## How hard is this puzzle?

Everything about Sudoku that doesn't fit in one of the other sections
ravel wrote:To be more precise, the "Strong link of 1s in r5c78 => UR-type 4" doesn't exist here.

Thanks ravel... It's my turn to be blind...
udosuk

Posts: 2698
Joined: 17 July 2005

Ravel wrote:If you remove the 2 in r9c1 instead, you get a harder one:

Code: Select all
` *------------------------------------------------------------* | 3678   5      4   | 389    2      79  | 1378   13789  3689 | | 3678   2      9   | 348    47     1   | 378    5      368  | | 378    378    1   | 389    5      6   | 4      23789  2389 | |-------------------+-------------------+--------------------| | 1      37     5   | 49     47     8   | 237    6      239  | | 4      678    267 | 5      3      279 | 178    1789   89   | | 2378   9      237 | 16     16     27  | 5      378    4    | |-------------------+-------------------+--------------------| | 59     346    236 | 126    169    45  | 368    38     7    | | 59     346    8   | 7      69     45  | 236    23     1    | | 27     1      267 | 26     8      3   | 9      4      5    | *------------------------------------------------------------*`

1. [r3c2]=8=[r5c2]-8-[r6c1]=8=[r6c8]-8-[r7c8]-3-[r7c3]=3=[r6c3](-3-
-[r6c1])-3-[r4c2]-7-[r4c2], => r4c2<>7, r6c1<>3.

2. [r4c5]-7-[r4c2]-3-[r6c3]-2-[r6c6]-7-[r4c5], => r4c5<>7.

Carcul
Carcul

Posts: 724
Joined: 04 November 2005

Is it possible to remove both the 2 in r9c1 and the 1 in r4c1 and still get a puzzle with a unique solution?

(I was going to post this much earlier but due to "circumstances beyond my control" I was unable to access this site then.)
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Once upon a time I was a teenager who was active on here 2007-2011
999_Springs

Posts: 367
Joined: 27 January 2007
Location: In the toilet, flushing down springs, one by one.

No, there are 3 minimal puzzles, without 9 in r1c6 and 2 in r9c1, without 9 in r1c6 and 9 in r9c7 and without 1 in r4c1.

I calculate them using gsf's program, where i have a batch file (i called it gsfmin.bat) with this text, entered in notepad:
sudoku -m puzzles.txt > min.txt
When i copy the puzzle(s) to puzzles.txt (in the directory of gsf's program and the batch file), i only need to doubleclick the batch file in the explorer to get the minimals in min.txt.
ravel

Posts: 998
Joined: 21 February 2006

post deleted
Last edited by ArkieTech on Sat Mar 03, 2007 12:18 am, edited 1 time in total.
dan

ArkieTech

Posts: 2619
Joined: 29 May 2006
Location: NW Arkansas USA

ArkieTech wrote:Single [R7C2]= 6
ravel

Posts: 998
Joined: 21 February 2006

These eliminations are not supported by the contents of the grid when they occur.

Code: Select all
`ColBox [R7C2]<> 6ColBox [R8C2]<> 6 *--------------------------------------------------------------------* | 3678   5      4      | 389    2      79     | 1378   13789  3689   | | 3678   2      9      | 348    478    1      | 378    5      368    | | 378    378    1      | 389    5      6      | 4      23789  2389   | |----------------------+----------------------+----------------------| | 1      37     5      | 249    479    8      | 237    6      239    | | 4     *678   *267    | 5      3      279    | 1278   12789  289    | | 2378   9      237    | 126    167    27     | 5      2378   4      | |----------------------+----------------------+----------------------| | 2359   34-6  *236    | 1269   169    2459   | 2368   238    7      | | 2359   34-6   8      | 7      69     2459   | 236    23     1      | | 27     1     *267    | 268    68     3      | 9      4      5      | *--------------------------------------------------------------------*`
daj95376
2014 Supporter

Posts: 2624
Joined: 15 May 2006

ravel said:

daj95376 said:
These eliminations are not supported by the contents of the grid when they occur.

OOPs My boo boo I will delete my post.

Hope this is right
Code: Select all
`*-----------*|.5.|.2.|...||.29|..1|.5.||...|..6|4..||---+---+---||1.5|..8|.6.||4..|53.|...||.9.|...|..4||---+---+---||...|...|..7||..8|7..|..1||.1.|..3|9..|*-----------**--------------------------------------------------------------------------*| 3678    5       13467  | 3489    2       479    | 13678   13789   3689   || 3678    2       9      | 348     478     1      | 3678    5       368    || 378     378     137    | 389     5789    6      | 4       123789  2389   ||------------------------+------------------------+------------------------|| 1       37      5      | 249     479     8      | 237     6       239    || 4       678     267    | 5       3       279    | 1278    12789   289    || 23678   9       2367   | 126     167     27     | 123578  12378   4      ||------------------------+------------------------+------------------------|| 23569   346     2346   | 124689  145689  2459   | 23568   2348    7      || 23569   346     8      | 7       4569    2459   | 2356    234     1      || 2567    1       2467   | 2468    4568    3      | 9       248     2568   |*--------------------------------------------------------------------------*Hidden Single  [R3C5]=5 RowHidden Single  [R6C7]=5 RowHidden Single  [R9C9]=5 ColHidden Single  [R1C3]=4 BoxHidden Single  [R3C3]=1 ColBoxCol [R9C1]<> 6BoxRow [R6C8]<> 1BoxRow [R6C3]<> 6BoxCol [R7C1]<> 6BoxCol [R2C7]<> 6ColBox [R7C4]<> 4ColBox [R9C4]<> 4ColBox [R7C5]<> 4ColBox [R8C5]<> 4ColBox [R9C5]<> 4Hidden Single  [R9C8]=4 RowBoxCol [R7C4]<> 6BoxCol [R2C5]<> 8Then it takes trips *--------------------------------------------------------------------* | 3678   5      4      | 389    2      79     | 1378   13789  3689   | | 3678   2      9      | 348    478    1      | 378    5      368    | | 378    378    1      | 389    5      6      | 4      23789  2389   | |----------------------+----------------------+----------------------| | 1      37     5      | 249    479    8      | 237    6      239    | | 4      678    267    | 5      3      279    | 1278   12789  289    | | 2378   9      237    | 126    167    27     | 5      2378   4      | |----------------------+----------------------+----------------------| | 2359   346    236    | 1269   169    2459   | 2368   238    7      | | 2359   346    8      | 7      69     2459   | 236    23     1      | | 27     1      267    | 268    68     3      | 9      4      5      | *--------------------------------------------------------------------*`
dan

ArkieTech

Posts: 2619
Joined: 29 May 2006
Location: NW Arkansas USA

I want to know what this puzzle rating in ER and its content. Thanks.
Code: Select all
` 4 . . | 2 . . | 3 . . . . 7 | . . 8 | . . 4 . 8 . | . 6 . | . 5 .-------+-------+------- 2 . . | . . . | 5 . . . . 1 | . . . | . . 7 . 6 . | . . . | . 9 .-------+-------+------- 3 . . | 7 . . | . . . . . 8 | . . 2 | . . 3 . 5 . | . 9 . | . 1 .`
Eioru

Posts: 182
Joined: 16 August 2006

Eioru wrote:I want to know what this puzzle rating in ER and its content. Thanks.