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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Wed Jun 24, 2009 3:51 pm Post subject: Puzzle NR_047 |
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I'm going to post easier puzzles for awhile.
| Code: | +-----------------------+
| . 5 . | . . . | 6 . . |
| 7 . . | 9 3 . | . . . |
| . . 6 | 5 . 8 | . 7 9 |
|-------+-------+-------|
| . 4 7 | . 8 1 | . 9 . |
| . 8 . | 2 . . | . 6 3 |
| . . 3 | 6 . . | . . . |
|-------+-------+-------|
| 9 . . | . . . | 8 . . |
| . . 5 | 8 7 . | . 4 . |
| . . 8 | . 6 . | . . 7 |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
| Code: | r4 b6 Locked Pair <> 25 [r6c789]
c4b8 Locked Pair <> 14 [r7c5],[r9c6]
b9 Naked Triple <> 125 [r89c7]
c8b9 Locked Candidate 1 <> 5 [r2c8]
XYZ-Wing [r9c1]/[r8c1]+[r9c4] <> 1 [r9c2]
c1b7 Locked Candidate 1 <> 1 [r3c1]
XY-Wing [r8c1]/[r8c9]+[r9c2] <> 2 [r9c8]
c38 X-Wing <> 2 [r2c279],[r7c5]
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Last edited by daj95376 on Sat Jul 04, 2009 4:03 pm; edited 1 time in total |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Wed Jun 24, 2009 9:33 pm Post subject: |
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A one step solution if my analysis is correct.
Looking at the UR 47 in r56c67, we see that r6c6=5 or r6c7=1 is required to insure uniqueness.
1) Verbally: if r6c6=5 then r9c6<>5 then r7c5=5; Notation: (5)r6c6 - (5)r9c6 = (5)r7c5;
2) Verbally: if r6c7=1 then r6c8=8 then r2c8=12 to form a <12> subset with r2c2 to delete 2 from r2c3 so that r2c3=4 then r7c3=2 then r7c5=5. Notation: (1)r6c7 - (1=8)r6c8 - (8=12)r2c8 - [SS(12)r2c18 = (4)r2c3] - (4=2)r7c3 - (2=5)r7c5.
Both conditions force r7c5=5 and solve the puzzle.
Ted
p.s. I know my notation to handle the subset is questionable, but I hope the logic is valid. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Thu Jun 25, 2009 12:49 am Post subject: |
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Ted, your logic seems fine to me. I'll let someone else provide notation for your SS exchange. I've seen it written different ways and don't want to get into the middle of a discussion on what's right.
You also exposed a great UR chain/net.
(5=2)r7c5 - (2=4)r7c3 - (4=2)r2c3 - (2=1)r2c2 - (1=8)r2c8 - (8=1)r6c8 - UR47[(1)r6c7 = (5)r6c6]; => [r6c5],[r9c6]<>5
| Code: | +-----------------------------------------------------------------------+
| 8 5 9 | 7 124 24 | 6 3 124 |
| 7 12 24 | 9 3 6 | 1245 128 12458 |
| 134 123 6 | 5 124 8 | 124 7 9 |
|-----------------------+-----------------------+-----------------------|
| 6 4 7 | 3 8 1 | 25 9 25 |
| 5 8 1 | 2 9 47 | 47 6 3 |
| 2 9 3 | 6 45 457 | 147 18 148 |
|-----------------------+-----------------------+-----------------------|
| 9 7 24 | 14 25 3 | 8 125 6 |
| 13 6 5 | 8 7 29 | 39 4 12 |
| 134 123 8 | 14 6 259 | 39 125 7 |
+-----------------------------------------------------------------------+
# 55 eliminations remain
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Note: A UR chain/net is allowed to have a memory of previous eliminations in a cell. Thus, - (1=8)r2c8 is a valid deduction because (4=2)r2c3 eliminated <2> earlier in [r2c8]. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jun 25, 2009 6:04 pm Post subject: |
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| Code: | .---------------------.---------------------.---------------------.
| 8 5 9 | 7 124 24 | 6 3 124 |
| 7 12 24 | 9 3 6 | 1245 128 12458 |
| 134 123 6 | 5 124 8 | 124 7 9 |
:---------------------+---------------------+---------------------:
| 6 4 7 | 3 8 1 | 25 9 25 |
| 5 8 1 | 2 9 47 | 47 6 3 |
| 2 9 3 | 6 45 457 | 147 18 148 |
:---------------------+---------------------+---------------------:
| 9 7 24 | 14 25 3 | 8 125 6 |
| 13 6 5 | 8 7 29 | 39 4 12 |
| 134 123 8 | 14 6 259 | 39 125 7 |
'---------------------'---------------------'---------------------' |
this might resolve the memory issue and be a tad bit cleaner and might be exactly what Ted saw.
np= naked pair
UR47[(5)r6c6 = (1)r6c7] - (1=8)r6c8 - (8)r2c8 = (np12)r2c28 - (2=4)r2c3 - (4=2)r7c3 - (2=5)r7c5; r6c5 <> 5
its kind of what Danny posted only reversed and with a naked pair, instead of the memory. |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Thu Jun 25, 2009 11:19 pm Post subject: |
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| storm_norm wrote: | | Code: | .---------------------.---------------------.---------------------.
| 8 5 9 | 7 124 24 | 6 3 124 |
| 7 12 24 | 9 3 6 | 1245 128 12458 |
| 134 123 6 | 5 124 8 | 124 7 9 |
:---------------------+---------------------+---------------------:
| 6 4 7 | 3 8 1 | 25 9 25 |
| 5 8 1 | 2 9 47 | 47 6 3 |
| 2 9 3 | 6 45 457 | 147 18 148 |
:---------------------+---------------------+---------------------:
| 9 7 24 | 14 25 3 | 8 125 6 |
| 13 6 5 | 8 7 29 | 39 4 12 |
| 134 123 8 | 14 6 259 | 39 125 7 |
'---------------------'---------------------'---------------------' |
this might resolve the memory issue and be a tad bit cleaner and might be exactly what Ted saw.
np= naked pair
UR47[(5)r6c6 = (1)r6c7] - (1=8)r6c8 - (8)r2c8 = (np12)r2c28 - (2=4)r2c3 - (4=2)r7c3 - (2=5)r7c5; r6c5 <> 5
its kind of what Danny posted only reversed and with a naked pair, instead of the memory. |
Norm, I like your notational use of a "hidden pain" better than my attempt.
Ted |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Jun 25, 2009 11:33 pm Post subject: |
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Ted,
thank you, and it was a very nice find on your part. I liked the use of the naked pair 12 |
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