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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Tue Apr 20, 2010 11:09 pm Post subject: Puzzle 10/04/20 (D) ___ Advanced |
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By special request ... and he doesn't even know it.
| Code: | +-----------------------+
| 7 . 4 | 6 . . | . . . |
| . . 2 | . . 7 | . . 9 |
| 9 3 . | . . 4 | . . 7 |
|-------+-------+-------|
| 3 . . | . . . | . . 4 |
| . . . | . . 5 | . . . |
| . 1 7 | . 3 6 | . 5 8 |
|-------+-------+-------|
| . . . | . . . | 9 . . |
| . . . | . . 3 | . 7 5 |
| . 5 3 | 7 . 1 | . 4 6 |
+-----------------------+
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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 Apr 21, 2010 8:08 am Post subject: |
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| I now believe that my solution to this puzzle is inappropriate. If you like chains, then it may still prove interesting. |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Wed Apr 21, 2010 12:52 pm Post subject: |
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I like chains  | Quote: | | (8=7)r4c5-(7=6)r4c7-(6=5)r3c7-(5=8)r3c4; r23c5,r4c4<>8 |
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Wed Apr 21, 2010 12:58 pm Post subject: |
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This simplifies so far along that I assumed it was easy.
To finish I needed a very strange composite W-wing, both ends are made up.
The cells marked with # form a pair of 8s, one of which must to true.
The pair marked A form a 68 as does the pair marked B.
Because one of the #8s must be true one of the "made-up" 6s must be true.
| Code: | .---------------.---------------.---------------.
| 7 8 4 | 6 25 9 | 35 123 123 |
| 5 6 2 | 3 1 7 | 4 8 9 |
| 9 3 1 |A58 #258 4 |A56 2-6 7 |
:---------------+---------------+---------------:
| 3 9 5 |B18 #78 2 | 7-6 B16 4 |
| 6 2 8 | 14 47 5 | 37 9 13 |
| 4 1 7 | 9 3 6 | 2 5 8 |
:---------------+---------------+---------------:
| 1 7 6 | 45 45 8 | 9 23 23 |
| 8 4 9 | 2 6 3 | 1 7 5 |
| 2 5 3 | 7 9 1 | 8 4 6 |
'---------------'---------------'---------------' |
This is a strange puzzle! |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Apr 21, 2010 3:52 pm Post subject: |
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Wapati, if I ignore the (#) cells, then your AB pattern reminds me of an ALS -- of which I have little experience.
| Code: | A=r3c47=568 and B=r4c48=168
r3c8=6 => r3c7=5 => r3c4=8
=> r4c8=1 => r4c4=8
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Wed Apr 21, 2010 4:27 pm Post subject: |
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| daj95376 wrote: | Wapati, if I ignore the (#) cells, then your AB pattern reminds me of an ALS -- of which I have little experience.
| Code: | A=r3c47=568 and B=r4c48=168
r3c8=6 => r3c7=5 => r3c4=8
=> r4c8=1 => r4c4=8
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I have little ALS experience except simple line-box ones.
If I looked at just the AB sets I'd spot a Death Blossom.
I only find a few of these without help but this one is pretty simple. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Wed Apr 21, 2010 5:26 pm Post subject: |
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Here's the solution that caught my attention.
| Code: | after basics, there's a UR Type 2
+------------------------------------------------------+
| 7 8 4 | 6 25-1 9 | 35 *23+1 *23+1 |
| 5 6 2 | 3 18 7 | 4 8-1 9 |
| 9 3 1 | 58 258 4 | 56 268 7 |
|-----------------+-----------------+------------------|
| 3 9 5 | 18 78 2 | 67 16 4 |
| 6 2 8 | 14 47 5 | 37 9 13 |
| 4 1 7 | 9 3 6 | 2 5 8 |
|-----------------+-----------------+------------------|
| 1 7 6 | 45 45 8 | 9 *23 *23 |
| 8 4 9 | 2 6 3 | 1 7 5 |
| 2 5 3 | 7 9 1 | 8 4 6 |
+------------------------------------------------------+
# 27 eliminations remain
r17c89 <23> UR Type 2.2233 r1c5,r2c8<>1
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| Code: | however, strong-link eliminations also exist
leaving a BUG+1
+-----------------------------------------------------+
| 7 8 4 | 6 25 9 | 35 123 123 |
| 5 6 2 | 3 1 7 | 4 8 9 |
| 9 3 1 | 58 258 4 | 56 26 7 |
|-----------------+-----------------+-----------------|
| 3 9 5 | 18 78 2 | 67 16 4 |
| 6 2 8 | 14 47 5 | 37 9 13 |
| 4 1 7 | 9 3 6 | 2 5 8 |
|-----------------+-----------------+-----------------|
| 1 7 6 | 45 45 8 | 9 23 23 |
| 8 4 9 | 2 6 3 | 1 7 5 |
| 2 5 3 | 7 9 1 | 8 4 6 |
+-----------------------------------------------------+
# 23 eliminations remain
r17c89 <23> UR via s-link <> 3 r1c8 *** sufficient
r17c89 <23> UR via s-link <> 2 r1c9 *** sufficient
r17c89 <23> UR via s-link <> 2 r7c8
r17c89 <23> UR via s-link <> 3 r7c9
BUG+1 = 5 r3c5
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Wed Apr 21, 2010 11:03 pm Post subject: |
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| Like it. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Apr 22, 2010 5:28 pm Post subject: |
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| I used the Type 2 UR (23-1), an M-Wing (13) and BUG+1. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sun Apr 25, 2010 6:36 pm Post subject: |
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Still trying to handle assorted DPs such as the (hopefully) MUG128 in r123c58. Looking at thr outside row requirements, we see
Digit 1: (1)r1c9 - r2c8 = (1)r2c5,
Digit 2: (2-1)r1c9 = r5c9 - r5c4 = (1-8)r4c4 = r3c4 - (8=1)r2c5,
Digit 8: (8)r3c4 - (8=1)r2c5.
Thus, all constraints force r2c5=1.
(I thought it was a great move but it only solved two cells!)
UR23 in r17c89 with strong link 2 in r7 & c9; r1c8<>3
BUG+1 forces r3c5=5 to complete the puzzle.
Another FUN puzzle 
Ted |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sun Apr 25, 2010 6:55 pm Post subject: |
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| daj95376 wrote: | Wapati, if I ignore the (#) cells, then your AB pattern reminds me of an ALS -- of which I have little experience.
| Code: | A=r3c47=568 and B=r4c48=168
r3c8=6 => r3c7=5 => r3c4=8
=> r4c8=1 => r4c4=8
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To me, that is a wonderful one-step ALS solution.
ALS_A 568 in r 3c47
ALS_B 168 in r4c48
Shared Exclusive = 8,
Shared Common= 6
Thus, r3c8|r4c7<>6.
I believe the logic of the ALS is as follows:
The Shared Exclusive, 8, can only be true in one of the two ALSs; it must be weakly linked between then.
If ALS_A does not contain an 8, then r3c4=5 - (5=6)rr3c7; r3c8| r4c7<>6,
If ALS_B does not contain an 8, then r4c4=1 - (1=6)r4c8; r3c8| r4c7<>6
Ted |
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