The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.1.|..3|...|
 |54.|...|...|
 |..6|.52|...|
 |---+---+---|
 |...|3..|7.2|
 |..3|...|9..|
 |9.2|..6|...|
 |---+---+---|
 |...|14.|8..|
 |...|...|.54|
 |...|9..|.6.|
 *-----------*


Play/Print this puzzle online

[SteveG48]

Code: Select all

 *--------------------------------------------------*
 | 2    1    8    | 4    79   3    | 6    79   5    |
 | 5    4   b79   | 6    79   1    | 23   23   8    |
 | 37   39   6    | 8    5    2    | 4    79   1    |
 *----------------+----------------+----------------|
 | 46   56   45   | 3    8    9    | 7    1    2    |
 | 1    7    3    | 5    2    4    | 9    8    6    |
 | 9    8    2    | 7    1    6    | 5    4    3    |
 *----------------+----------------+----------------|
 | 36   6-2 b57   | 1    4    57   | 8   c23   9    |
 | 378  39  b179  | 2    6    78   |c13   5    4    |
 | 48  a25   145  | 9    3    58   | 1-2  6    7    |
 *--------------------------------------------------*


(2=5)r9c2 - (5=179)r278c3 - (1=23)b9p24 => -2 r7c2,r9c7 ; stte

I'll be interested in seeing a BUG+3. I came up with one that gives 3 eliminations and still doesn't solve the puzzle. Go Cenoman!

[SpAce]

Code: Select all

.-----------------------.------------.------------.
|  2      1      8      | 4  79  3   |  6   79  5 |
|  5      4      79     | 6  79  1   |  23  23  8 |
|  37     39     6      | 8  5   2   |  4   79  1 |
:-----------------------+------------+------------:
|  46     56     45     | 3  8   9   |  7   1   2 |
|  1      7      3      | 5  2   4   |  9   8   6 |
|  9      8      2      | 7  1   6   |  5   4   3 |
:-----------------------+------------+------------:
|  36     26     7-5    | 1  4   57  |  8   23  9 |
| b78+3   39    b19+7   | 2  6   78  | b13  5   4 |
|  48    c2(5)  a14(+5) | 9  3   8-5 | c12  6   7 |
'-----------------------'------------'------------'

(5)r9c3 =[BUG+3]= (31)r8c17|(71)r8c37 - (1=25)r9c72 => -5 r7c3,r9c6; stte

[SteveG48]

And there it is!

[SpAce]

And there it is!

Sorry about the wrong delivery guy. Hope the negative delivery time compensates

[Ngisa]

Code: Select all

+-------------------+---------------+----------------+
| 2      1      8   | 4    79    3  | 6     79    5  |
| 5      4      79  | 6    79    1  | 23    23    38 |
| 37     39     6   | 8    5     2  | 4     79    1  |
+-------------------+---------------+----------------+
| 6-4    56    a45  | 3    8     9  | 7     1     2  |
| 1      7      3   | 5    2     4  | 9     8     6  |
| 9      8      2   | 7    1     6  | 35    4     3  |
+-------------------+---------------+----------------+
| 367    236   a57  | 1    4    b57 | 8     23    9  |
| 378    39     179 | 2    6     78 | 13    5     4  |
|d48     25     145 | 9    3    c58 | 12    6     7  |
+-------------------+---------------+----------------+


(4=57)r47c3 -(7=5)r7c6 - (5=8)r9c6 -(8=4)r9c1 => - 4r4c1; stte

Clement

[SteveG48]

And there it is!

Sorry about the wrong delivery guy. Hope the negative delivery time compensates

Sorry about that. We all use uniqueness, but it seems like Cenoman does so more often than the rest of us.

I was surprised when my own effort in that direction bore no fruit. When we have a reasonably simple BUG pattern (say BUG+3 or less), almost any elimination usually does the trick.

[SpAce]

Sorry about that.

No need; I was not offended

We all use uniqueness, but it seems like Cenoman does so more often than the rest of us.

How can you say that? I didn't see him use BUG here!

Just kidding. Of course you're right. I'd say it's not only more often but almost always better, at least with anything smaller than full BUGs. For example here I was happy to see what I hadn't been able to find myself despite looking at that same UR at first. Cenoman's enviable specialty is in finding the optimum combos of internals and externals for the simplest of chains. However, that's not necessary with BUGs (or at least I haven't seen it done!), which lessens the edge. Their presence is usually more obvious too, which makes them more accessible to us mere mortals.

I was surprised when my own effort in that direction bore no fruit. When we have a reasonably simple BUG pattern (say BUG+3 or less), almost any elimination usually does the trick.

You're right. This one wasn't as trivial as they usually are, so I cheated a bit by checking which guardians were true (only 5r9c3), which gave a hint to which eliminations would lead to a solution. Then it was just a matter of finding one of those eliminations with both false guardians. Normally I wouldn't do it like that.

[Cenoman]

I'll be interested in seeing a BUG+3. I came up with one that gives 3 eliminations and still doesn't solve the puzzle. Go Cenoman!

Sorry, Steve, for being busy at 1:20 pm this day ! And thank you for your message of trust !
Seeing that the BUG+3 had already been investigated, and thinking that the last word on this puzzle had been said, I finally was happy with this ALS-XZ rule:

Code: Select all

 +-------------------+-----------------+-----------------+
 |  2     1    8     |  4    79   3    |  6    79   5    |
 |  5     4    79    |  6    79   1    |  23   23   8    |
 |  37    39   6     |  8    5    2    |  4    79   1    |
 +-------------------+-----------------+-----------------+
 |  46    56  a45    |  3    8    9    |  7    1    2    |
 |  1     7    3     |  5    2    4    |  9    8    6    |
 |  9     8    2     |  7    1    6    |  5    4    3    |
 +-------------------+-----------------+-----------------+
 |  36    26   7-5   |  1    4    57   |  8    23   9    |
 |  378   39   179   |  2    6    78   |  13   5    4    |
 |  48   b25  b145   |  9    3    58   | b12   6    7    |
 +-------------------+-----------------+-----------------+

(5=4)r4c3 - (4=125)r9c237 => -5 r7c3; ste

But, then back to potential DPs, I found this BUG-lite (+2):

Code: Select all

 +-------------------+-----------------+-----------------+
 |  2     1    8     |  4    79*  3    |  6    79*  5    |
 |  5     4   c79*   |  6    79*  1    |  23   23   8    |
 |  37*   39*  6     |  8    5    2    |  4    79*  1    |
 +-------------------+-----------------+-----------------+
 |  46    56   45    |  3    8    9    |  7    1    2    |
 |  1     7    3     |  5    2    4    |  9    8    6    |
 |  9     8    2     |  7    1    6    |  5    4    3    |
 +-------------------+-----------------+-----------------+
 |  36    26  d57    |  1    4    5-7  |  8    23   9    |
 | b37+8  39* c79+1* |  2    6   a78   |  13   5    4    |
 |  48    25   145   |  9    3    58   |  12   6    7    |
 +-------------------+-----------------+-----------------+

DP(379)r8c123, r3c128, r2c35, r1c58 (*) using internals
(7=8)r8c6 - (8)r8c1==(1-97)r28c3 = (7)r7c3 => -7 r7c6; ste

[Sudtyro2]

Code: Select all

        c
+-----------------+--------------+-------------+
|  2    1    8    | 4   79  3    | 6   79  5   |
|  5    4    79   | 6   79  1    | 23  23  8   |
|  37   39   6    | 8   5   2    | 4   79  1   |
+-----------------+--------------+-------------+
| b46  b56  a45#  | 3   8   9    | 7   1   2   |b
|  1    7    3    | 5   2   4    | 9   8   6   |
|  9    8    2    | 7   1   6    | 5   4   3   |
+-----------------+--------------+-------------+
|  36   26   57   | 1   4   57   | 8   23  9   |
|  378  39   179  | 2   6   78   | 13  5   4   |
| c48   2-5  145  | 9   3  c58   | 12  6   7   |
+-----------------+--------------+-------------+

One more POV...

In 5s, a kraken 1-Fish r4\c2 + rfr4c3(#) => - 5r9c2; stte
5r4c3 - (5=64)r4c12 - (4=85)r9c16 - 5r9c2.

Or, the derived AIC from the last three nodes...
(5=64)r4c12 - (4=85)r9c16 => - 5r9c2; stte

SteveC

[SpAce]

...finding the optimum combos of internals and externals for the simplest of chains. However, that's not necessary with BUGs

That got me wondering. Can anyone think of a scenario where using externals could pay off in a BUG situation? Seems that it would in almost all cases just result in more chains for no obvious benefit. Here's a POC anyway (with four different end points ganging up on the victim for fun):

Code: Select all

.---------------------.---------------.-----------.
|  2     1     8      | 4  79    3    | 6   79  5 |
|  5     4     79     | 6  79    1    | 23  23  8 |
|  37    39    6      | 8  5     2    | 4   79  1 |
:---------------------+---------------+-----------:
| b46  c(5)6   45     | 3  8     9    | 7   1   2 |
|  1     7     3      | 5  2     4    | 9   8   6 |
|  9     8     2      | 7  1     6    | 5   4   3 |
:---------------------+---------------+-----------:
|  36    26   B7(5)   | 1  4     57   | 8   23  9 |
| b78+3  39   B19+#7  | 2  6  aC#7#8  | 13  5   4 |
| b48    2-5  A14(+5) | 9  3    C8(5) | 12  6   7 |
'---------------------'---------------'-----------'


BUG+3 using mixed +internals and #externals. (Externals for r8c1.)

(+5)r9c3
||
(+#75)r87c3
||
(#85)r89c6
||
(#7-8)r8c6 = (846)r894c1 - (6=5)r4c2

=> -5 r9c2; stte

(or at least I haven't seen it done!)

Now I have... but not so sure I wanted to With just internals I'd write the same elimination as:

(5)r9c3 == (3|7,8)r8c13,6 - (8=5)r9c6 => -5 r9c2; stte