| View previous topic :: View next topic |
| Author |
Message |
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
 Posted: Wed Aug 22, 2007 1:10 pm Post subject: 22 Aug VH |
 |
|
| I used an xyz wing which is easy enough to spot cos after basic eliminations there's only one square left with 3 numbers. |
|
| Back to top |
|
 |
TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
|
| Posted: Wed Aug 22, 2007 1:32 pm Post subject: |
|
|
Which means it was also a BUG+1, for those who don't find that technique objectionable.
Also saw a couple of XY-wings & W-wings that would do the trick. |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Wed Aug 22, 2007 3:25 pm Post subject: |
|
|
| I used a W-Wing which didn't appear to do much and I don't recall if it exposed the XY-Wing which finished the puzzle. |
|
| Back to top |
|
|
nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
|
| Posted: Wed Aug 22, 2007 6:28 pm Post subject: |
|
|
| Quote: | | I used an xyz wing which is easy enough to spot cos after basic eliminations there's only one square left with 3 numbers. |
indeed. A "one trick pony" ... |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Wed Aug 22, 2007 8:41 pm Post subject: |
|
|
| Quote: | | Which means it was also a BUG+1, for those who don't find that technique objectionable. |
I looked up BUGs and they're cool. Let me get it right eh!
A BUG means the grid can't be solved or that there are 2 solutions. A BUG situation means there are ONLY PAIRS left - and that there are two of each number in every row, column and box. So if you have ONE cell with THREE numbers it's a BUG+1. You can remove the number from that cell that will give a BUG situation (i.e. 2 Nos every row, col, box) - then put it back as the right answer - cos Sudoku.com promised that all puzzles can be solved with one solution.
I would have thought situations like that are rare - but then again one just occured. My only objection is the esoteric acronym. Bivalue Universal Grave indeed - I can think of a more appropriate Bug***** word. |
|
| Back to top |
|
|
Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
|
| Posted: Wed Aug 22, 2007 9:30 pm Post subject: |
|
|
| cgordon wrote: | | You can remove the number from that cell that will give a BUG situation |
Actually, two of the digits in that cell produce the BUG situation. You can immediately place the one digit that prevents the BUG. It is easy to spot: it is the only one of the three digits that occurs three times in the House. (Box, Column or Row, it doesn't matter which. Only one of the digits occurs three times in all three of these and that is the one you keep.) |
|
| Back to top |
|
|
George Woods
Joined: 28 Mar 2006
Posts: 304
Location: Dorset UK
|
| Posted: Thu Aug 23, 2007 7:56 am Post subject: Forgotten the name of this |
|
|
| Code: |
+-------------+---------+------------+
| 2 7 4 | 1 8 5 | 6 3 9 |
| 3 18 18 | 2 9 6 | 4 7 5 |
| 9 5 6 | 34 7 34 | 8 2 1 |
+-------------+---------+------------+
| 5 3 2 | 6 4 1 | 7 9 8 |
| 67 69 79 | 5 2 8 | 13 14 34 |
| 18 4 18 | 9 3 7 | 2 5 6 |
+-------------+---------+------------+
| 4 2 79 | 8 1 39 | 5 6 37 |
| 68 68 3 | 7 5 49 | 19 14 2 |
| 17 19 5 | 34 6 2 | 39 8 347 |
+-------------+---------+------------+
|
I reached the following position (hopefully not by a lucky error) and I half remember a move that says if every unsolved cell bar 1 is a double, then the triple can be solved as the number common to the strongly connected set.
Don't know if I have quoted the rules correctly, and I guess it only applies if there is no direct further move.
In any event I applied the rule and put a 3 in r9c9 since all the c9 set contains 3, and of course it then falls out! |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Thu Aug 23, 2007 3:50 pm Post subject: |
|
|
| George, it's called the BUG+1 pattern. The trivalue cell needs to be solved with the number that appears three times. If that candidate were eliminated then the deadly BUG pattern would result. |
|
| Back to top |
|
|
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
