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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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 Posted: Mon Sep 01, 2008 1:01 am Post subject: Sep 1 Spring Surprise |
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It's the first day of spring on this side of the world. The sun is warm, we're feeling good.
And, I've just solved a VH puzzle with box-line eliminations only. No wings necessary. Was the puzzle wrongly graded or did I stumble upon the solution by mistake?
Cheers |
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wapati
Joined: 10 Jun 2008
Posts: 472
Location: Brampton, Ontario, Canada.
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| Posted: Mon Sep 01, 2008 1:49 am Post subject: Re: Sep 1 Spring Surprise |
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| kragzy wrote: | It's the first day of spring on this side of the world. The sun is warm, we're feeling good.
And, I've just solved a VH puzzle with box-line eliminations only. No wings necessary. Was the puzzle wrongly graded or did I stumble upon the solution by mistake?
Cheers |
If you want a fast answer you must show the puzzle.
Some people must wait 24 hours to see it. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Sep 01, 2008 3:59 am Post subject: |
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| I used one hidden UR. It's possible to solve a puzzle with basics that others need advanced solutions for. I've done it, I guess it depends in large part on the sequence in which one does things. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Mon Sep 01, 2008 5:54 am Post subject: |
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Days start to feel like autumn here.
"Very hard" definitely solved by basics alone. (singles, naked pairs, not even a triple, box/line only once for that upper left box)
Time for a vacation in the sun. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon Sep 01, 2008 12:17 pm Post subject: |
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It’s Labour Day here in Canada – the beer stores are closed and the summer is over. And that was a Medium at most. All so very sad.  |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Sep 01, 2008 4:00 pm Post subject: |
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Withdrawn!
Last edited by daj95376 on Mon Sep 01, 2008 4:25 pm; edited 1 time in total |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Sep 01, 2008 4:03 pm Post subject: |
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| Code: |
+--------------+--------+-------------+
| 1359 13 38 | 2 6 7 | 389 4 3589 |
| 45 24 248 | 1 9 3 | 68 56 7 |
| 379 6 37 | 5 8 4 | 1 2 39 |
+--------------+--------+-------------+
| 8 235 235 | 4 23 1 | 7 9 6 |
| 14 124 9 | 6 7 8 | 5 3 24 |
| 34 7 6 | 9 23 5 | 24 8 1 |
+--------------+--------+-------------+
| 36 8 1 | 7 4 9 | 236 56 235 |
| 2 45 45 | 3 1 6 | 89 7 89 |
| 367 9 37 | 8 5 2 | 346 1 34 |
+--------------+--------+-------------+
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Play this puzzle online at the Daily Sudoku site
Just as a point of potential interest. This is where I am after basics. As noted above, I solved the puzzle with the hidden UR on 89 in boxes 39.
However, there is a potential DP on 24-25-45 in boxes 147. R2c3 must be = 8 or r4c2or r4c3 must be = 3 to kill the DP. Either way, r4c5 must be = 2 and that also solves the puzzle. |
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A.J.
Joined: 21 Mar 2008
Posts: 5
Location: San Diego, CA
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| Posted: Mon Sep 01, 2008 4:42 pm Post subject: |
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Code:
+--------------+--------+-------------+
| 1359 13 38 | 2 6 7 | 389 4 3589 |
| 45 24 248 | 1 9 3 | 68 56 7 |
| 379 6 37 | 5 8 4 | 1 2 39 |
+--------------+--------+-------------+
| 8 235 235 | 4 23 1 | 7 9 6 |
| 14 124 9 | 6 7 8 | 5 3 24 |
| 34 7 6 | 9 23 5 | 24 8 1 |
+--------------+--------+-------------+
| 36 8 1 | 7 4 9 | 236 56 235 |
| 2 45 45 | 3 1 6 | 89 7 89 |
| 367 9 37 | 8 5 2 | 346 1 34 |
+--------------+--------+-------------+
The naked pair 37 in column 3 eliminates the 3 in R1, C3 and it falls apart from their. No advanced techniques required.  |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Mon Sep 01, 2008 4:44 pm Post subject: |
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| Marty R. wrote: | | Code: |
+--------------+--------+-------------+
| 1359 13 38 | 2 6 7 | 389 4 3589 |
| 45 24 248 | 1 9 3 | 68 56 7 |
| 379 6 37 | 5 8 4 | 1 2 39 |
+--------------+--------+-------------+
| 8 235 235 | 4 23 1 | 7 9 6 |
| 14 124 9 | 6 7 8 | 5 3 24 |
| 34 7 6 | 9 23 5 | 24 8 1 |
+--------------+--------+-------------+
| 36 8 1 | 7 4 9 | 236 56 235 |
| 2 45 45 | 3 1 6 | 89 7 89 |
| 367 9 37 | 8 5 2 | 346 1 34 |
+--------------+--------+-------------+
|
However, there is a potential DP on 24-25-45 in boxes 147. R2c3 must be = 8 or r4c2or r4c3 must be = 3 to kill the DP. Either way, r4c5 must be = 2 and that also solves the puzzle. |
Marty, I never found the chain that forces r4c5=2 when r2c3=8, but noticed that the <37> pair in r39c3 forces the <8> deletion from r2c3 thereby making r4c5=2 to prevent the DP.
Ted |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Sep 01, 2008 5:51 pm Post subject: |
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| Quote: | | Marty, I never found the chain that forces r4c5=2 when r2c3=8, but noticed that the <37> pair in r39c3 forces the <8> deletion from r2c3 thereby making r4c5=2 to prevent the DP. |
Ted, if I did this thing correctly, the chain runs alphabetically from <a> to <h>. After <h> is solved for <2>, the <35> pair is exposed in that box, forcing r4c5 = <2>.
I did not use this DP in my solution, I just posted it for the benefit of anyone who might not be familiar with this type of DP.
| Code: | +--------------+--------+-------------------+
| 1359 13 38 | 2 6 7 | 389 4 3589 |
| 45 24 248a | 1 9 3 | 68b 56c 7 |
| 379 6 37 | 5 8 4 | 1 2 39 |
+--------------+--------+-------------------+
| 8 235 235 | 4 23 1 | 7 9 6 |
| 14g 124h 9 | 6 7 8 | 5 3 24 |
| 34f 7 6 | 9 23 5 | 24 8 1 |
+--------------+--------+-------------------+
| 36e 8 1 | 7 4 9 | 236 56d 235 |
| 2 45 45 | 3 1 6 | 89 7 89 |
| 367 9 37 | 8 5 2 | 346 1 34 |
+--------------+--------+-------------------+ |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon Sep 01, 2008 8:50 pm Post subject: |
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Marty: Maybe I'm missing something here but why not follow the trail from b=8 and not 6. Why not go to the <13> at R1C2 and follow the chains for <3> (which soon leads to oblivion). I am not convinced this is anything more than Trial and Error - which should not be sanctioned by sophisticates - like what we is.
Cheers |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Mon Sep 01, 2008 9:11 pm Post subject: |
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| cgordon wrote: | Marty: Maybe I'm missing something here but why not follow the trail from b=8 and not 6. Why not go to the <13> at R1C2 and follow the chains for <3> (which soon leads to oblivion). I am not convinced this is anything more than Trial and Error - which should not be sanctioned by sophisticates - like what we is.
Cheers |
Craig,
About all you're missing here is that I is not no sophisticate, whatever dat means. 
I agree that it has an element of trial-and-error. However, a number of people here accept the fact that a forcing chain (which I believe this to be) has some legitimacy when recognition of a pattern leads to it, as opposed to the examples you mention, which are just random.
The same principle seems to apply to other situations, such as BUG+2 or 3, a Type 3 UR, a so-called Finned XY-Wing and others. I'm not 100% comfortable with these things, but they do seem to have a little more cachet than random chains. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon Sep 01, 2008 9:41 pm Post subject: |
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Marty: I can see how a pattern could lead to a logical reduction or chain - but it's this bit I don't understand | Quote: | | However, there is a potential DP on 24-25-45 in boxes 147. |
To my limited understanding a DP is associated with a UR and a rectangular pattern. I just don't see that here?
Craig |
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Wendy W
Joined: 04 Feb 2008
Posts: 144
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| Posted: Mon Sep 01, 2008 11:02 pm Post subject: |
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| Just adding my 2 cents here -- I agree with everybody that this was an EZ one today, not even an xy wing required. But I find that reassuring, given that I have just reached a significant birthday milestone. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Tue Sep 02, 2008 12:24 am Post subject: |
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| cgordon wrote: | Marty: I can see how a pattern could lead to a logical reduction or chain - but it's this bit I don't understand | Quote: | | However, there is a potential DP on 24-25-45 in boxes 147. |
To my limited understanding a DP is associated with a UR and a rectangular pattern. I just don't see that here?
Craig |
Not necessarily. The BUG+1 (or 2 or 3) involves a DP as well. In this case, if the six cells were 24-24-25-25-45-45 there would be interchangeability, thus resulting in non-unique solutions. |
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kragzy
Joined: 01 May 2007
Posts: 112
Location: Australia
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| Posted: Tue Sep 02, 2008 4:29 am Post subject: |
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| Happy x0th birthday Wendy. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Tue Sep 02, 2008 7:20 pm Post subject: |
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| Quote: | | Not necessarily. The BUG+1 (or 2 or 3) involves a DP as well. In this case, if the six cells were 24-24-25-25-45-45 there would be interchangeability, thus resulting in non-unique solutions. |
There's only one thing I understood in the the last ten posts. Happy Birthday Wendy ! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Thu Sep 04, 2008 6:55 am Post subject: |
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| Wendy W wrote: | | Just adding my 2 cents here -- I agree with everybody that this was an EZ one today, not even an xy wing required. But I find that reassuring, given that I have just reached a significant birthday milestone. |
I am guessing 40
my second guess is 50 |
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