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What do you call this?

Here are a couple of examples where the candidate X must be the right one because otherwise the cells would form a deadly pattern (in both cases, the choice of cell to which the X is attached is arbitrary). Do either have a special name or are subsumed in some other solving technique, or are they just "deadly patterns" / "uniqueness tests"? If the answer is already on the 'pedia then point me to it and I'll happily RTFM. Cheers.

 . 12  .  |  . 12X .  |  .  .  .
 . 23  .  |  . 23  .  |  .  .  .
 . 13  .  |  . 13  .  |  .  .  .

12  .  .  | 12  .  .  |  .  .  .
 . 23  .  | 23  .  .  |  .  .  . 
 .  . 13  | 13X .  .  |  .  .  .
----------+-----------+----------
12 23 13  |  .  .  .  |  .  .  .
 .  .  .  |  .  .  .  |  .  .  .
 .  .  .  |  .  .  .  |  .  .  .

81.151.186.149 19:58, 27 December 2006 (CET)

I am not a terminology expert, but as far as I know, you can call all of these "deadly patterns". More specifically, I think, since these are between Unique Rectangles and BUGs, you can call these BUG Lites.

--unkx80 12:33, 28 December 2006 (CET)

OK, got it. Have rewritten the main article accordingly (and then some). Comments? 81.151.186.149 20:08, 29 December 2006 (CET)

7 cells deadly pattern

I have found 7 cells deadly patterns as well:

One schute form:

+---------+---------+---------+
| .  12 . | .  12 . | .  .  . |
| .  13 . | .  12 . | .  23 . |
| .  23 . | .  .  . | .  23 . |
+---------+---------+---------+

"Corner" form:

+---------+---------+---------+
| 12 13 . | .  23 . | .  .  . |
| 23 .  . | .  23 . | .  .  . |
| .  .  . | .  .  . | .  .  . |
+---------+---------+---------+
| .  .  . | .  .  . | .  .  . |
| 13 13 . | .  .  . | .  .  . |
| .  .  . | .  .  . | .  .  . |
+---------+---------+---------+

But I do not have any real life example.

Damaged Deadly Patterns

The examples above show up an interesting weakness in the article as it stands.

Let's look at the first example in particular. It satisfies all three points in the definition given in the article, so seems to be a valid deadly pattern. But look at its solutions:

+---------+---------+---------+       +---------+---------+---------+
| .  1  . | .   2 . | .  .  . |       | .   2 . | .  1  . | .  .  . |
| .   3 . | .  1  . | .  2  . |  and  | .  1  . | .   2 . | .   3 . |
| .  2  . | .  .  . | .   3 . |       | .   3 . | .  .  . | .  2  . |
+---------+---------+---------+       +---------+---------+---------+

If we really were dealing with a deadly pattern then both of these would be valid solutions (that's the "deadly" bit). But in that case, we could permute the URs in each to obtain the following extra pair of valid solutions ...

+---------+---------+---------+       +---------+---------+---------+
| .  1  . | .   2 . | .  .  . |       | .   1 . | .  2  . | .  .  . |
| .   2 . | .  1  . | .  3  . |  and  | .  2  . | .   1 . | .   3 . |
| .  3  . | .  .  . | .   2 . |       | .   3 . | .  .  . | .  2  . |
+---------+---------+---------+       +---------+---------+---------+

... in which case, the original deadly pattern should have looked like this:

+---------+---------+---------+
| .  12 . | .  12 . | .  .  . |
| . 123 . | .  12 . | .  23 . |
| .  23 . | .  .  . | .  23 . |
+---------+---------+---------+

Note the extra digit, shown in bold. With this extra digit, the pattern is no longer deadly by the definition given in the article.

Can this situation occur in real life, where a deadly pattern is apparently missing some digits? I don't know. I suspect something like this can occur due to inference chains. Will have to give it some more thought and then probably revise the article.

Do 7 cells patterns belong to MUG?

It looks like both 7 cells patterns with additional candidate belong to MUG family.

MUG?

What's a MUG? Could you post a reference please?

Myth Jellies wrote about MUG = Multivalued Universal Graves in forum long time ago (Feb 2006) Forum