The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |..3|..2|...|
 |.6.|...|82.|
 |.4.|.7.|..6|
 |---+---+---|
 |8..|2.7|...|
 |..9|...|1..|
 |...|5.6|..7|
 |---+---+---|
 |1..|.6.|.5.|
 |.85|...|.9.|
 |...|1..|3..|
 *-----------*


Play/Print this puzzle online

[eleven]

Code: Select all

 *--------------------------------------------------------*
 | 59   15    3    | 6     8    2      | 4579  147 e459   |
 | 579  6    d17   | 349   345 c13459  | 8     2   *359   |
 | 2    4     8    | 39    7   b1359   |*59   a13   6     |
 |-----------------+-------------------+------------------|
 | 8    15    6    | 2     19   7      | 459   34   3459  |
 |h57   27    9    | 348   34   348    | 1     6   g25    |
 | 34   23    124  | 5     19   6      | 29    8    7     |
 |-----------------+-------------------+------------------|
 | 1    2379  247  | 3489  6    3489   | 247   5   f248   |
 | 34   8     5    | 7     2    34     | 6     9    1     |
 | 6    279   247  | 1     45   4589   | 3     47  f248   |
 *--------------------------------------------------------*

r2c9=3->r3c8=1->r2c6=1->r3c3=7 [edit: corrected, thanks to Marty]
r2c9<>3->r1c9=4->r79c9=28->r5c9=5->r5c1=7
=>r2c1<>7

[SudoQ]

A contradiction network (r4):

Code: Select all

|----------------|------------------|-----------------|
| 59  (15)   3   | 6     8    2     | 4579  47-1 459  |
| 579  6     17  | 349   345  13459 | 8     2    359  |
| 2    4     8   |(39)   7    1359  |(59)  (13)  6    |
|----------------|------------------|-----------------|
| 8    1(5)  6   | 2     19   7     |4(5)9 (3)4 (35)49|
| 57   27    9   | 348   34   348   | 1     6    25   |
| 34   23    124 | 5     19   6     | 29    8    7    |
|----------------|------------------|-----------------|
| 1    2379  247 | 3489  6    3489  | 247   5    248  |
| 34   8     5   | 7     2    34    | 6     9    1    |
| 6    279   247 | 1     45   4589  | 3     47   248  |
|----------------|------------------|-----------------|

/SudoQ

[eleven]

Can be seen also as: all 5's in row 4 eliminate 1 in r1c8.

[ArkieTech]

Code: Select all

 *--------------------------------------------------------------------*
 |b59    b15     3      | 6      8      2      | 4579   147   b459    |
 | 579    6      17     | 349    345    13459  | 8      2      359    |
 | 2      4      8      | 39     7      1359   | 59     13     6      |
 |----------------------+----------------------+----------------------|
 | 8     a15     6      | 2      19     7      | 49-5   34     349-5  |
 | 7-5    27     9      | 348    34     348    | 1      6     c25     |
 | 34     23     124    | 5      19     6      | 29     8      7      |
 |----------------------+----------------------+----------------------|
 | 1      2379   247    | 3489   6      3489   | 247    5     c248    |
 | 34     8      5      | 7      2      34     | 6      9      1      |
 | 6      279    247    | 1      45     4589   | 3      47    c248    |
 *--------------------------------------------------------------------*
als xy-wing
(5=1)r4c2-(1=4)r1c129-(4=5)r579c9 => -5r4c79,r5c1; stte

[SudoQ]

Can be seen also as: all 5's in row 4 eliminate 1 in r1c8.

Is there a better syntax to show it than like this?

Code: Select all

r4c2=5 -> r1c2=1                     =>
  c7   -> r3c7=9 -> r3c4=3 -> r3c8=1 =>
  c9   -> r4c8=3 -> r3c8=1           => r1c8<>1

/SudoQ

[eleven]

Is there a better syntax to show it than like this?

Code: Select all

r4c2=5 -> r1c2=1                     =>
  c7   -> r3c7=9 -> r3c4=3 -> r3c8=1 =>
  c9   -> r4c8=3 -> r3c8=1           => r1c8<>1

There is a sis-notation for Eureka friends, but i don't know, how to write it. Maybe someone can help out.

als xy-wing
(5=1)r4c2-(1=4)r1c129-(4=5)r579c9 => -5r4c79,r5c1; stte

Nice. I did not notice the 4(59) in row 1 - saw the 3(59) before.
Do you really scan a puzzle for pairs of n-digit ALS's with common candidates ?

[tlanglet]

Several variation of this logic....

(1=5)r1c2-(5=1=9)r4c25-r4c79=r6c7-(59=4)r34c7-(4=3=1)r43c8 => r1c8<>1

[ArkieTech]

Do you really scan a puzzle for pairs of n-digit ALS's with common candidates ?

I find many puzzles are solved with the als xy-wing model using pseudo cells. I check als's containing two of the numbers needed in the pseudo cell. Not finding one that will work I have started looking for two. I also use various software tools when I get stuck. Believe it or not I have been helped greatly in finding them by simplifing thier Eureka notation. Getting rid of clutter helps me a lot.

[eleven]

I don't quite understand, what you mean with pseudo cells. I saw that Marty used this term for 2 or 3 cells in a DP, which have to contain 1 of 2 or 2 of 3 candidates. Could you show in your xy-wing please, what is meant ?

[Marty R.]

Code: Select all

+--------------+----------------+---------------+
| 59  15   3   | 6    8   2     | 4579 147 459  |
| 579 6    17  | 349  345 13459 | 8    2   359  |
| 2   4    8   | 39   7   1359  | 59   13  6    |
+--------------+----------------+---------------+
| 8   15   6   | 2    19  7     | 459  34  3459 |
| 57  27   9   | 348  34  348   | 1    6   25   |
| 34  23   124 | 5    19  6     | 29   8   7    |
+--------------+----------------+---------------+
| 1   2379 247 | 3489 6   3489  | 247  5   248  |
| 34  8    5   | 7    2   34    | 6    9   1    |
| 6   279  247 | 1    45  4589  | 3    47  248  |
+--------------+----------------+---------------+


Play this puzzle online at the Daily Sudoku site

Don't know what to call it.

(2=9)r6c7-(9=54)r34c7-(4=3)r4c8-(3=1)r3c8-r1c8=r1c2-(1=5)r4c2-(5=7)r5c1-(7=2)r5c2=>r5c9,r6c2<>2

[Marty R.]

r2c9=3->r3c8=1->r2c6=1->r3c5=7
r2c9<>3->r1c9=4->r79c9=28->r5c9=5->r5c1=7
=>r2c1<>7

Eleven, is that a typo at the end of line 1, as in, should be r3c3?

[Leren]

Code: Select all

*--------------------------------------------------------------------------------*
|b59     b15      3        | 6       8       2        | 4579    147    b459      |
| 579     6       17       | 349     345     13459    | 8       2       359      |
| 2       4       8        | 39      7       1359     | 59      13      6        |
|--------------------------+--------------------------+--------------------------|
| 8      a15      6        | 2       19      7        | 459     34      3459     |
|a57     a27      9        | 348     34      348      | 1       6       5-2      |
| 34      23      124      | 5       19      6        | 29      8       7        |
|--------------------------+--------------------------+--------------------------|
| 1       2379    247      | 3489    6       3489     | 247     5      c248      |
| 34      8       5        | 7       2       34       | 6       9       1        |
| 6       279     247      | 1       45      4589     | 3       47     c248      |
*--------------------------------------------------------------------------------*

Another als xy-wing: (2=1) r5c12,r4c2 - (1=4) r1c129 - (4=2) r79c9 => r5c9 <> 2; stte

Leren

[eleven]

Eleven, is that a typo at the end of line 1, as in, should be r3c3?

Yes, thanks. I corrected it.

Another als xy-wing: (2=1) r5c12,r4c2 - (1=4) r1c129 - (4=2) r79c9 => r5c9 <> 2; stte
Leren

Ah, i thought it was a chain, but as notated it looks like an xy-wing.

btw in the morning i had found an als xz without knowing it. It was the chain
(5=9)r3c7-(9=3)r3c4-r2c345=r2c9; r2c9<>5 (does not solve the puzzle)
As a pattern:
als xz (5=39)r3c46-(3=14579)r2c13456; r2c9<>5

[Leren]

eleven wrote: (5=9)r3c7-(9=3)r3c4-r2c345=r2c9; r2c9<>5 (does not solve the puzzle)

There is an ordinary xy wing (259) r36c7, r5c9 => r12c9, r4c7 <> 5 but this still doesn't solve the puzzle

Leren