The New Sudoku Players' Forum

[mw210461]

Ok, they warned it would be 'very difficult' (offering 3 easier ones to start with). Eagerly I started to pluck at it, and 'ouch'...

Code:
.....84.6
.2..9..53
.........
.....4...
....739..
6.9.1..7.
7.3.....9
861...2..
..23...6.
End Code

Way above my horizon.

Got it down to:

Code:
.....84.6
.2..9..53
.........
...9.46..
...6739..
6.9.1.37.
7.3.....9
861..923.
..23...6.
End Code

plus some extra reduction of candidates, but that was "it".
I found the Swiss program "Sudoku Explainer" very useful and informative, it usually leads into the proper direction.
Its 'rating' tells me that I am a sub "2.8" player in general, maybe with potential for more in the future?
I have to admit though that hunting such an obscure "Turbot Fish" X chain is something I do NOT really enjoy.
C'mon: if you want to check all the possible chains (that's TRYING for me, not really REASONING!) for all empty cells, how long will such an exercise take you on average, with 50 empty cells to go?
How deep is such trial and error approach reasonable? How much different is this method from simple "guess hunting" down whenever ambiguous paths appear, until it fails?

I am afraid I am a little league player only - so YOU enjoy this one!

michael

[daj95376]

There are several names for the pattern that generates the elimination you need. I hope you find mine more acceptable than the one from SE.

Code: Select all

 +-----------------------+
 | . . . | . . 8 | 4 . 6 |
 | . 2 . | . 9 . | . 5 3 |
 | . . . | . . . | . . . |
 |-------+-------+-------|
 | . . . | . . 4 | . . . |
 | . . . | . 7 3 | 9 . . |
 | 6 . 9 | . 1 . | . 7 . |
 |-------+-------+-------|
 | 7 . 3 | . . . | . . 9 |
 | 8 6 1 | . . . | 2 . . |
 | . . 2 | 3 . . | . 6 . |
 +-----------------------+

   c9b6  Locked Candidate 1              <> 5    [r89c9]
 r8  b8  Locked Candidate 2              <> 5    [r7c456],[r9c56]

 *--------------------------------------------------------------------------------------*
 | 1359     13579    57       | 1257     235      8        | 4        129      6        |
 | 14       2        4678     | 147      9        167      | 178      5        3        |
 | 13459    1345789  45678    | 12457    23456    12567    | 178      1289     1278     |
 |----------------------------+----------------------------+----------------------------|
 | 1235     13578    578      | 9        258      4        | 6        128      1258     |
 | 1245     1458     458      | 6        7        3        | 9        1248     12458    |
 | 6       *458      9        | 258      1        25       | 3        7       *2458     |
 |----------------------------+----------------------------+----------------------------|
 | 7        5-4      3        | 1248     2468     126      | 158     *148      9        |
 | 8        6        1        | 457      45       9        | 2        3       *47       |
 | 459      459      2        | 3        48       17       | 1578     6       *1478     |
 *--------------------------------------------------------------------------------------*

 r6  b9  Empty Rectangle                 <> 4    [r7c2]

 r9  b7  Naked  Pair                     <> 49   [r9c5]
   c3    Naked  Triple                   <> 578  [r23c3]