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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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 Posted: Wed Feb 17, 2010 4:48 pm Post subject: Menneske SH |
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This is #5264795, rated SH (18 ), a level that I normally solve without too much difficulty. It's puzzles like this that make me rue the day I ever learned about this idiotic activity. 
At any rate, I can't do a thing with this one, not one move beyond basics (haven't yet tried Medusa).
| Code: |
+-----------------+---------+--------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 4569 69 | 1 2 3 | 4789 789 456 |
| 346 13469 1369 | 5 8 7 | 49 2 346 |
+-----------------+---------+--------------+
| 8 36 4 | 7 35 69 | 2 59 1 |
| 1 2 36 | 8 35 69 | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+-----------------+---------+--------------+
| 456 14569 169 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | 48 138 34 |
+-----------------+---------+--------------+
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Play this puzzle online at the Daily Sudoku site |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Feb 17, 2010 9:13 pm Post subject: |
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| Although there's a short chain that cracks this puzzle, I suspect they're looking for an ALS. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Wed Feb 17, 2010 11:10 pm Post subject: |
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| daj95376 wrote: | | Although there's a short chain that cracks this puzzle, I suspect they're looking for an ALS. |
Thanks Danny. A couple of years ago I learned the rules for ALS, but never learned how to efficiently look for them and don't try anymore. I'll spend a few minutes looking for the chain, otherwise I'll do the Medusa thing. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Feb 18, 2010 1:33 am Post subject: |
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Marty,
I can make a little headway: | Code: | +-------------------+-------------------+-------------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 4569 69@ | 1 2 3 | 4789 789# 456 |
| 346 13469 13-69 | 5 8 7 | 49 2 346 |
+-------------------+-------------------+-------------------+
| 8 36% 4 | 7 35 69@ | 2 59# 1 |
| 1 2 36% | 8 35 69 | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+-------------------+-------------------+-------------------+
| 456 14569 1-69 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | 48 138 34 |
+-------------------+-------------------+-------------------+ |
@ are a 69 W-wing connected in # by 9. Pincer transport % in 6 takes out 6 in two cells in C3.
| Code: | +-------------------+-------------------+-------------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 456-9 69@ | 1 2 3 |478-9 789* 456 |
| 346 13469 139 | 5 8 7 | 49 2 346 |
+-------------------+-------------------+-------------------+
| 8 36 4 | 7 35 69@ | 2 59* 1 |
| 1 2 36& | 8 35 69& | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+-------------------+-------------------+-------------------+
| 456 14569 19 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | 48 138 34 |
+-------------------+-------------------+-------------------+ |
The same cells are also connected by 6 in &. (A double W-wing, they are a remote pair.) Pincer extension * takes out 9 in two cells in R2.
Now, what? We are here: | Code: | +-------------------+-------------------+-------------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 456 69 | 1 2 3 | 478 789 456 |
| 346 13469 139 | 5 8 7 | 49 2 346 |
+-------------------+-------------------+-------------------+
| 8 36 4 | 7 35 69 | 2 59 1 |
| 1 2 36 | 8 35 69 | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+-------------------+-------------------+-------------------+
| 456 14569 19 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | 48 138 34 |
+-------------------+-------------------+-------------------+ |
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Feb 18, 2010 2:00 am Post subject: |
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| Nice catch on the W's Keith. I missed them. I see a 15-9 XY-Wing which takes out a 9 with transport, but it doesn't seem to accomplish anything. By the time I read your post I had failed to see Danny's chain, so I Medusa'ed it and it easily solved. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Feb 18, 2010 2:13 am Post subject: |
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Keith,
just fyi,
there isn't a need to see the w-wing connected by the 6's...
since your extended w-wing 6,9 in your first grid is a loop, then the 9's in row 2 are eliminated in that step as well.
| Code: | +--------------------+-------------+-------------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 456-9 (69) | 1 2 3 | 478-9 78(9) 456 |
| 346 13469 139-6 | 5 8 7 | 49 2 346 |
+--------------------+-------------+-------------------+
| 8 3(6) 4 | 7 35 (69) | 2 5(9) 1 |
| 1 2 3(6) | 8 35 69 | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+--------------------+-------------+-------------------+
| 456 14569 19-6 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | 48 138 34 |
+--------------------+-------------+-------------------+ |
leaves this chain...
| Code: | +------------------+-----------+-------------------+
| 357 8 2 | 9 6 4 | 1 37 35 |
| 4567 456 69 | 1 2 3 | 47(8) 7(89) 456 |
| 346 19 139 | 5 8 7 | -4(9) 2 346 |
+------------------+-----------+-------------------+
| 8 36 4 | 7 35 69 | 2 59 1 |
| 1 2 36 | 8 35 69 | 59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+------------------+-----------+-------------------+
| 456 14569 19 | 3 7 8 | 456 15 2 |
| 356 356 8 | 4 1 2 | 567 357 9 |
| 2 134 7 | 6 9 5 | (48) 138 34 |
+------------------+-----------+-------------------+ |
(4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r3c7; r3c7 <> 4
-----
single stepper from marty's posted grid
| Quote: | | (4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r4c8 - (9=6)r4c6 - (6)r4c2 = (6)r5c3 - (6=9)r2c3 - (9)r2c78 = (9)r3c7; r3c7 <> 4 |
Last edited by storm_norm on Thu Feb 18, 2010 2:33 am; edited 1 time in total |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Feb 18, 2010 2:26 am Post subject: |
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| storm_norm wrote: | Keith,
just fyi,
there isn't a need to see the w-wing connected by the 6's...
since your extended w-wing 6,9 in your first grid is a loop, then the 9's in row 2 are eliminated in that step as well. |
And vice-versa? The other extended wing is also a loop, eliminating the 6's?
Keith |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Feb 18, 2010 2:34 am Post subject: |
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yes, they both do the same thing.
actually,
its the same chain... the only difference is that you are "cutting" the loop between different nodes in order to "see" it as two separate w-wings.
| Code: | lets number the nodes
#1 --> (6=9) r2c3
#2 --> (9) r2c8
#3 --> (9) r4c8
#4 --> (9=6) r4c6
#5 --> (6) r4c2
#6 --> (6) r5c3
w-wing {6,9} strong link on 9... extended via the 6's
(6=9)r2c3 - (9)r2c8 = (9)r4c8 - (9=6)r4c6 - (6)r4c2 = (6)r5c3
| | | | | |
1 2 3 4 5 6
w-wing {9,6} via strong link on 6, extended via the 9's
(9)r2c8 = (9)r4c8 - (9=6)r4c6 - (6)r4c2 = (6)r5c3 - (6=9)r2c3
| | | | | |
2 3 4 5 6 1 |
Last edited by storm_norm on Thu Feb 18, 2010 3:53 am; edited 4 times in total |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Feb 18, 2010 2:42 am Post subject: |
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Here is an ALS and a slightly different chain each of which solve the puzzle.
| Code: | +-----------------+---------+--------------+
| 357 8 2 | 9 6 4 | 1 b37 35 |
| 4567 4569 69 | 1 2 3 | 4789 789 456 |
| 346 13469 1369 | 5 8 7 |a49 2 346 |
+-----------------+---------+--------------+
| 8 36 4 | 7 35 69 | 2 -59 1 |
| 1 2 36 | 8 35 69 |a59 4 7 |
| 9 7 5 | 2 4 1 | 3 6 8 |
+-----------------+---------+--------------+
| 456 14569 169 | 3 7 8 | 4-56b15 2 |
| 356 356 8 | 4 1 2 |-567 b357 9 |
| 2 134 7 | 6 9 5 |a48 b138 34 |
+-----------------+---------+--------------+
ALS
a 4589
b 13578
x 8
z 5
AIC
(9)r4c8 = (9-8)r2c8 = r2c7 - (8=4)r9c7 - (4=9)r3c7 - r5c7 = r5c6;
r4c6,r5c7<>9
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Feb 18, 2010 3:39 am Post subject: |
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| storm_norm wrote: | leaves this chain...
(4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r3c7; r3c7 <> 4
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That chain cracks Marty's original grid. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Feb 18, 2010 5:54 am Post subject: |
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| daj95376 wrote: | | storm_norm wrote: | leaves this chain...
(4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r3c7; r3c7 <> 4
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That chain cracks Marty's original grid. |
Sometimes I can follow these notations, but this is a time when I can't. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Feb 18, 2010 7:25 am Post subject: |
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| Marty R. wrote: | | daj95376 wrote: | | storm_norm wrote: | leaves this chain...
(4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r3c7; r3c7 <> 4
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That chain cracks Marty's original grid. |
Sometimes I can follow these notations, but this is a time when I can't. |
The (traditional/condensed) Eureka notation for a
| Code: | gM-Wing: (Y=X)a - (X)b = (X-Y)r = (Y)s
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can be expanded to better show the three strong links -- "f", "g", and "h":
| Code: | ffffff ggggggggggg hhhhhhhhhhh
gM-Wing: (Y=X)a - (X)b = (X)r - (Y)r = (Y)s
| same cell | *** normally condensed
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So, for Norm's chain:
| Code: | (4=8)r9c7 - (8)r2c7 = (8-9)r2c8 = (9)r3c7; r3c7 <> 4
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we get:
| Code: | fffffffff ggggggggggggggggg hhhhhhhhhhhhhhhhh
(4=8)r9c7 - (8)r2c7 = (8)r2c8 - (9)r2c8 = (9)r3c7; r3c7 <> 4
| -- same cell -- |
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The final deduction for this AIC follows from forcing chain logic:
| Code: | r9c7=4 => r3c7<>4
r9c7<>4 => r3c7=9 => r3c7<>4
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Feb 18, 2010 2:40 pm Post subject: |
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Of a more general nature, there's my notes using Eureka Notation.
Note: [x] means cell "x", SL means strong link, and WL means weak link.
| Code: | ===== ===== ===== Basic Chain Terminology and Eureka Notation ===== ===== =====
Strong Inference (SI): ~A => B
Weak Inference (WI): A => ~B
(SI) e.g.: ( bilocation (n)a = (n)b ) or ( bivalue cell (m=n)c )
(WI) e.g.: ( peers (n)d - (n)e ) or ( ?-value cell (m-n)f )
bilocation (n)a = (n)b: if [a] is not 'n', then [b] is 'n'
bivalue cell (m=n)c : if [c] is not 'm', then [c] is 'n'
peers (n)d - (n)e: if [d] is 'n', then [e] is not 'n'
?-value cell (m-n)f : if [f] is 'm', then [f] is not 'n'
Sudopedia: a SL can be used for SI or WI, but a WL can only be used for WI
Myth Jellies' SI-based Alternating Inference Chain (AIC): ( SI WI ) ... SI
-- if the endpoints are the same cell & candidate, a discontinuous AIC loop
-- if a WI can connect the same cell & candidate, a continuous AIC loop
WI-based Alternating Inference Chain (AIC): ( WI SI ) ... WI
(used by ronk and Asellus)
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