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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Fri Dec 10, 2010 5:17 pm Post subject: Free Press Dec 10, 2010 |
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Not yet started ...
| Code: | Puzzle: FP121010
+-------+-------+-------+
| 8 . . | 3 2 1 | . 7 5 |
| . . 6 | 7 8 . | . . . |
| 3 . . | . . . | . . . |
+-------+-------+-------+
| . 6 1 | . . . | . . . |
| . 5 3 | . . . | 1 2 . |
| . . . | . . . | 7 5 . |
+-------+-------+-------+
| . . . | . . . | . . 7 |
| . . . | . 4 9 | 5 . . |
| 6 4 . | 1 7 5 | . . 9 |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Dec 10, 2010 8:26 pm Post subject: |
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I'm gun-shy lately, with good reason, but I'll take a chance and say:
| Quote: | | W-Wing (46); r5c45, r6c9<>6 |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Dec 10, 2010 8:38 pm Post subject: |
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After basics: | Code: | +----------------+----------------+----------------+
| 8 9 4 | 3 2 1 | 6 7 5 |
| 5 1 6 | 7 8 4 | 3 9 2 |
| 3 7 2 | 59 59 6 | 8 4 1 |
+----------------+----------------+----------------+
| 27 6 1 | 45 35 27 | 9 8 34 |
| 47 5 3 | 4689 69 78 | 1 2 46 |
| 24 8 9 | 46 1 23 | 7 5 346 |
+----------------+----------------+----------------+
| 9 2 5 | 68 36 38 | 4 1 7 |
| 1 3 7 | 2 4 9 | 5 6 8 |
| 6 4 8 | 1 7 5 | 2 3 9 |
+----------------+----------------+----------------+ |
| Quote: | Note the UR 46 in R56C49. R5C4 <>6.
Which is a BUG+2. R5C4 is 4 and / or R6C9 is 4. R6C4 = 6 solves it.
Actually, in the grid above, to break up the DP, either R5C4 is 46, which forces 4 in R6C1, or R6C9 is 4. Either way, R6C4 <> 4.
Or, looking further, a 4-6 W-wing solves it. |
I guess Marty posted his solution while I was composing mine!
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Dec 10, 2010 10:32 pm Post subject: |
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| Quote: | | Which is a BUG+2. R5C4 is 4 and / or R6C9 is 4. R6C4 = 6 solves it. |
Why isn't this treated like a BUG+3? Isn't 6 in r5c4 one of the potential killers? |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Fri Dec 10, 2010 11:45 pm Post subject: |
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| Marty R. wrote: | | Quote: | | Which is a BUG+2. R5C4 is 4 and / or R6C9 is 4. R6C4 = 6 solves it. |
Why isn't this treated like a BUG+3? Isn't 6 in r5c4 one of the potential killers? |
Marty,
You are correct. I had thought BUG+n means n cell have more than two candidates. I now see it means that there are n extra candidates in the puzzle.
Keith |
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tlanglet
Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
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| Posted: Sat Dec 11, 2010 12:15 am Post subject: |
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I used one of Keith's xy-wing with pseudocell pincer.
xy-wing 23-4 with vertex (23)r6c6 and pseudocell (34)r4c45; r6c4<>4=6
Ted |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Dec 11, 2010 3:30 am Post subject: |
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Ted,
I am flattered to be given credit.
There is another one in C45: 59 45 46 69 5-9
Every cell in the puzzle can be solved (or simplified) with an XY-chain, except perhaps R4C9.
Keith |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Sat Dec 11, 2010 9:44 pm Post subject: |
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| keith wrote: | | Marty R. wrote: | | Quote: | | Which is a BUG+2. R5C4 is 4 and / or R6C9 is 4. R6C4 = 6 solves it. |
Why isn't this treated like a BUG+3? Isn't 6 in r5c4 one of the potential killers? |
You are correct. I had thought BUG+n means n cell have more than two candidates. I now see it means that there are n extra candidates in the puzzle. |
keith, you were originally correct with BUG+2, and I see sudopedia has got it wrong. 
| sudopedia wrote: |
The term BUG+k is used to denote a BUG grid with k extra candidates. The simplest form is BUG+1, where the sole extra candidate can be immediately placed in its cell. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Dec 11, 2010 10:28 pm Post subject: |
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So what is the correct terminology when a cell has more than three candidates? Is is even necessary to note that the BUG+N has more than N extra candidates? I wasn't sure which is why I asked Keith the question in the way that I did.
"Why isn't this treated like a BUG+3?" |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Dec 11, 2010 10:35 pm Post subject: |
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Ron,
If BUG+n means n cells have any number of candidates more than two, I can go back to sleep.
(And, they have to fit the BUG elimination test of two candidates in each house.)
I am not aware of any theory surrounding any deadly pattern (DP) BUG pattern, other than they are a DP. Then, make ad hoc deductions.
In other words, do you see a reason to describe this pattern as a BUG+3 rather than a BUG+2? Or, vice-versa?
If not, I am with BUG+n means n cells with any number of extra candidates.
Keith |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Dec 12, 2010 1:00 am Post subject: |
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| Marty R. wrote: | So what is the correct terminology when a cell has more than three candidates? Is is even necessary to note that the BUG+N has more than N extra candidates? I wasn't sure which is why I asked Keith the question in the way that I did.
"Why isn't this treated like a BUG+3?" |
Marty,
We should wait for Ron's opinion, but I don't think it matters how many more than two candidates a BUG+ cell has.
If it has three candidates, the BUG buster is a single candidate. If it has four, the BUG buster is a pair, ...
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Dec 12, 2010 1:05 am Post subject: |
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| keith wrote: | | Marty R. wrote: | So what is the correct terminology when a cell has more than three candidates? Is is even necessary to note that the BUG+N has more than N extra candidates? I wasn't sure which is why I asked Keith the question in the way that I did.
"Why isn't this treated like a BUG+3?" |
Marty,
We should wait for Ron's opinion, but I don't think it matters how many more than two candidates a BUG+ cell has.
If it has three candidates, the BUG buster is a single candidate. If it has four, the BUG buster is a pair, ...
Keith |
Yes, I want to hear from Ron too. But from your point of view, if I posted my solution to a puzzle and it included a BUG+1:
Would you want to know if the cell contained four candidates?
Would you care?
Regardless of what it's called, the process is more like a BUG+2 than BUG+1 since the ramifications of two numbers have to be examined. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Dec 12, 2010 2:09 am Post subject: |
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Marty,
In my opinion, there is no theory here. We are talking about terminology and notation.
In a BUG pattern, if a cell contains more than two candidates, the BUG logic will potentially reduce it by two candidates. This is what I call a BUG buster.
If there is more than one cell that has a BUG buster, they are and / or. It does not matter what the candidates are. Go figure. Therefore, I think BUG+n should mean n cells, not n candidates, and not all candidates summed over all BUG cells.
Suppose we have:
One cell with an extra candidate <1>. BUG+1
One cell with two extra candidates <12>. BUG+1 in my book.
Two cells each with extra candidate <1>. BUG+2 in my book. (BUG + 1 in Marty's book?)
Two cells, one with extra candidate <1>, the other with extra candidate <2>. BUG+2 in my book, pseudocell <12>, go figure.
Two cells, one with extra candidate <1>, the other with extra candidates <23>. BUG+2 in my book, pseudocell <123>, go figure.
Keith |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sun Dec 12, 2010 2:15 am Post subject: |
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Consider the classic BUG+1 scenario of a single cell with three candidates.
| Code: | +-----------------------------------------------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
|---------------+---------------+---------------|
| . . . | . . . | . . . |
| . . . | . ST+Z . | . . . |
| . . . | . . . | . . . |
|---------------+---------------+---------------|
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+-----------------------------------------------+
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Here, the answer is r5c5<>S and r5c5<>T because r5c5=Z must be true to prevent a BUG.
Now, consider a BUG+1 scenario of a single cell with four candidates.
| Code: | +-----------------------------------------------+
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
|---------------+---------------+---------------|
| . . . | . . . | . . . |
| . . . | . ST+YZ . | . . . |
| . . . | . . . | . . . |
|---------------+---------------+---------------|
| . . . | . . . | . . . |
| . . . | . . . | . . . |
| . . . | . . . | . . . |
+-----------------------------------------------+
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Here, the answer is r5c5<>S and r5c5<>T because one of ( r5c5=Y or r5c5=Z ) must be true to prevent a BUG. We just don't know which answer is true.
I hope ronk's explanation covers these two scenarios! |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Sun Dec 12, 2010 5:50 am Post subject: |
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Gee guys, in the past I've not really considered the "why" of 'N' standing for the number of cells (instead of the number of extra candidates) in the "BUG+N" convention. That's just the way Jeff wrote the definition back in 2005 or 2006.
| Jeff wrote: |
A poly-valued cell for the purposes of this thread is a cell having more than two candidates.
...
A BUG+n is a BUG that has exactly n number of poly-valued cells. A BUG+1 is a BUG that has exactly one poly-valued cell left. |
But allow me to answer with a question. Let's say I'm looking at a pencilmark grid which you haven't yet seen. The pencilmarks have one poly-valued cell with five candidates, i.e., three extra candidates. Now, without you yet seeing the pencilmarks, I can describe my move as either BUG+1 or BUG+3. Which is more informative?
Sorry, but that's the best answer I've got at this hour. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Dec 12, 2010 5:50 am Post subject: |
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Keith, I agree that it's terminology. But I would mention in a post that my BUG+1 had an extra candidate because the absence of a mention implies a three-candidate cell.
By the way, I never was aware of that definition of BUG+N where N=number of candidates. The only important thing to me is that there is one definition and that everyone understands what it means. |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sun Dec 12, 2010 6:56 am Post subject: |
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I'm with Jeff and ronk. In BUG+n, "n" is the number of cells with more than two candidates.
In a sense, the BUG acts as pincers to reduce the number of candidates in each of these cells by two.
| Quote: | | But I would mention in a post that my BUG+1 had an extra candidate because the absence of a mention implies a three-candidate cell. |
I don't know about that. If a BUG+ cell has more than three candidates, why is that worthy of a special mention? It may be unusual, but it does not at all change the logic of the BUG.
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Dec 12, 2010 5:10 pm Post subject: |
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| keith wrote: | I'm with Jeff and ronk. In BUG+n, "n" is the number of cells with more than two candidates.
In a sense, the BUG acts as pincers to reduce the number of candidates in each of these cells by two.
| Quote: | | But I would mention in a post that my BUG+1 had an extra candidate because the absence of a mention implies a three-candidate cell. |
I don't know about that. If a BUG+ cell has more than three candidates, why is that worthy of a special mention? It may be unusual, but it does not at all change the logic of the BUG.
Keith |
Am I missing something here? For example, if a BUG+1 cell has five candidates, isn't the logic basically that of a BUG+3? I'd like to know that if someone else posted it. |
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peterj
Joined: 26 Mar 2010
Posts: 974
Location: London, UK
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| Posted: Sun Dec 12, 2010 5:42 pm Post subject: |
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| Marty R wrote: | | Am I missing something here? For example, if a BUG+1 cell has five candidates, isn't the logic basically that of a BUG+3? |
In the BUG+1 scenario regardless of whether there is one or more extra candidates you know that you can eliminate the two BUG candidates. If there is only one extra candidate that will of course solve the cell. If there is more than one it creates a pair/triple etc. which might allow further eliminations such as a locked set etc.
In a BUG+n (n>1) scenario, you know that the logic is going to include some sort of Kraken/"pincer" type logic - because you cannot make any immediate eliminations of the BUG candidates (as you don't know which cell or both to use).
So to me the cell-based (as opposed to candidate-based) numbering offers more information to the reader - just! |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Dec 12, 2010 6:15 pm Post subject: |
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| Quote: | | In a BUG+n (n>1) scenario, you know that the logic is going to include some sort of Kraken/"pincer" type logic - because you cannot make any immediate eliminations of the BUG candidates (as you don't know which cell or both to use). |
Peter, as I see it, pincer logic can also be used with multiple candidates in one cell. |
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