The New Sudoku Players' Forum

[gurth]

Hand crafted: SER 7.2

Code: Select all

8..4.....
.....51..
.3..2157.
...1...67
.2.63..1.
........8
18.74....
.63......
25.......



[Leren]

Code: Select all

*--------------------------------------------------------------*
| 8     1     5      | 4     67    37     | 9     23    236    |
| 4-7  f47    2      | 39    69    5      | 1     8     36     |
| 9     3     6      | 8     2     1      | 5     7     4      |
|--------------------+--------------------+--------------------|
| 3     49    48     | 1     5    c489    | 2     6     7      |
| 5     2     78     | 6     3     78     | 4     1     9      |
| 6    e479   1      | 2    d79   c479    | 3     5     8      |
|--------------------+--------------------+--------------------|
| 1     8     9      | 7     4     23     | 6     23    5      |
|a47    6     3      | 5     18   b29     | 78   a49    12     |
| 2     5     47     | 39    18    6      | 78    49    13     |
*--------------------------------------------------------------*

(7=9) r8c18 - r8c6 = r46c6 - (9=7) r6c6 - r6c2 = (7) r2c2 => - 7 r2c1; stte

Leren

[ArkieTech]

Code: Select all

 *--------------------------------------------------*
 | 8    1    5    | 4    67  b37   | 9    23   236  |
 | 47   47   2    | 39   69   5    | 1    8    36   |
 | 9    3    6    | 8    2    1    | 5    7    4    |
 |----------------+----------------+----------------|
 | 3    49   48   | 1    5    489  | 2    6    7    |
 | 5    2   a78   | 6    3   b78   | 4    1    9    |
 | 6    479  1    | 2    79   479  | 3    5    8    |
 |----------------+----------------+----------------|
 | 1    8    9    | 7    4   b23   | 6    23   5    |
 |c47   6    3    | 5    18  c29   | 78  c49   12   |
 | 2    5    4-7  | 39   18   6    | 78   49   13   |
 *--------------------------------------------------*
(7=8)r5c3-(8=2)r157c6-(2=7)r8c168 => -7r9c3; ste

[gurth]

Having enjoyed Conjugate Worlds so much on the puzzle of December 18, 2014, I examined its structure and tried to create a puzzle which would give equal scope to that method - and I can promise this puzzle will not disappoint anyone trying to use that method.

[bat999]

Hi gurth
I solved this too.
I eliminated the 9 from r4c6 by asking what happens when r8c5 is not 1 and when r8c9 is not 1.
Then tidied up and repeated similar chains to remove the 9 from r6c6 (using r6c2 instead of r4c2).
(The 3 was removed from r1c9 first by using ER on box 2)

Code: Select all

.-------------.-------------.-----------------.
| 8    1    5   | 4   67   37   | 9   23  26  |
| d47  e47  2   | 39  69   5    | 1   8   36  |
| 9    3    6   | 8   2    1    | 5   7   4   |
:---------------+---------------+-------------:
| 3    f49  48  | 1   5   x48-9 | 2   6   7   |
| 5    2    78  | 6   3    78   | 4   1   9   |
| 6    479  1   | 2   79   479  | 3   5   8   |
:---------------+---------------+-------------:
| 1    8    9   | 7   4    23   | 6   23  5   |
| c47  6    3   | 5   a18  h29  | b78 49  g12 |
| 2    5    47  | 39  18   6    | 78  49  13  |
'-------------'-------------'-----------------'

[JC Van Hay]

Hi Gurth,

Just a comment about December 18 2014.

If from a=A, a -> contradiction then intermediate exclusions are useless if A -> ?.
That's why I don't waste my time to look for them.
However, if A -> solution, then, as I am never using an eraser, I can immediately see the intermediate placements.
Now, in general, the necessary intermediate placements that solve the puzzle occur either just in the same time as a contradiction, which is the case for the December 18 2014 puzzle [no place for a red 5 in R7!] or after. They very rarely occur before, at least from my own experience.

Here is a better example illustrating those points : au though October 25 2014 analysed either from r3c2=38 or from r7c8=23[or 5C3].

Best Regards, JC.

PS : just for the fun, could you test the colours transport method [from a single starting point!] on the following puzzle in order to illustrate my solution.

[SteveG48]

Code: Select all

 *--------------------------------------------------*
 | 8    1    5    | 4    67   37   | 9    23   236  |
 | 47   47   2    |a39  a6-9  5    | 1    8    36   |
 | 9    3    6    | 8    2    1    | 5    7    4    |
 *----------------+----------------+----------------|
 | 3    49   48   | 1    5    489  | 2    6    7    |
 | 5    2   c78   | 6    3    78   | 4    1    9    |
 | 6   d479  1    | 2   e79   479  | 3    5    8    |
 *----------------+----------------+----------------|
 | 1    8    9    | 7    4    23   | 6    23   5    |
 | 47   6    3    | 5    18   29   | 78   49   12   |
 | 2    5   b47   |b39   18   6    | 78  b49   13   |
 *--------------------------------------------------*


(6=3)r2c45 - (3=7)r9c348 - r5c3 = r6c2 - (7=9)r6c5 => -9 r2c5 ; stte

[gurth]

Hi JC,
Thanks for your well-meaning tips, but alas, I fear they are beyond my comprehension.
The idea of 'transport' is still a complete mystery to me, as are many other things in sudoku.
Best wishes,
Gurth.