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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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 Posted: Sun Jan 09, 2011 9:01 pm Post subject: |
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Ted, since Danny stopped posting puzzles I have strayed to look at extreme puzzles! Almost moves seems "almost" essential and some very clever stuff can be done with AALS type moves.
I have posted this move as an example of the ridiculous over-the-top moves you can construct this way 
There is an AALS(358) in r2 with the additional candidates (2)r2c3 and (2)r2c5.
There is an almost s-wing-like(13) (I call them two-eyed!) marked a/b in the grid with (18)r5c2 and (38)r5c5 bivalues.
All the "almosts" conspire to eliminate (3)r2c7 - which cracks the puzzle!
| Code: | *---------------------------------------------------------------*
| 358 238 7 | 234 1 48 | 9 58 6 |
| 6 a1238 (58)+2| 9 (38)+2 7 | a15-3 b(358) 4 |
| 1389 4 89 | 5 38 6 | 7 2 13 |
|--------------------+---------------------+--------------------|
| 149 7 3 | 12 (245) 159 | 8 6 159 |
| 2 (18) 489 | 6 (38)+45 4589 | 15 b35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
|--------------------+---------------------+--------------------|
| 458 9 458 | 7 (45) 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 35 |
| 7 (2)(3) (2)45 | 14 6 145 | (3)5 9 8 |
*---------------------------------------------------------------*
Kraken aals(358) with two-eyed s-wing(13) ; r2c7<>3
nt(358)r2c358
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(2)r2c3 - r9c3=(2-3)r9c7
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(2)r2c5 - (2=45)r47c5 - (45)r5c5=s-wing-like(13)[(1)r2c7=r2c2 - (1=8)r5c2-(8=3)r5c5 - (3)r5c8=r2c8] |
(Disclosure - I knew the elimination was powerful!) |
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JV
Joined: 09 Jan 2011
Posts: 24
Location: Devon, England
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| Posted: Sun Jan 09, 2011 11:30 pm Post subject: prequel |
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Hi folks. I often meant to join this forum but never got round to it until now. I gave up sudoku 2 or 3 years ago but am now having another go. I tried a couple of Daily S VHs and that went OK, and then saw this posted Menneske (used to be able to do some, not others). I decided to start from scratch, to see if I could at least get as far as Marty but I can't, despite looking at it off and on for a few days.
Here's the start:
| Code: |
+----------------+----------------+--------------+
| 3589 238 7 | 234 1 48 | 359 358 6 |
| 6 1238 1258 | 9 238 7 | 135 358 4 |
| 1389 4 189 | 5 38 6 | 7 2 139 |
+----------------+----------------+--------------+
| 149 7 3 | 124 245 1459 | 8 6 159 |
| 2 18 1489 | 6 3458 14589 | 1359 35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
+----------------+----------------+--------------+
| 458 9 458 | 7 45 3 | 6 1 2 |
| 135 6 15 | 8 9 2 | 4 7 35 |
| 7 23 245 | 14 6 145 | 35 9 8 |
+----------------+----------------+--------------+
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Play this puzzle online at the Daily Sudoku site
(1) You'll see a skyscraper (or is it a kite?) in 9s - strong links in c3 & c7, which removes the 9 in r3c9.
(2) The exposed 13 in r3c9 forms part of an XY-wing which removes the 1 in r3c3.
(3) There's an X-wing in 1s in c2 & c7 - sundry 1s removed.
(4) There's a finned X-wing in 4s - c1 & c5, which removes a couple of 4s in r4.
That leaves us with:
| Code: |
+---------------+----------------+-------------+
| 358 238 7 | 234 1 48 | 9 358 6 |
| 6 1238 258 | 9 238 7 | 135 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 13 |
+---------------+----------------+-------------+
| 149 7 3 | 12 245 159 | 8 6 159 |
| 2 18 489 | 6 3458 4589 | 135 35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
+---------------+----------------+-------------+
| 458 9 458 | 7 45 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 35 |
| 7 23 245 | 14 6 145 | 35 9 8 |
+---------------+----------------+-------------+
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Play this puzzle online at the Daily Sudoku site
One fewer move than Marty, & one small difference, the 3 that is / isn't in r5c7. Hope Marty has kept his notes!
(In fact, I could only find one more move, a 5-link chain of 5s from r7c5 to the pair r5c78 - or r4c56. This eliminates the 5 in r5c5.)
Help!
James V |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Jan 10, 2011 1:15 am Post subject: |
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James, welcome to the forum. I did keep some notes but they're a mess.
Your move on 9s is a Skyscraper; Kites have the strong links running perpendicularly.
| Quote: | | (In fact, I could only find one more move, a 5-link chain of 5s from r7c5 to the pair r5c78 - or r4c56. This eliminates the 5 in r5c5.) |
I don't think this is valid. Both the start and end of the chain are both 5s or both <>5. Coloring chains of this type need to have an even number of cells so the start and end have opposite "polarity." That is, one or the other must be true. That's not the case with your odd number of cells. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Jan 10, 2011 2:26 am Post subject: |
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Here is JV's chain (reading from right-to-left)
| Code: | (5)r4c56 = r4c9 - r8c9 = r9c7 - r9c6 = (5)r7c5 => r5c5<>5
(5)r5c78 /
+---------------------------------------------------------------+
| 358 238 7 | 234 1 48 | 9 358 6 |
| 6 1238 258 | 9 238 7 | 135 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 13 |
|--------------------+---------------------+--------------------|
| 149 7 3 | 12 f245 f159 | 8 6 e159 |
| 2 18 489 | 6 348-5 4589 | f135 f35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
|--------------------+---------------------+--------------------|
| 458 9 458 | 7 a45 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 d35 |
| 7 23 245 | 14 6 b145 | c35 9 8 |
+---------------------------------------------------------------+
# 68 eliminations remain
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James: at this point, the alternatives aren't pretty. You should reference Peter's and/or my steps above.
Marty: cells a+c+e are Green and b+d+ff are Blue. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Jan 10, 2011 4:55 am Post subject: |
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| Quote: | | Marty: cells a+c+e are Green and b+d+ff are Blue. |
I misread his chain and was thinking r4c5 rather than r5c5. Other than that I had it right.  |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Jan 10, 2011 8:09 am Post subject: Re: prequel |
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| JV wrote: | | One fewer move than Marty, & one small difference, the 3 that is / isn't in r5c7. Hope Marty has kept his notes! |
James, welcome also.
Funnily enough I had the same question when I first looked at this puzzle as I just copy/pasted the givens and stepped through the easy moves. The only difference was that (3)r5c7!
I don't know what move Marty made but there is an s-wing that makes this deletion.
If you are not familiar, an s-wing is a bilocation strong link on digit X connected to a bilocation strong link on digit Y via bivalue (X=Y). If the ends of the bilocations are in the same house then X can be eliminated from the end of Y and Y from the end of X. If you work it through you will see at least one end of the wing must be true.
As in...
| Code: | +---------------+----------------+----------------+
| 358 238 7 | 234 1 48 | 9 358 6 |
| 6 1238 258 | 9 238 7 | (1)35 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 (13)|
+---------------+----------------+----------------+
| 149 7 3 | 12 245 159 | 8 6 159 |
| 2 18 489 | 6 3458 4589 | (1)5-3 35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
+---------------+----------------+----------------+
| 458 9 458 | 7 45 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 (3)5|
| 7 23 245 | 14 6 145 | (3)5 9 8 |
+---------------+----------------+----------------+
(1)r7c5=r2c7 - (1=3)r3c9 - (3)r8c9=r9c7 ; r5c7<>3 |
Having said that I can't recall Marty using s-wings  but they often come with m-wings which he is an expert user of. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Jan 10, 2011 4:03 pm Post subject: |
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Marty also loves W-Wings!
| Code: | after basics, X-Wing, and finned X-Wing on solved candidates
+--------------------------------------------------------------+
| 358 238 7 | 234 1 48 | 9 358 6 |
| 6 1238 258 | 9 238 7 | 135 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 13 |
|--------------------+--------------------+--------------------|
| 149 7 3 | 12 245 159 | 8 6 b159 |
| 2 18 489 | 6 3458 4589 | 15-3 a35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
|--------------------+--------------------+--------------------|
| 458 9 458 | 7 45 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 c35 |
| 7 23 245 | 14 6 145 | d35 9 8 |
+--------------------------------------------------------------+
# 68 eliminations remain
M-Wing 6A (3=5)r5c8 - r4c9 = (5-3)r8c9 = (3)r9c7 => r5c7<>3
W-Wing (3=5)r5c8 - r4c9 = r8c9 - (5=3)r9c7 => r5c7<>3
W-Wing (3=5)r5c8 - r12c8 = r2c7 - (5=3)r9c7 => r5c7<>3
S-Wing (8)r5c2 = r12c2 - (8=9)r3c3 - r5c3 = (9)r5c6 => r5c6<>8
S-Wing (1)r5c7 = r2c7 - (1=3)r3c9 - r8c9 = (3)r9c7 => r5c7<>3
S-Wing (1)r5c7 = r2c7 - (1=3)r3c9 - r12c8 = (3)r5c8 => r5c7<>3
S-Wing (1)r5c7 = r46c9 - (1=3)r3c9 - r8c9 = (3)r9c7 => r5c7<>3
S-Wing (1)r5c7 = r46c9 - (1=3)r3c9 - r12c8 = (3)r5c8 => r5c7<>3
S-Wing (1)r5c7 = r46c9 - (1=3)r3c9 - r8c9 = (3)r9c7 => r5c7<>3
S-Wing (1)r5c7 = r46c9 - (1=3)r3c9 - r12c8 = (3)r5c8 => r5c7<>3
L-Wing (2)r9c3 = r2c3 - r2c5 = (2-4)r1c4 = (4)r9c4 => r9c3<>4
L-Wing (2)r9c3 = r2c3 - r1c2 = (2-4)r1c4 = (4)r9c4 => r9c3<>4
L-Wing (2)r9c3 = r9c2 - r1c2 = (2-4)r1c4 = (4)r9c4 => r9c3<>4
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Marty: Don't you love being talked about in the third-person.  _
NOW ... read my updated message here. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Jan 10, 2011 4:42 pm Post subject: |
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| Quote: | | Having said that I can't recall Marty using s-wings |
Marty hasn't yet read a definition that he can understand.
| Quote: | | Marty: Don't you love being talked about in the third-person. |
Yes, as long as people fudge the truth. |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Mon Jan 10, 2011 6:01 pm Post subject: |
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| Blimey! I am seeing s-wings before w-wings (and Danny is seeing generalised remote pairs!) - need to reset my priorities! |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Jan 10, 2011 6:18 pm Post subject: |
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| Marty R. wrote: | | Quote: | | Having said that I can't recall Marty using s-wings |
Marty hasn't yet read a definition that he can understand.
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How about a working definition: it's based on the following S-Wing
| Code: | S-Wing (1)r5c7 = r2c7 - (1=3)r3c9 - r8c9 = (3)r9c7 => r5c7<>3
+--------------------------------------------------------------+
| 358 238 7 | 234 1 48 | 9 358 6 |
| 6 1238 258 | 9 238 7 | G135 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 B13P |
|--------------------+--------------------+--------------------|
| 149 7 3 | 12 245 159 | 8 6 159 |
| 2 18 489 | 6 3458 4589 | B15-3 35 7 |
| 189 5 6 | 13 7 189 | 2 4 139 |
|--------------------+--------------------+--------------------|
| 458 9 458 | 7 45 3 | 6 1 2 |
| 35 6 1 | 8 9 2 | 4 7 35A |
| 7 23 245 | 14 6 145 | 35P 9 8 |
+--------------------------------------------------------------+
# 68 eliminations remain
*) find a bivalue cell ... say r3c9=13
*) color r3c9=1 Blue, r2c7<>1 Green, and r5c7=1 Blue
*) color r3c9=3 Pink, r8c9<>3 Amber, and r9c7=3 Pink
*) at this point: r5c7 can not be Pink and r9c7 can not be Blue
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So, you can conclude: r5c7<>3 and r9c7<>1 (if a <1> was present) |
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JV
Joined: 09 Jan 2011
Posts: 24
Location: Devon, England
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| Posted: Mon Jan 10, 2011 7:52 pm Post subject: where did the 3 go |
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(1) Thanks Peter: I'd never heard of S wings, but I do follow. I'm not totally sure that I understand the precise definition of an S wing, but never mind - I see how this one works. (Is any AIC in two digits with a crossover in a bivalue cell an S wing?)
2) Marty, I owe you an apology: I wasn't sure of course, but I rather suspected that you'd just made a mistake with that 3. (I often made mistakes, part of the reason why I gave up.) I take from the jocular correspondence that you did it with an M-wing.
I'll try the rest of the puzzle myself before reading how it could be done. At least I now see a kite in 3s that removes the 3 in r1c7.
Thanks folks, JV .... which is actually what my friends & family call me - I never liked the name James |
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JV
Joined: 09 Jan 2011
Posts: 24
Location: Devon, England
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| Posted: Tue Jan 11, 2011 12:49 pm Post subject: |
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Daj: thanks for pointing out the M wing. I'm kicking myself: I did look at the pair of 35s but got the links wrong. (If you'd pointed out say a pair of ALSs I wouldn't be kicking myself, because I could never find them anyway.)
Practising posting a grid:
| Code: |
+---------------+----------------+-------------+
|(358 238)A 7 | 234B 1 48 | 9 58 6 |
| 6 1238 258 | 9 238 7 | 135 358 4 |
| 1389 4 89 | 5 38 6 | 7 2 13 |
+---------------+----------------+-------------+
| 149 7 3 | 124 245 1459 | 8 6 159 |
| 2 18 489 | 6 348 14589 | 15 35 7 |
| 189 5 6 | 13C 7 189 | 2 4 139D|
+---------------+----------------+-------------+
| 458 9 458 | 7 45 3 | 6 1 2 |
| 35F 6 1 | 8 9 2 | 4 7 35E |
| 7 23 245 | 14 6 145 | 35 9 8 |
+---------------+----------------+-------------+
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Removing the 3 from r1c7 leaves the pair of 3s in A strongly linked with the 3 in B --- and you can step round to F (all strong links as it happens). (I suppose that this is also a finned sfish.) So that removes the 3 in r3c1. And that exposes yet another kite in 3s, removing the 3 in r6c9. After that I had a look back at Peter's second kite in 8s, and that solves the puzzle. That's a splendid construction! - a new take on a familiar technique feels like sudoku art, where finding new techniques (which I admire though I've never found any myself) is sudoku science.
Now I'll go off and read about some of the new techniques mentioned - like AALSs. (Probably won't do me any good as far as actually solving anything goes - if I can't find ALSs I'm unlikely to find AALSs, whatever they are).
JV |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Jan 22, 2011 7:01 pm Post subject: |
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| Quote: | | Are you reserving "kite" for the case where there is only a weak link in the pivot block i.e the multi colouring case as opposed to the simple colouring case? In either case it's still a kite. |
In my book, kite and skyscraper refer to the multicoloring case, where the base is a weak link. It makes a difference.
In the simple coloring case (base is a strong link), one of the pincers is true.
In the multicoloring case, one OR BOTH of the pincers are true.
The same distinction holds for a remote pair (one of the pincers is true) and a W-wing (one or both are true). (If all the links in a W-wing are strong, you have a remote pair.)
Keith |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Sun Jan 23, 2011 10:27 am Post subject: |
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in pictures...
(3=5)r5c8 - (5)r4c9 = (5)r8c9 - (5=3)r8c1 - (3=2)r9c2 - (2)r1c2 = (2)r1c4 - (2=1)r4c4 - (1=3)r6c4;
r6c9 <> 1
r5c5 <> 3
r6c9 <> 3
(5=3)r9c7 - (3)r8c9 = (3)r3c9 - (3=8)r3c5 - (8=4)r1c6 - (4)r1c4 = (4)r9c4 - (4=5)r7c5; r9c6 <> 5
almost x-wing
[x-wing(8)r12c28] = (8)r5c2 - (8)r5c56 = (8)r56c6; r1c6 <> 8
(3=5)r9c7 - (5=1)r5c7 - (1=8)r5c2 - (8=3)r1c2; r9c2 <> 3 |
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royalina
Joined: 21 Feb 2011
Posts: 4
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| Posted: Mon Feb 21, 2011 6:46 am Post subject: |
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| I just realized that I was describing a 6-cell W-Wing. Aaaagh!]。。。。 |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Wed Feb 23, 2011 6:19 pm Post subject: |
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So much complication for a puzzle that can be solved in 4 steps with standard advanced techniques starting from that first grid with the c3 singleton <1> placed:
[1] Sashimi SF r358; r6c9<>3
[2] FXW c56; r5c5<>5
[3] FSF c268; r5c5<>8
[4] BUG+1; r2c2=8 |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Feb 23, 2011 8:45 pm Post subject: |
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| Asellus wrote: | | So much complication for a puzzle that can be solved in 4 steps with standard advanced techniques ... |
Other than wapati (and now you), the use of finned/Sashimi Swordfish are not part of the "standard" solving techniques employed. |
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