mar 23, 2018 10:40 am

Hi David,

I remember to have tried to combine several "rank 1" logic systems to produce a new exotic pattern, without succes at that time. Using a "rank 1" logic in a chain as some do with ALS is not a big problem, but following eleven's remarks, this is usually not a process that a manual player could apply.

We'll reopen the discussion in due time.

by **yzfwsf** » Thu May 07, 2020 8:12 am

Hi SpAce:
I hope it's useful for you.

Code: Select all: puz skfr Hodoku 020000003400200800007080020100030500000005004006400080030001009005700060600090400 83/12/12 15996 000000603400100000050002010100005700009800004025060090003000900200000030040200006 83/12/12 15708 200600900085002006004050000000700009000004075030010400006080090040001200000300000 83/12/12 13768 007005004300007600090300010004030200000100008070002060050060080630000100009500000 83/12/12 13510 000600070060703009000000300080009050006280003400030800010020500200001900009800002 83/12/12 13062 800100902000090070009005001020009800600070000050600007000006080300810006000050400 83/12/12 13044 008003040000400006900028300006300007800005600050040090000050100200007009080900060 83/66/66 13042 600000050008300100000020008520800060104070000009005002040700090900004600800000005 83/12/12 12540 010000040002400006900068000070000004300000017005100800030004050004800601500010003 83/12/12 12508 050007030002805009300040600006700004090000000500016070005008000070400100400000002 83/12/12 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010700900500006008007040000300060800060009004009500020030200400200000085001008002 83/83/66 11612 008500002000010090000003500503040000004700006000001070200006001000070300060100080 83/12/12 11600 700100090001000400080050002040000030500080009003010700004600000000009203900020005 83/12/12 11578 004800300050002008000050020080400009300006080000010600100060000000200075008004060 83/12/12 11524 010006000009800000705010009040600300200001080006400001050008060600070900004100005 83/12/12 11516 030008050700050006009200800070006020200100600005000074090000700500002000007900040 83/12/12 11512 800009060094060000000200100020900080600008004007010300010030500500000000008000002 83/12/12 11478 020800000000700006003060080002300508054002000900070300010007004200500000000010060 83/12/12 11464 010000203000100700005260010030007000600010005004900070080000400400002030003080060 83/12/12 11452 001006009000400700700090040006004002030500080000030400000009020020700004300010900 83/12/12 11450 020060300000004008900200004000570006000002090002900100069020500300800000050003070 83/12/12 11434 040600900001005002700010060006700400000000020002001009007090006900000080050800300 83/12/12 11430 600090080050300000002800006003200017900000400070050800004900008000005600030080020 83/12/12 11418 500080000008106900030000010400020300070800020005090001004900003000032070000000600 83/15/15 11414 004090052800007060000400300000000040080005700009100006500006007060008010001020000 83/12/12 11412 900100600002006009000070040200007008009010006080900200605000003000031000030000070 83/12/12 11400 700090005000003700090000060500800010020076000004001003300060800050008004001500000 83/12/12 11400 004008050900070006070300800600000030040010900000204008007000001000100090100096400 83/12/12 11370 900000007000001080804500600001000000402003090090400003040090706000600000100007200 83/20/20 11368 004090000800002050020600100003204000700100004040070290009003060000060500000700000 83/12/12 11354 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