The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|...|65.|
 |.63|4..|.9.|
 |1..|.3.|..7|
 |---+---+---|
 |48.|3.5|...|
 |...|.8.|...|
 |...|9.1|.75|
 |---+---+---|
 |8..|.2.|..9|
 |.4.|..3|58.|
 |.21|...|...|
 *-----------*


Play/Print this puzzle online

[pjb]

Code: Select all

 *27      79      4      | 1278   179  b*2789  | 6      5      3     
a*257     6       3      | 4      7-5   *27     | 1      9      8     
  1       9-5     8      |d56     3     c69     | 24     24     7     
 ------------------------+----------------------+---------------------
  4       8       79     | 3      67     5      | 29     26     1     
  579     1       579    | 267    8      267    | 49     3      46     
  6       3       2      | 9      4      1      | 8      7      5     
 ------------------------+----------------------+---------------------
  8       57      567    | 67     2      4      | 3      1      9     
  79      4       679    | 167    167    3      | 5      8      2     
  3       2       1      | 58     59    b89     | 7      46     46     


Using DP (27) r12c16: (5)r2c1 = (89)r1c6
(5)=(89)DP,(89)r9c6 - (9=6)r3c6 - (6=5)r3c4 => -5 r2c5, r3c2; stte

Phil

[SteveG48]

XY-wing 567, pivot r7c4, wings r3c4,r7c2 => -5 r3c2 ; stte

[Leren]

Same as Steve.

Leren

[Marty R.]

XY-wing 567, pivot r7c4, wings r3c4,r7c2 => -5 r3c2 ; stte

Code: Select all

+------------+---------------+----------+
| 27  79 4   | 1278 179 2789 | 6  5  3  |
| 257 6  3   | 4    57  27   | 1  9  8  |
| 1   59 8   | 56   3   69   | 24 24 7  |
+------------+---------------+----------+
| 4   8  79  | 3    67  5    | 29 26 1  |
| 579 1  579 | 267  8   267  | 49 3  46 |
| 6   3  2   | 9    4   1    | 8  7  5  |
+------------+---------------+----------+
| 8   57 567 | 67   2   4    | 3  1  9  |
| 79  4  679 | 167  167 3    | 5  8  2  |
| 3   2  1   | 58   59  89   | 7  46 46 |
+------------+---------------+----------+


Play this puzzle online at the Daily Sudoku site

Like Steve, I went after the low-hanging fruit.

[Marty R.]

Code: Select all

+------------+---------------+----------+
| 27  79 4   | 1278 179 2789 | 6  5  3  |
| 257 6  3   | 4    57  27   | 1  9  8  |
| 1   59 8   | 56   3   69   | 24 24 7  |
+------------+---------------+----------+
| 4   8  79  | 3    67  5    | 29 26 1  |
| 579 1  579 | 267  8   267  | 49 3  46 |
| 6   3  2   | 9    4   1    | 8  7  5  |
+------------+---------------+----------+
| 8   57 567 | 67   2   4    | 3  1  9  |
| 79  4  679 | 167  167 3    | 5  8  2  |
| 3   2  1   | 58   59  89   | 7  46 46 |
+------------+---------------+----------+


Play this puzzle online at the Daily Sudoku site

Also, DP (79)r58c13. 6r8c3=9r5c13-(9=4)r5c7-(4=6)r5c9-r5c6=r3c6=> -6r3c4
How do I finish? I want to show the 1st 6 branching off at the start 6r8c3-r7c3=r7c4. I tried a pipe below the 6 but couldn't get it to align.

[eleven]

Just to apply blues' hint (take the externals of r2 and c6 here):
DP (27) r12c16: 7r2c5=27r5c6
7r2c5=(27-6)r5c6=6r3c6-(6=57)r3c4,r2c5 => r2c5=7

[eleven]

Also, DP (79)r58c13. 6r8c3=9r5c13-(9=4)r5c7-(4=6)r5c9-r5c6=r3c6=> -6r3c4
How do I finish? I want to show the 1st 6 branching off at the start 6r8c3-r7c3=r7c4. I tried a pipe below the 6 but couldn't get it to align.

So start with it:
DP (79)r58c13: 6r8c3=9r5c13
6r7c4=6r7c3-6r8c3=9r5c13-(9=4)r5c7-(4=6)r5c9-r5c6=r3c6=> -6r3c4
or
DP (79)r58c13: 6r8c3=9r5c13
6r7c4=6r7c3-6r8c3=DP=9r5c13-(9=4)r5c7-(4=6)r5c9-r5c6=r3c6=> -6r3c4
or
6r7c4=6r7c3-6r8c3=DP(79)r58c13=9r5c13-(9=4)r5c7-(4=6)r5c9-r5c6=r3c6=> -6r3c4
...

[bat999]

Code: Select all

.---------------.-------------------.------------.
| 27    79  4   |  1278   179  2789 | 6   5   3  |
| 257   6   3   |  4      57   27   | 1   9   8  |
| 1    b59  8   | c5-6    3    69   | 24  24  7  |
:---------------+-------------------+------------:
| 4     8   79  |  3      67   5    | 29  26  1  |
| 579   1   579 |  267    8    267  | 49  3   46 |
| 6     3   2   |  9      4    1    | 8   7   5  |
:---------------+-------------------+------------:
| 8    a57  567 | a67     2    4    | 3   1   9  |
| 79    4   679 |  167    167  3    | 5   8   2  |
| 3     2   1   |  58     59   89   | 7   46  46 |
'---------------'-------------------'------------'

(6=5)r7c24 - r3c2 = (5)r3c4 => -6 r3c4; stte

[ArkieTech]

XY-wing 567, pivot r7c4, wings r3c4,r7c2 => -5 r3c2 ; stte

Code: Select all

+------------+---------------+----------+
| 27  79 4   | 1278 179 2789 | 6  5  3  |
| 257 6  3   | 4    57  27   | 1  9  8  |
| 1   59 8   | 56   3   69   | 24 24 7  |
+------------+---------------+----------+
| 4   8  79  | 3    67  5    | 29 26 1  |
| 579 1  579 | 267  8   267  | 49 3  46 |
| 6   3  2   | 9    4   1    | 8  7  5  |
+------------+---------------+----------+
| 8   57 567 | 67   2   4    | 3  1  9  |
| 79  4  679 | 167  167 3    | 5  8  2  |
| 3   2  1   | 58   59  89   | 7  46 46 |
+------------+---------------+----------+


Play this puzzle online at the Daily Sudoku site

Like Steve, I went after the low-hanging fruit.

Sorry about that! I like puzzles with no low hanging fruit. Missed this one.

[Marty R.]

Just to apply blues' hint (take the externals of r2 and c6 here):
DP (27) r12c16: 7r2c5=27r5c6
7r2c5=(27-6)r5c6=6r3c6-(6=57)r3c4,r2c5 => r2c5=7

Thank you. Are we talking about the same puzzle? I don't see a post by blue here and I'd better go back to DPs 101 because I don't understand how these cells relate to the DP.

[eleven]

It was in yesterdays puzzle thread, see here.

Code: Select all

+------------+---------------+----------+
|*27  79 4   | 1278 179*2789 | 6  5  3  |
|*257 6  3   | 4   #57 *27   | 1  9  8  |
| 1   59 8   | 56   3   69   | 24 24 7  |
+------------+---------------+----------+
| 4   8  79  | 3    67  5    | 29 26 1  |
| 579 1  579 | 267  8  #267  | 49 3  46 |
| 6   3  2   | 9    4   1    | 8  7  5  |
+------------+---------------+----------+
| 8   57 567 | 67   2   4    | 3  1  9  |
| 79  4  679 | 167  167 3    | 5  8  2  |
| 3   2  1   | 58   59  89   | 7  46 46 |
+------------+---------------+----------+

Here yo can see, that
if there is no 7 in r2c5 (the external of row 2), r2c16 are the only cells for 27 in r2 (i.e. r2c1 is 27),
and if there is none of 27 in r5c6 (the externals of column 6), 27 can only go to r12c6 in c6 (i.e. r1c6 is 27).
So to avoid the DP, one of these externals must be true.
(Same for the externals of c1+r1,b1+r1,c1+b2, b1c6,r2+b2,r2+c6 and the "usual" c1+c6,r1+r2,b1+b2, but they seem to be less useful - and of course you can combine the externals of one side with the internals of the other)

[Ngisa]

Code: Select all

+------------+---------------+----------+
| 27  79 4   | 1278 179 2789 | 6  5  3  |
| f257 6  3   | 4    57  27   | 1  9  8  |
| 1   e59 8   | d56   3   69   | 24 24 7  |
+------------+---------------+----------+
| 4   8  79  | 3    67  5    | 29 26 1  |
| 79-5 1 a579 | 267  8   267  | 49 3  46 |
| 6   3  2   | 9    4   1    | 8  7  5  |
+------------+---------------+----------+
| 8   57 b567 | c67   2   4    | 3  1  9  |
| 79  4  679 | 167  167 3    | 5  8  2  |
| 3   2  1   | 58   59  89   | 7  46 46 |
+------------+---------------+----------+


(5)r5c3=(5-6)r7c3=r7c4-(6=5)r3c4-r3c2=(5)r2c1 => -5r5c1; stte

Clement