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daj95376
Joined: 23 Aug 2008
Posts: 3854
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 Posted: Sun Apr 11, 2010 2:04 pm Post subject: Puzzle 10/04/11 (C) |
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| Code: | +-----------------------+
| . 7 5 | . 9 . | . . . |
| 9 1 6 | . . 2 | . . 4 |
| 8 2 4 | . 1 . | 9 5 7 |
|-------+-------+-------|
| . . . | 5 . . | . 9 . |
| 5 . 8 | . . . | 2 . . |
| . 9 . | . . . | . 4 . |
|-------+-------+-------|
| . . 2 | . 7 . | 1 . . |
| . . 9 | 8 . 4 | . 7 . |
| . 8 7 | . . . | . . . |
+-----------------------+
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Play this puzzle online at the Daily Sudoku site
No cheating to get r1c1  |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Mon Apr 12, 2010 11:08 am Post subject: |
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After doing your last one (10/04/10 - chain) Danny, I went straight down to the bottom end of this one just in case.......
Another contradiction but this chain turns back on itself:
| Quote: | Really need one of Norm's diagrams:
When you put a 3 in r9c5 if true it creatres a locked pair <46> at r5c25.
This knocks out a 6 at r5c8 and this means r7c8 must be 6.
R7c4 can not be 6 so must be 3 and therefore r9c5 can not be 3! Contradiction.
(2=3)r9c5(3=6)[r5c25]-r5c8=r7c8-(6=3)r7c5-r9c5 so r9c5 <> 3
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Mon Apr 12, 2010 2:22 pm Post subject: |
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| Quote: | Type 2 UR13 deletes 6 in r3c6 to complete the puzzle.
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Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Apr 12, 2010 3:50 pm Post subject: |
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I used two Type 4 URs (59, 46) and a Type 1 (13).
| Quote: | | When you put a 3 in r9c5 if true it creatres a locked pair <46> at r5c25. |
There's no grid to look at, so what triggers you to put a 3 in r9c5? |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Mon Apr 12, 2010 4:43 pm Post subject: |
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| Marty R. wrote: | I used two Type 4 URs (59, 46) and a Type 1 (13).
| Quote: | | When you put a 3 in r9c5 if true it creatres a locked pair <46> at r5c25. |
There's no grid to look at, so what triggers you to put a 3 in r9c5? |
Let me remedy that and sincere apologies (forgive my grid) if you end up wishing you hadn't asked:
Sensate focus! You know when you buy say a blue Volvo and then you notice everyone is driving one ?
I had just completed Danny's other puzzle (10/04/10 ___ Chain) which involved the same cells r9c58 and a contradiction in my solution so I returned to the scene of the crime, alerted to the same type of thing.
As Dan has so ably demonstrated, there can be rich pickings on bivalues when you go chain hunting.
There were 2 bivalues lurking at the bottom and looking up I saw the potential for a naked pair (in blue) if 3 were true (I have learned ftom looking at Norm's diagrams to examine potentials) .
So we have bi values and then for helping in the construction of the AIC there were more strong links (in green, on 6) and being visual these jumped out at me. Now sometimes you construct a chain and it is unproductive but not this time. |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Mon Apr 12, 2010 5:22 pm Post subject: |
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| You can tell I was into chain mode as I missed the much simpler, cleaner one stepper UR on 13 which is also screaming out after basics as well. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Apr 12, 2010 6:14 pm Post subject: |
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There are several URs showing, including the <59> UR Type 1. However, let's stick with Mogulmeister's chain. For me, the key is the strong link in [c8] for <6> that lets r5c25=3+46 be joined to r7c4=36.
| Code: | (3=46)r5c25 - (6)r5c8 = (6)r7c8 - (6=3)r7c4 => r9c5<>3
*--------------------------------------------------------------------*
| 3 7 5 | 4 9 8 | 6 12 12 |
| 9 1 6 | 7 5 2 | 38 38 4 |
| 8 2 4 | 36 1 36 | 9 5 7 |
|----------------------+----------------------+----------------------|
| 2 46 13 | 5 3468 136 | 7 9 368 |
| 5 46 8 | 9 346 7 | 2 136 136 |
| 7 9 13 | 2 368 136 | 358 4 3568 |
|----------------------+----------------------+----------------------|
| 4 35 2 | 36 7 59 | 1 368 35689 |
| 1 35 9 | 8 26 4 | 35 7 26 |
| 6 8 7 | 1 23 59 | 4 23 59 |
*--------------------------------------------------------------------*
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Apr 12, 2010 6:32 pm Post subject: |
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| Quote: | As Dan has so ably demonstrated, there can be rich pickings on bivalues when you go chain hunting.
There were 2 bivalues lurking at the bottom and looking up I saw the potential for a naked pair (in blue) if 3 were true (I have learned ftom looking at Norm's diagrams to examine potentials) . |
I think essentially your answer is the same as when the guy is asked why he climbs Mt. Everest. "Because it's there." |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Mon Apr 12, 2010 7:25 pm Post subject: |
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...and in the case of this puzzle a little sense that I have been a bit like NASA designing a pen that pumps ink to the tip in zero gravity and the Russians just use a pencil !  |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Apr 12, 2010 7:51 pm Post subject: |
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| Mogulmeister wrote: | | ...and in the case of this puzzle a little sense that I have been a bit like NASA designing a pen that pumps ink to the tip in zero gravity and the Russians just use a pencil ! |
Yes, but they probably bought several gross of Pentel pencils ... USA.
I divide my "writing life" into Before Pentel (BP) and After Pentel (AP).
I use a Pentel 0.5mm w/HB lead (and the great eraser) whenever possible. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Apr 12, 2010 8:49 pm Post subject: |
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| Quote: | | I use a Pentel 0.5mm w/HB lead (and the great eraser) whenever possible. |
I use a pencil with .7mm HB lead.
Pentel retractable erasers are used for most normal erasing during the course of working a puzzle.
I also use a Paper Mate retractable eraser with a much smaller diameter when I have to erase a candidate from a cell with so many candidates that the Pentel is too large.
And a classic Pink Pearl to erase the whole grid when I'm close to finishing a puzzle and the dreaded duplicate number rears its ugly head, an occurrence which happens all too often.
Blank grids for testing chains, coloring, or whatever.
And finally, a clipboard so I can do puzzles while sitting comfortably on the couch.
And that's my complete equipment inventory!! |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Apr 13, 2010 6:17 am Post subject: |
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The Paper Mate is definitely high tech!  |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Tue Apr 13, 2010 2:31 pm Post subject: |
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The image of marty on the couch with his finely tuned tools is in sharp contrast to my occasional 'rough terrain sudoku'. Ink pen, standing on the Piccadilly underground line in the rush hour, Daily Telegraph Diabolical (mepham), directly on the newspaper - that makes for a real challenge!! The grid ends up looking like the Somme!
(anything more than an x-wing or some simple kite/skyscraper moves and I have to wait till I get home... ) |
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Mogulmeister
Joined: 03 May 2007
Posts: 1151
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| Posted: Tue Apr 13, 2010 2:44 pm Post subject: |
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I wonder if the Ipad or similar will be the answer to the off-piste sudokuist's prayer ?
Like you Peter, my peripatetic scratchings on newspapers just gets horrible. Sudoku on the Blackberry is farcical (too small, too easy) and it is not practical to open up the laptop on the underground.
Someone should invent a folding gizmo that opens out to the size of A4 say, but has a touch screen and can be web linked. |
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