View previous topic :: View next topic 
Author 
Message 
Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Sat Feb 02, 2008 12:38 am Post subject: 


I only went two days this time. Can an inference be made based on an assumption of true in two or more cells? Consider these two cells in a line:
23g 2g34
Can we say that if 2g3g are both true, then the 4 can be inferred, thus creating a wrap? Seems too easy.
Or this:
38g 35g 158
Can we infer the 1 assuming that the 5g8g are both true? 

Back to top 


Asellus
Joined: 05 Jun 2007 Posts: 865 Location: Sonoma County, CA, USA

Posted: Sat Feb 02, 2008 7:02 am Post subject: 


Marty R. wrote:  Can an inference be made based on an assumption of true in two or more cells? 
Yes, but...
In your first example, I don't see that there is any inference about the <4> in those two cells. We only know that the <4> is false if G is true (since in that case the cell must be <2>). But, that isn't very helpful. I certainly can't see a "wrap."
However, if that <4> were strongly linked to another <4> that already shared a cell with a "g" value, then you would have a wrap (since G would eliminate all <4>s in that house).
In the second example, we can infer that the <1> is "g", but not that it is true. In other words, if G is true, then the third cell must be <1>, hence, it can be colored "g".
I hope that is clear. 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Sat Feb 02, 2008 4:16 pm Post subject: 


A,
Thanks, I hope for the last time.
I wasn't thinking very clearly when I presented my first example. How can you infer a cell is "x" if you assume it's "y'"? 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Thu Feb 21, 2008 4:29 pm Post subject: 


Consider the following partial grid with madeup numbers just to illustrate the point:
Code:  ++++
 . . .  . . .  49g . . 
 . . .  . . .  139 . . 
 . . .  . . .  13 . . 
++++
 . . .  . . .  17 . . 
 . . .  . . .  . 69g . 
 . . .  . . .  . . . 
++++
 . . .  . . .  . . . 
 . . .  . . .  . . . 
 . . .  . . .  . . . 
++++

The 9g in box 6 has inferred the 9g in box 3. The latter 9g infers a naked 13 pair just below it. Is this a legitimate trap whereby r4c7 can be solved for 7? I'm used to my traps coming from little r's and g's.
Or is all we can do is mark the 7 with a "g"?
(First question in 20 days). 

Back to top 


Asellus
Joined: 05 Jun 2007 Posts: 865 Location: Sonoma County, CA, USA

Posted: Fri Feb 22, 2008 12:02 am Post subject: 


Marty wrote:  Is this a legitimate trap whereby r4c7 can be solved for 7? ... Or is all we can do is mark the 7 with a "g"? 
All you can do is mark the 7 with a "g". The <1> can only be removed if it can "see" a red <1> somewhere.
[Edit to remove unnecessary comment.] 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Fri Feb 22, 2008 1:19 am Post subject: 


As always, thanks. 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Mon Mar 31, 2008 12:35 am Post subject: 


Code:  ++++
 . . .  . . .  . . . 
 . . .  . . .  . 4a8 . 
 . . .  . . .  . . . 
++++
 . . .  . . .  . . . 
 . . .  . . .  . 36b . 
 . . .  . . .  . . . 
++++
 . . .  . . .  . . . 
 . . .  . . .  . . . 
 . . .  . . .  . 469 . 
++++ 
The actual values shown are just for illustration. If I infer from the 4a, then r9c8 = 69. If I infer from the 6b, then r9c8 = 49. The 9 is there based on inferences from both a and b, so I placed it. Valid or did I just get lucky this one time? 

Back to top 


Asellus
Joined: 05 Jun 2007 Posts: 865 Location: Sonoma County, CA, USA

Posted: Tue Apr 01, 2008 8:37 pm Post subject: 


Marty wrote:  Valid or did I just get lucky this one time? 
I believe that was luck. I don't see it as a valid placement. All you know is that r9c8 is either {69} or it is {49}. <4> and <6> are still possibilities. 

Back to top 


Marty R.
Joined: 12 Feb 2006 Posts: 5061 Location: Rochester, NY, USA

Posted: Tue Apr 01, 2008 9:22 pm Post subject: 


As always, thanks. I guess I'll avoid that type of thing in the future. But I do understand what you're saying. 

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
