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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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 Posted: Wed Feb 04, 2015 8:39 pm Post subject: another Brainbasher VH Feb 3 and an unkown type of solution |
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| Code: |
+------------+------------+-------------+
| 8 5 3 | 6 4 1 | 2 9 7 |
| 67 1267 9 | 58 257 78 | 3 4 15 |
| 4 127 17 | 9 257 3 | 56 156 8 |
+------------+------------+-------------+
| 3 67 2 | 58 9 678 | 1 567 4 |
| 67 18 18 | 2 57 4 | 567 3 9 |
| 9 4 5 | 1 3 67 | 8 67 2 |
+------------+------------+-------------+
| 5 78 4 | 3 1 2 | 9 78 6 |
| 2 3 78 | 4 6 9 | 57 1578 15 |
| 1 9 6 | 7 8 5 | 4 2 3 |
+------------+------------+-------------+
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Play this puzzle online at the Daily Sudoku site
This is the grid after fundamentals
Once again I Don't know what my solution is called/
if r5c5 is 7 then via col 1 7s r2c1 is 7 and box 2 is denied a 7 so r5c5 must be 5. Maybe this just another forcing chain.
Braibashers do seem to demand a little more thought than just applying a rule such as x,xy and xyz wings |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Feb 05, 2015 12:28 am Post subject: |
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| Look at the 7's in rows 2 and 5 with those in block 2. This is called an empty rectangle. You can remove the 7 in r5c5. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Thu Feb 05, 2015 7:40 am Post subject: thanks Archietech |
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I had wondered about calling it a compound xy 767* wing with pivot at r5c1 and 7's bearing down on r2c6 i.e if pivot is 6 then the 7 at r3c1 is one wing and if pivot is 7 then the other wing is the pair of 7 at r46c6.
Your empty rectangle is almost identical but comes from setting r2c1 as pivot and so to two wings of 7 7 bearing down on r5c5. What is not clear to me is the "empty rectangle" descripto and does this description aid in spotting it . For me it it is a type of 3 cell wing |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Feb 05, 2015 2:26 pm Post subject: |
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| Code: | +------------+------------+-------------+
| 8 5 3 | 6 4 1 | 2 9 7 |
| 67 1267 9 | 58 257 78 | 3 4 15 |
| 4 127 17 | 9 257 3 | 56 156 8 |
+------------+------------+-------------+
| 3 67 2 | 58 9 678 | 1 567 4 |
| 67 18 18 | 2 57 4 | 567 3 9 |
| 9 4 5 | 1 3 67 | 8 67 2 |
+------------+------------+-------------+
| 5 78 4 | 3 1 2 | 9 78 6 |
| 2 3 78 | 4 6 9 | 57 1578 15 |
| 1 9 6 | 7 8 5 | 4 2 3 |
+------------+------------+-------------+
I spot them where in a block a digit forms 2 sides of a rectangle resulting in the digit being true in a column and/or row.
In this puzzle in block 2 if the 7 is in column 5 there cannot be a 7 in r5c5
if the 7 is in row 2 then -7r2c1=7r5c1 there cannot be a 7 in r5c5
How this came to be called "empty rectangle" I do not know. |
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George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
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| Posted: Thu Feb 05, 2015 6:07 pm Post subject: Brainbasher VH feb 5 similarity to feb 4? |
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| Code: |
+-----------+-----------+------------+
| 7 13 39 | 2 14 5 | 8 6 49 |
| 19 8 2 | 6 3 14 | 7 5 49 |
| 5 6 4 | 9 7 8 | 1 2 3 |
+-----------+-----------+------------+
| 6 13 8 | 7 2 139 | 4 139 5 |
| 19 7 359 | 4 15 6 | 23 8 129 |
| 2 4 359 | 35 8 139 | 6 139 7 |
+-----------+-----------+------------+
| 8 2 1 | 35 45 34 | 9 7 6 |
| 3 9 7 | 1 6 2 | 5 4 8 |
| 4 5 6 | 8 9 7 | 23 13 12 |
+-----------+-----------+------------+
|
Play this puzzle online at the Daily Sudoku site
Is this another one? The strong link of 1 in r2 and c1 and the pattern of 1s in box 5 are familiar and quite simply r5c1 cannot be 1 since this kills all the 1s in box5 - so if this is an empty rectangle Ican half see it |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Thu Feb 05, 2015 7:54 pm Post subject: Re: Brainbasher VH feb 5 similarity to feb 4? |
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| George Woods wrote: | | Code: |
+-----------+-----------+------------+
| 7 13 39 | 2 14 5 | 8 6 49 |
| 19 8 2 | 6 3 14 | 7 5 49 |
| 5 6 4 | 9 7 8 | 1 2 3 |
+-----------+-----------+------------+
| 6 13 8 | 7 2 139 | 4 139 5 |
| 19 7 359 | 4 15 6 | 23 8 129 |
| 2 4 359 | 35 8 139 | 6 139 7 |
+-----------+-----------+------------+
| 8 2 1 | 35 45 34 | 9 7 6 |
| 3 9 7 | 1 6 2 | 5 4 8 |
| 4 5 6 | 8 9 7 | 23 13 12 |
+-----------+-----------+------------+
|
Play this puzzle online at the Daily Sudoku site
Is this another one? The strong link of 1 in r2 and c1 and the pattern of 1s in box 5 are familiar and quite simply r5c1 cannot be 1 since this kills all the 1s in box5 - so if this is an empty rectangle Ican half see it |
Look at the 1's in b5 if a 1 is in c6 then -1r2c6
else r5c5 must be 1 and -1r5c1=1r2c1 then -1r2c6 |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Thu Feb 05, 2015 7:58 pm Post subject: Re: Brainbasher VH feb 5 similarity to feb 4? |
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| George Woods wrote: | | Code: |
+-----------+-----------+------------+
| 7 13 39 | 2 14 5 | 8 6 49 |
| 19 8 2 | 6 3 14 | 7 5 49 |
| 5 6 4 | 9 7 8 | 1 2 3 |
+-----------+-----------+------------+
| 6 13 8 | 7 2 139 | 4 139 5 |
| 19 7 359 | 4 15 6 | 23 8 129 |
| 2 4 359 | 35 8 139 | 6 139 7 |
+-----------+-----------+------------+
| 8 2 1 | 35 45 34 | 9 7 6 |
| 3 9 7 | 1 6 2 | 5 4 8 |
| 4 5 6 | 8 9 7 | 23 13 12 |
+-----------+-----------+------------+
|
Play this puzzle online at the Daily Sudoku site
Is this another one? The strong link of 1 in r2 and c1 and the pattern of 1s in box 5 are familiar and quite simply r5c1 cannot be 1 since this kills all the 1s in box5 - so if this is an empty rectangle Ican half see it |
George,
I'm sure someone will correct me if I'm wrong. In box 2, 1 occurs in r1 and c6. These two lines intersect at r1c6 and this is called Empty Rectangle Intersection (ERI).When there is a strong link in a line such as 1s in r14c2,
if one of the cells of that strong link sees the ERI, then that cell may not contain the number in question (1 in this case.)
While you're correct about r5c1, the ER only denies a 1 in r1c2 and r6c6. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Fri Feb 06, 2015 3:05 am Post subject: |
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| Quote: | | How this came to be called "empty rectangle" I do not know. |
I think it goes back to the early definition. Find four cells in a box that form a rectangle and none of the cells contain a particular number, thus the rectangle is "empty" of that number. |
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