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garytorborg
Joined: 19 Jan 2011
Posts: 28
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 Posted: Wed Mar 23, 2011 9:43 pm Post subject: More UR goodies? |
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Hmmm. I'm stuck in a puzzle that I suspect has some more of those hidden URs like the last one. Can anyone help?
| Code: |
+--------------+--------------+---------------+
| 89 89 5 | 167 167 2 | 3 146 467 |
| 3 4 167 | 8 167 9 | 17 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
+--------------+--------------+---------------+
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 59 |
| 4 179 2 | 167 1679 156 | 59 8 3 |
+--------------+--------------+---------------+
| 158 2 9 | 146 3 7 | 15 146 4568 |
| 6 3 17 | 5 124 8 | 1279 14 479 |
| 1578 178 4 | 9 126 16 | 1257 3 5678 |
+--------------+--------------+---------------+
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Play this puzzle online at the Daily Sudoku site
All those "167s" have to mean something... |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Wed Mar 23, 2011 10:50 pm Post subject: |
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Look at R3. You can eliminate 1 in R2C3.
Otherwise, I don't see anything.
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Mar 24, 2011 12:22 am Post subject: Re: More UR goodies? |
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| garytorborg wrote: | Hmmm. I'm stuck in a puzzle that I suspect has some more of those hidden URs like the last one. Can anyone help?
| Code: |
+--------------+--------------+---------------+
| 89 89 5 | 167 167 2 | 3 146 467 |
| 3 4 167 | 8 167 9 | 17 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
+--------------+--------------+---------------+
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 59 |
| 4 179 2 | 167 1679 156 | 59 8 3 |
+--------------+--------------+---------------+
| 158 2 9 | 146 3 7 | 15 146 4568 |
| 6 3 17 | 5 124 8 | 1279 14 479 |
| 1578 178 4 | 9 126 16 | 1257 3 5678 |
+--------------+--------------+---------------+
|
Play this puzzle online at the Daily Sudoku site
All those "167s" have to mean something... |
You can play with the potential 58 UR in boxes 79. R79c1 must be 1 or 7. This pseudo cell combines with r8c3 to force r9c2<>17. R79c9 must be 4,6 or7. This combines with r13c9 to form a 467 pseudo cell, forcing r8c9<>47. Under both scenarios, r1c12=89 and r9c2=8, bringing us here, where I still don't see anything.
| Code: |
+-------------+--------------+--------------+
| 8 9 5 | 167 167 2 | 3 146 467 |
| 3 4 167 | 8 167 9 | 17 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
+-------------+--------------+--------------+
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 59 |
| 4 179 2 | 167 1679 156 | 59 8 3 |
+-------------+--------------+--------------+
| 15 2 9 | 46 3 7 | 15 46 8 |
| 6 3 17 | 5 124 8 | 1279 14 479 |
| 157 8 4 | 9 126 16 | 1257 3 567 |
+-------------+--------------+--------------+
|
Play this puzzle online at the Daily Sudoku site |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Thu Mar 24, 2011 1:39 am Post subject: |
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Marty, R6C2 is not 9. Also, look at R3. R2C3 is not 1.Which gets us here: | Code: | +----------------+----------------+----------------+
| 8 9 5 | 167 167 2 | 3 146 467 |
| 3 4 6-7 | 8 167 9 | 17# 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
+----------------+----------------+----------------+
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 59 |
| 4 17 2 | 167 1679 156 | 59 8 3 |
+----------------+----------------+----------------+
| 15@ 2 9 | 46 3 7 | 15@ 46 8 |
| 6 3 17# | 5 124 8 | 1279 14 479 |
| 157 8 4 | 9 126 16 | 1257 3 567 |
+----------------+----------------+----------------+ |
The W-wing solves it.
Keith |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Thu Mar 24, 2011 7:56 am Post subject: |
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Forgoing DPs, I used the otherwise useless 15 W-Wing in r5c6|r7c7 with transports:
(1)r5c6-(1=6)r9c6 and (1)r7c7-ALS[(1)r78c8=(6)r7c8]; r9c9<>6
(Alternately, that second transport can be a short XY-Chain via box 3 to <6> in r3c9.)
After simplification (no <6> in r7c4), repeat with different transports:
(1)r5c6-(1=9)r5c1 and (1)r7c7-(1=4)r7c4-(4=7)r4c4-(7=9)r4c1; r1c1<>9
That solves the puzzle. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Mar 25, 2011 2:04 am Post subject: |
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Okay, since Ted doesn't seem interested, here's a UR step that helps:
| Code: | <58> UR r79c19 w/external SIS r1c1=8 and/or r5c9=5
(8=9)r1c1 - (9=1)r5c1 - (1=5)r5c6 - UR[(5)r5c9 = (8)r1c1] => r1c1=8
+--------------------------------------------------------------+
| #89 89 5 | 167 167 2 | 3 146 467 |
| 3 4 167 | 8 167 9 | 17 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
|--------------------+--------------------+--------------------|
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 #59 |
| 4 179 2 | 167 1679 156 | 59 8 3 |
|--------------------+--------------------+--------------------|
| *58+1 2 9 | 146 3 7 | 15 146 *58+46 |
| 6 3 17 | 5 124 8 | 1279 14 479 |
| *58+17 178 4 | 9 126 16 | 1257 3 *58+67 |
+--------------------------------------------------------------+
# 69 eliminations remain
r7 Naked Pair <> 15 r7c48
r3 b1 Locked Candidate 2 <> 1 r2c3
c2348 Jellyfish (2222) <> 1 r1c5,r6c56,r8c57 -or-
r2579 Jellyfish (2224) <> 1 r1c5,r6c56,r8c57
r9 b8 Locked Candidate 1 <> 1 r9c17
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| Code: | +-----------------------------------------------------+
| 8 9 5 | 167 67 2 | 3 146 467 |
| 3 4 67 | 8 167 9 | 17 5 2 |
| 2 17 167 | 3 5 4 | 8 9 67 |
|-----------------+-----------------+-----------------|
| 79 5 8 | 47 479 3 | 6 2 1 |
| 19 6 3 | 2 8 15 | 4 7 59 |
| 4 17 2 | 167 679 56 | 59 8 3 |
|-----------------+-----------------+-----------------|
| 15 2 9 | 46 3 7 | 15 46 8 |
| 6 3 17 | 5 24 8 | 279 14 479 |
| 57 8 4 | 9 126 16 | 257 3 567 |
+-----------------------------------------------------+
# 48 eliminations remain
W-Wing: (7=1)r2c7 - r1c8 = r8c8 - (1=7)r8c3 => r2c3,r8c7<>7 -or-
W-Wing: (7=1)r2c7 - r7c7 = r7c1 - (1=7)r8c3 => r2c3,r8c7<>7 -or-
W-Wing: (7=1)r2c7 - r7c7 = r8c8 - (1=7)r8c3 => r2c3,r8c7<>7
-or-
XY-Chain: (7=1)r2c7 =5r7c7 =1r7c1 =7r8c3 => r2c3,r8c7<>7
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Fri Mar 25, 2011 10:27 am Post subject: |
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| daj95376 wrote: | ... here's a UR step that helps:
| Code: | <58> UR r79c19 w/external SIS r1c1=8 and/or r5c9=5
(8=9)r1c1 - (9=1)r5c1 - (1=5)r5c6 - UR[(5)r5c9 = (8)r1c1] => r1c1=8 |
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There seems to be a growing tendency to write expressions that result in placements, and I don't understand why. Isn't r1c1<>9 the underlying move here, a move which would still be true even if r1c1 had three or more candidates?
(9)r5c1 = (9)r5c9 - UR[(5)r5c9 = (8)r1c1] => r1c1<>9 |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Fri Mar 25, 2011 5:43 pm Post subject: |
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| ronk wrote: | There seems to be a growing tendency to write expressions that result in placements, and I don't understand why. Isn't r1c1<>9 the underlying move here, ...?
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Yes, you caught me making the same mistake that I dislike seeing others make. My only excuse is that I was tired from spending the whole day moving furniture so the cleaning lady could get to places that haven't seen sunlight in years. Today, I finish move it all back. Oh Joy!!! |
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Fri Mar 25, 2011 6:19 pm Post subject: |
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For those who don't see the distinction, using a UR to set one cell doesn't always get all the eliminations. If you use the UR to remove all the candidates indicated you may well shorten your solving path. Geez, I'm agreeing with ronk!  |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat Mar 26, 2011 12:49 pm Post subject: |
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Another perspective of dealing with AURs, is that of using various combinations of strong inferences; each set has the potential of providing different deletions.
Ted |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat Mar 26, 2011 2:30 pm Post subject: |
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Been away for a while and just had the opportunity to review the details of these earlier posts. The one by Danny using an external strong inference set was short and effective; what more could you want. However, I really liked the technique used by Marty; I think it generally had less probability of success but he made it happen!
The great flexibility offered by ADPs is a major attraction to me.
Ted |
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