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Help requested with MUGs and Over Lapping URs

 
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tlanglet



Joined: 17 Oct 2007
Posts: 2461
Location: Northern California Foothills

PostPosted: Sun Aug 24, 2008 11:14 pm    Post subject: Help requested with MUGs and Over Lapping URs Reply with quote

I am in a rut where every puzzle seems to offer a possible MUG, overlapping URs , and/or overlapping MUG & UR. To make matter worst, I am becoming more confused about treating these situations.

The following code is the LA Times online for August 24.
Code:

 *-----------*
 |...|.8.|.3.|
 |4..|...|..1|
 |95.|.4.|...|
 |---+---+---|
 |...|.26|.94|
 |3..|...|..7|
 |29.|37.|...|
 |---+---+---|
 |...|.6.|.85|
 |54.|...|..6|
 |.8.|71.|...|
 *-----------*



Basics get me to here.

Code:


 *--------------------------------------------------------------------*
 | 17     126    1267   | 5      8      12     | 4      3      9      |
 | 4      23     8      | 29     39     7      | 56     56     1      |
 | 9      5      13     | 6      4      13     | 8      7      2      |
 |----------------------+----------------------+----------------------|
 | 8      7      5      | 1      2      6      | 3      9      4      |
 | 3      16     4      | 89     5      89     | 126    126    7      |
 | 2      9      16     | 3      7      4      | 156    156    8      |
 |----------------------+----------------------+----------------------|
 | 17     123    12379  | 4      6      239    | 1279   8      5      |
 | 5      4      12379  | 289    39     2389   | 1279   12     6      |
 | 6      8      29     | 7      1      5      | 29     4      3      |
 *--------------------------------------------------------------------*


At this point I see a possible MUG in r789c367. Is this a valid <abc> 3x3 MUG? If so what are the digits: <129> or <279>? Is this really two MUGs in the same grid? Or, is this an incomplete (invalid) 4 x 4 MUG including r1c1 on <1279>?

If we have a valid MUG as shown above, then a UR on <89> at r58c46 overlays it sharing the digit <9>. How does this impact the situation.

If the above is not a valid MUG, I believe that we can independently analyze three URs as follows:
UR on <29> at r79c37
UR on <29> at r89c37
UR on <89> at r58c46

Many other UR combinations also exist; <17>, <23>,<19>, etc.

(And yes a Type 2 UR on <56> at r26c78 also exists)

I have read, and re-read the two posts by Myth, but I still fail to grasp the logic to deal with MUGs and the recent "over lapping" URs. Any comments and references to other posts will be greatly appreciated.

Ted Confused Confused Confused
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Steve R



Joined: 24 Oct 2005
Posts: 289
Location: Birmingham, England

PostPosted: Mon Aug 25, 2008 1:01 pm    Post subject: Reply with quote

Ted

I donít see how r789c367 can form a MUG because one of the cells, r9c6 already has an entry.

Generally speaking all the cells in the pattern should be unfilled and, whichever basis candidates you choose, each cell in the pattern should be open to one of them.

Most likely I have misunderstood your point. However that may be, there is a MUG in your grid. Why not check columns 7 and 8, specifically r3568c78? I think you will readily find four basis candidates which allow you to eliminate 1 and 2 from r8c7.

The easiest MUG patterns to spot are those confined to two rows in a band or two columns in a stack. Take two rows in a band as an example. You donít need to worry too much about how many columns the pattern occupies: if n columns are involved, you need to find n basis candidates to work with.

Iím far too old to get involved with complicated rules covering overlapping MUGs and URs so I canít help with that but by all means come back on MUGs if it would be helpful.

Steve
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