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Free Press May 11, 2012
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ronk



Joined: 07 May 2006
Posts: 398

PostPosted: Fri May 18, 2012 1:53 pm    Post subject: Reply with quote

Luke451 wrote:
Now I'm wondering if just these four cells are enough to make the Reverse Bug-Lite elimination of r4c3<>2.

What if you didn't know that (17)r46c19 was already resolved?
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aran



Joined: 19 Apr 2010
Posts: 70

PostPosted: Sun May 20, 2012 1:20 pm    Post subject: Reply with quote

Luke451 wrote:
I looked into the Reverse BUG-Lite perspective. This may be the way to go when the MUG gets big Idea
Code:
 *-----------------------------------------------------------*
 | 9     8     7     | 5     1     2     | 4     3     6     |
 | 4     6     1     | 7     3     9     | 2     8     5     |
 | 2     5     3     | 6     48    48    | 7     1     9     |
 |-------------------+-------------------+-------------------|
 | 1     49   *25    | 3489 *6     345   | 38    4592  7     |
 | 8     3     25    | 149   479   1457  | 59    6     24    |
 | 7     49   *6     | 3489 *2     345   | 38    459   1     |
 |-------------------+-------------------+-------------------|
 | 6     127   9     | 134   47    1347  | 15    2457  8     |
 | 3     127   8     | 149   5     6     | 19    2479  24    |
 | 5     17    4     | 2     789   178   | 6     79    3     |
 *-----------------------------------------------------------*

Now I'm wondering if just these four cells are enough to make the Reverse Bug-Lite elimination of r4c3<>2. This grid is a little different than most Rev B-L in that at this point the (6) value is solved for the whole puzzle.

It could be thought of like this : the 9-N pattern being the Reverse to the N-pattern (my own jargon) is not a deadly pattern in its own right, but only by repercussion insofar as it bring about an "in its own right" deadly N-pattern.
The 9-N pattern may contain givens : the N-pattern must not contain givens.
In the above therefore the reduced version to which you point is
a) not deadly in its own right because it contains givens
b) not deadly by repercussion because it does not bring about a GIVEN-FREE N-pattern. ie the N-pattern which it would generate 1345789r46c1246789 contains givens 17 in r46c19.
Being given, as ronk points out, they are not xx (so we cannot use the logic "if any solution S exists, then W is also a solution where W is the "xx").
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