| View previous topic :: View next topic |
| Author |
Message |
Johan
Joined: 25 Jun 2007
Posts: 206
Location: Bornem Belgium
|
 Posted: Tue Aug 21, 2007 9:02 pm Post subject: Type 2 UR |
 |
|
cg,
Found this diagram on a website for Type 2 UR
For avoiding the deadly pattern R1C2 or R1C3 must contain a <6>, so both <6>'s in R2C2 and R1C8 should be eliminated.
| Code: |
+------------+-------+---------+
| 7 *356*356 | 1 9 2 |4 5-6 8 |
| 12 2-6 4 | 8 5 3 | 7 69 19 |
| 15 8 9 | 6 4 7 | 3 2 15 |
+------------+-------+---------+
| 9 1 2 | 5 7 4 | 8 3 6 |
| 6 *35 *35 | 2 1 8 | 9 7 4 |
| 4 7 8 | 3 6 9 | 5 1 2 |
+------------+-------+---------+
| 3 4 1 | 9 2 5 | 6 8 7 |
| 25 259 7 | 4 8 6 | 1 59 3 |
| 8 569 56 | 7 3 1 | 2 4 59 |
+------------+-------+---------+
|
|
|
| Back to top |
|
 |
TKiel
Joined: 22 Feb 2006
Posts: 292
Location: Kalamazoo, MI
|
| Posted: Tue Aug 21, 2007 9:09 pm Post subject: |
|
|
I'm trying to find the spot where Marty R. found and used the 'Type 2 UR'. I looked at the UR link above and saw nothing listed for a 'Type 2'. I have a vague notion that a 'Type 2' involves a naked pair on the 'roof' of the UR (which sounds a little kinky) and the exclusion are in cells not part of the UR, but don't know from where that thought comes.
This is the grid after the 83-34-48 XY-wing has been used and all the resultant singles placed. The exclusions from the naked pair in R4 have been made, but not from the one in R7. There is a potential UR involving <26> in r46c19.
| Code: |
*-----------------------------------------------------------*
| 7 124 9 | 46 5 8 | 3 16 246 |
| 2346 5 1246 | 46 39 7 | 1269 8 2469 |
| 8 34 46 | 1 39 2 | 69 5 7 |
|-------------------+-------------------+-------------------|
| 26 9 58 | 3 4 1 | 58 7 26 |
| 34 7 48 | 2 6 5 | 189 19 39 |
| 236 123 1256 | 7 8 9 | 256 4 236 |
|-------------------+-------------------+-------------------|
| 1 24 24 | 8 7 3 | 69 69 5 |
| 9 6 3 | 5 1 4 | 7 2 8 |
| 5 8 7 | 9 2 6 | 4 3 1 |
*-----------------------------------------------------------*
|
Is this a 'Type 2"?
What are the exclusions (if any) and the logic for each?
Edit: I was writing this when Johan made his post. According to that explanation, one of r6c19 must be <3> to avoid the deadly pattern, so r6c2 can have the <3> excluded, which means r3c2 must be <3>.
Last edited by TKiel on Wed Aug 22, 2007 1:00 am; edited 1 time in total |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Tue Aug 21, 2007 9:41 pm Post subject: |
|
|
Tracy: The link could have been made clearer. It jumps from Type 1 to Type 5 and simply states that Type 2 URs are "obvious variations". The way I see it is that if you have a rectangle with two 26's and two 236's (as in this grid) - you can knock off any 3's that are shared by the two 236's. For Type 5s the 236s are diagonal - For Type 2s they are in the same column or row. (Why bother calling them Type 5s I say).
So by my reckoning in this case you can eliminate all the other 3's on Row 6. Hope I got that right. |
|
| Back to top |
|
|
Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
|
| Posted: Wed Aug 22, 2007 12:30 am Post subject: |
|
|
| Quote: | | For Type 5s the 236s are diagonal - For Type 2s they are in the same column or row. (Why bother calling them Type 5s I say). |
On the Type 5s, eliminations can be made in two different houses, as there is a pincerlike effect.
P.S. I misspoke in an earlier post when I wrote, "However, I had only a 26 in r4c9 and one of them was a strong link in row 6, so it was a Type 2 with the roof cells both being 236."
Of course, the strong link comes into play on a Type 4, not a Type 2. |
|
| Back to top |
|
|
keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
|
| Posted: Wed Aug 22, 2007 4:18 am Post subject: |
|
|
| cgordon wrote: | | Tracy: The link could have been made clearer. It jumps from Type 1 to Type 5 and simply states that Type 2 URs are "obvious variations". The way I see it is that if you have a rectangle with two 26's and two 236's (as in this grid) - you can knock off any 3's that are shared by the two 236's. |
Which is correct. What, then, could be "clearer"?
| cgordon wrote: | | (Why bother calling them Type 5s I say). |
Perhaps because the original description of a Type 2 does not recognize a diagonal variant? Perhaps because a useful Type 5 has never been found?
Perhaps because the pedagogy is to make you think about them, and understand them for yourself?
Perhaps because the author of the UR guide did not establish the UR classification terminology, and did not want to make a new one?
Keith |
|
| Back to top |
|
|
cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
|
| Posted: Wed Aug 22, 2007 11:38 am Post subject: |
|
|
| Quote: | | Perhaps because the pedagogy is to make you think about them, and understand them for yourself? |
As they say: "A picture is worth a 1000 words". Sudkos are often hard enough to follow when explanatory diagrams are provided. |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
