The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.9.|2..|..3|
 |.43|1..|2..|
 |1..|.64|5..|
 |---+---+---|
 |..8|..7|.2.|
 |...|...|...|
 |.5.|6..|9..|
 |---+---+---|
 |..1|45.|..9|
 |..4|..6|75.|
 |5..|..2|.3.|
 *-----------*


Play/Print this puzzle online

[Ngisa]

Code: Select all

+---------------------+-----------------+--------------------+
| 6        9       5  | 2     7       8 | 14     14      3   |
|i7-8      4       3  | 1     9       5 | 2      78      6   |
| 1        278    a27 | 3     6       4 | 5      9       78  |
+---------------------+-----------------+--------------------+
| 9       f13      8  | 5     34      7 | 6      2       14  |
| 247     e127     6  | 8     24      9 | 3     d147     5   |
| 2347     5      b27 | 6     234     1 | 9     c478    c478 |
+---------------------+-----------------+--------------------+
| 27       27      1  | 4     5       3 | 8      6       9   |
|h38      g38      4  | 9     1       6 | 7      5       2   |
| 5        6       9  | 7     8       2 | 14     3       14  |
+---------------------+-----------------+--------------------+


(7)r3c3 = r6c3 - r6c89 = (7-1)r5c8 = r5c2 - (1=3)r4c2 - (3=8)r8c2 - r8c1 = (8)r2c1 => - 7r2c1; stte

Clement

[SteveG48]

Code: Select all

 *-----------------------------------------------------------*
 | 6     9     5     | 2     7     8     | 14    14    3     |
 |c78    4     3     | 1     9     5     | 2     78    6     |
 | 1    d278   27    | 3     6     4     | 5     9     78    |
 *-------------------+-------------------+-------------------|
 | 9     13    8     | 5     34    7     | 6     2     14    |
 |b247 bd127   6     | 8     24    9     | 3    a147   5     |
 | 2347  5     27    | 6     234   1     | 9     478   78    |
 *-------------------+-------------------+-------------------|
 |b27  bd27    1     | 4     5     3     | 8     6     9     |
 | 38    38    4     | 9     1     6     | 7     5     2     |
 | 5     6     9     | 7     8     2     | 14    3     14    |
 *-----------------------------------------------------------*


7r5c8 = (7X-wing r57c12) - (7=8)r2c1 - (8=127)r357c2 => -1 r5c8 ; stte

[SpAce]

Ugly.

Code: Select all

.-------------------.-----------.-------------------.
|   6      9     5  | 2  7    8 | 14   14      3    |
| bc78     4     3  | 1  9    5 | 2   a78      6    |
|   1     c278  d27 | 3  6    4 | 5    9       78   |
:-------------------+-----------+-------------------:
|   9    fg13    8  | 5  34   7 | 6    2      g1(4) |
|  f247   f127   6  | 8  24   9 | 3   g14(7)   5    |
|   2347   5    e27 | 6  234  1 | 9  a(8)-47   78   |
:-------------------+-----------+-------------------:
|   27     27    1  | 4  5    3 | 8    6       9    |
|   38   de38    4  | 9  1    6 | 7    5       2    |
|   5      6     9  | 7  8    2 | 14   3       14   |
'-------------------'-----------'-------------------'

(8)r[6=2]c8 - r2c1 = (87)b1p84 - (8|7)r8c2,r3c3 = (37)r8c2,r6c3 - (3|7)r4c2,r5c12 = (147)r4c29,r5c8 => -47 r6c8; stte

[SpAce]

7r5c8 = (7X-wing r57c12) - (7=8)r2c1 - (8=127)r357c2 => -1 r5c8 ; stte

Very nice! It's a rare treat for me to spot such useful almost-fishes

Btw, my personal preference of writing it with the UFG-style:

7r5c8 = r57\c12 - (7=8)r2c1 ...

or:

7r5c8 = 7:r57\c12 - (7=8)r2c1 ...

[Sudtyro2]

Code: Select all

+--------------------+-------------+-----------------+
|  6      9     5    | 2   7    8  | 14   14      3  |
| e8-7*   4     3    | 1   9    5  | 2   C78*     6  |
|  1      278#  27*  | 3   6    4  | 5    9     B78  |
+--------------------+-------------+-----------------+
|  9     c13    8    | 5   34   7  | 6    2      14  |
|  247   b127   6    | 8   24   9  | 3   a147#   5   |
|  2347#  5     27*  | 6   234  1  | 9    478*  A78# |
+--------------------+-------------+-----------------+
|  27     27    1    | 4   5    3  | 8    6      9   |
| d38    c38    4    | 9   1    6  | 7    5      2   |
|  5      6     9    | 7   8    2  | 14   3      14  |
+---------------+------------------+-----------------+

In 7s, a 5-link oddagon(*) with four guardians(#).

Code: Select all

(7-1)r5c8 = r5c2 - (1=38)r48c2 - r8c1 = 8r2c1 - 7r2c1; abcde
7r6c9 - r3c9 = 7r2c8                          - 7r2c1; ABC
7r3c2,r6c1                                    - 7r2c1; stte

SteveC

[Cenoman]

Code: Select all

 +--------------------+------------------+------------------+
 |  6      9     5    |  2    7     8    |  14   14    3    |
 |  78     4     3    |  1    9     5    |  2    78    6    |
 |  1      278*  27*  |  3    6     4    |  5    9     78   |
 +--------------------+------------------+------------------+
 |  9     c13    8    |  5    34    7    |  6    2    d14   |
 |  247    127   6    |  8    24    9    |  3    147   5    |
 | b2347*  5     2-7* |  6    234   1    |  9  da478 da78   |
 +--------------------+------------------+------------------+
 |  27*    27*   1    |  4    5     3    |  8    6     9    |
 |  38     38    4    |  9    1     6    |  7    5     2    |
 |  5      6     9    |  7    8     2    |  14   3     14   |
 +--------------------+------------------+------------------+

DP(27)r367c123 using internals (BUG-lite)
The DP has three internals, but the chains 8r3c2-r8c2=(8-3)r8c1=3r6c1 and 3r6c1-r8c1=(3-8)r8c2=8r3c2 demonstrate that 8r3c2 and 3r6c1 are equivalent (true or false together). So, 3r6c1 & 4r6c1 are considered.
(78=4)r6c89 - (4==3)r6c1 - (3=1)r4c2 - (1=487)b6p389 => -7 r6c3; ste

[SteveG48]

Btw, my personal preference of writing it with the UFG-style:

7r5c8 = r57\c12 - (7=8)r2c1 ...

So the backslash represents an X-wing, or is it something more general? Certainly looks clean. Tell me again where I can find a tutorial on this notation.

[SpAce]

7r5c8 = r57\c12 - (7=8)r2c1 ...

So the backslash represents an X-wing, or is it something more general? Certainly looks clean. Tell me again where I can find a tutorial on this notation.

It's from the Ultimate Fish Guide. The backslash separates the base and cover sectors (houses), or truths and links in Allan Barker's set logic terms. In this case r57 are the base sectors, and because there are two of them, it's a 2-fish i.e. X-Wing. Since there are two cover sectors (c12) as well, it's a finless fish (i.e. Rank 0 in set logic terms). At first I didn't like the backslash because it reminds me of Windows paths, but I guess it means set difference in mathematics so it actually makes sense.

There's also a standard UFG notation for finned fishes but personally I prefer the Obi-Wahn notation of just adding more cover sectors for the fins (i.e. using Rank 1+ logic). Neither the UFG or the Obi-Wahn system includes other than single-digit fishes, but I've added the multi-digit extension for my own use as "Alien Fishes" (basically truths and links written using the backslash notation -- why not because the concept is exactly the same?). With that basically any sudoku logic can be written as a fish.

[SteveG48]

I like it. Of course, now that I've got that tool, I'll probably never spot another almost fish.