The New Sudoku Players' Forum

[Mrfleshcage]

Ok, a stupid iPod sudoku beat me.

http://postimg.org/image/h9dhsvc0j/

Sorry but i looked through here a bit and saw a bunch
Of "b values" things. Idk what that is, but i would
Appreciate some step by steps here, if you dont mind.
Thanks!!!!

[JasonLion]

Code: Select all

.5....964467915283928364175.42.........4...27.7...63417.6.534.2...6..7..21.7.....

13    5     13    | 28    278   278   | 9     6     4   
4     6     7     | 9     1     5     | 2     8     3   
9     2     8     | 3     6     4     | 1     7     5   
------------------+-------------------+------------------
13568 4     2     | 158   3789  1789  | 568   59    689 
13568 389   1359  | 4     389   189   | 568   2     7   
58    7     59    | 258   289   6     | 3     4     1   
------------------+-------------------+------------------
7     89    6     | 18    5     3     | 4     19    2   
358   389   3459  | 6     2489  1289  | 7     1359  89   
2     1     3459  | 7     489   89    | 568   359   689 

That is a rather complex puzzle for an app (though not by forum standards). I see a couple of XY-Wings, followed by a pair of ALS-XZs and singles to the end.

[ArkieTech]

I call this a Hybrid-wing:

Code: Select all

 *--------------------------------------------------------------------*
 | 13     5      13     |b28     278   c278    | 9      6      4      |
 | 4      6      7      | 9      1      5      | 2      8      3      |
 | 9      2      8      | 3      6      4      | 1      7      5      |
 |----------------------+----------------------+----------------------|
 | 13568  4      2      | 158    3789   1789   | 568    59     689    |
 | 13568  389    1359   | 4      389    189    | 568    2      7      |
 | 58     7      59     | 258    289    6      | 3      4      1      |
 |----------------------+----------------------+----------------------|
 | 7      89     6      |a18     5      3      | 4      19     2      |
 | 358    389    3459   | 6      2489  d289-1  | 7      1359   89     |
 | 2      1      3459   | 7      489    89     | 568    359    689    |
 *--------------------------------------------------------------------*
(1=8)r7c4-(8=2)r1c4-r1c6=2r8c6 => -1r8cf6; ste

[StrmCkr]

its easier then jason suggests

Code: Select all

.------------------.-----------------.----------------.
| 13     5    13   | 28   278   278  | 9    6     4   |
| 4      6    7    | 9    1     5    | 2    8     3   |
| 9      2    8    | 3    6     4    | 1    7     5   |
:------------------+-----------------+----------------:
| 13568  4    2    | 18-5 3789  1789 | 568  59    689 |
| 13568  389  1359 | 4    389   189  | 568  2     7   |
| 58     7    59   | 258  289   6    | 3    4     1   |
:------------------+-----------------+----------------:
| 7      89   6    | 18   5     3    | 4    19    2   |
| 358    389  3459 | 6    2489  1289 | 7    1359  89  |
| 2      1    3459 | 7    489   89   | 568  359   689 |
'------------------'-----------------'----------------'

from the above state

hybrid wing (type 1): 5 r4c4 -5- r4c8 -9- r7c8 -1- r7c4 =1= r4c4 => r4c4<>5
reduces the grid to all singles to the end.

[Mrfleshcage]

I looked up some of your stuff, but i need explanations, like 1+1 = 2

A link would help! And thanks for reply but i dont know what your numbers mean...

[StrmCkr]

Code: Select all

.------------------.-----------------.----------------.
| 13     5    13   | 28   278   278  | 9    6     4   |
| 4      6    7    | 9    1     5    | 2    8     3   |
| 9      2    8    | 3    6     4    | 1    7     5   |
:------------------+-----------------+----------------:
| 13568  4    2    | 185 3789  1789 | 568  59    689 |
| 13568  389  1359 | 4    389   189  | 568  2     7   |
| 58     7    59   | 258  289   6    | 3    4     1   |
:------------------+-----------------+----------------:
| 7      89   6    | 18   5     3    | 4    19    2   |
| 358    389  3459 | 6    2489  1289 | 7    1359  89  |
| 2      1    3459 | 7    489   89   | 568  359   689 |
'------------------'-----------------'----------------'

look at the cells R4C4 and R7C4 both cells contain the digit "1" these represent a strong link {= sign in our notation} ie if one is false the opposite must be true.

the cells R4C4 and R4C8 contain the the digit 5 as weak link { - sign in our notation, based on position and digit counts for row, either or location can be false and only one could be true}

cells R4C8 is a bivalve cell of digits 5 and 9, if a cell in its line of sight contains 5 or 9 then the remaining candidate must be true

cell R7C8 is also a bivalve cell of digits 1 and 9, if a cell in its line of sight contains 1 or 9 then the remainder must be true.

cell R7C4 is also a bivalve but its only relation ship we need to know is the strong link on digit 1 using col 4.


i set up a chain relation ship between these cells and the digits ( 1,5,9 ): creating these when you iterate all possibles and note the same elimination contain from all iterations : R4C4 <> 5

Code: Select all

R4c4 = 1  =>>it cannot contain digit 5
R4C4 = 5  => R4C8 = 9 => R8C8 = 1 => R7C4  = 8   => R4c4 = 1   {a contradiction}
R4C8 = 5 =>> R4c4 <> 5
r4c8 = 9 => R4C8 = 9 => R7C8 = 1 => R7C4  = 8   => R4c4 = 1  =>> R4c4 <> 5
R7C8 = 9 => R4C8 = 5  =>> R4C4 <>5
R7C8 = 1 => R7C4  = 8   => R4c4 = 1  =>> R4C4 <>5
R7C4 = 1 => R7C8 = 9 => R4C8 = 5 =>> R4C4 <> 5
R7C4 = 8  =>R4C4 = 1 =>> R4C4 <> 5

to read the chain as noted:

placing 5 in R4C4 - {implies it weak link cannot contain} 5 - R4C4 - {implies its weak link cannot contain} 9 - R7C8 - {implies its weak link cannot contain digit} 1 - R7C4 = {implies its strong link must contain digit} 1 = R4C4 =>> implies R4C4 <> contain digit 5 based on the contradiction the chain shows to exist. R4C4 cannot be both 5 and 1 at the same time.

hope that makes sense.

[Pat]

i need explanations

look at ArkieTech's diagram

Code: Select all

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


consider this stream of implications —

if r8c6 = 1
then

r7c4 = 8 ("naked single"),
r1c4 = 2 ("naked single"),
r8c6 = 2 ("hidden single" in column),
r8c6 not 1

A link would help

"forcing chains"
and "forcing nets"
— see discussed at:
Forcing chains: Terminology and Definition
( heavy reading ! )

[PDN]

Hi,

Another thing you can do is plug your puzzle into this online solver:

http://www.sudokuwiki.org/sudoku.htm

Not only is it amazing, but Andrew Stuart has very clear
explanations of the complex techniques used.

--Prahas