The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|2..|.81|
 |6..|...|...|
 |..4|1..|6..|
 |---+---+---|
 |.3.|..7|..9|
 |5..|.4.|..8|
 |1..|3..|.2.|
 |---+---+---|
 |..6|..8|7..|
 |...|...|..5|
 |92.|..5|...|
 *-----------*


Play/Print this puzzle online

[Leren]

Code: Select all

*-----------------------------------------------------------------------*
| 37     79     3579    | 2      5679   3469    | 349    8      1       |
| 6      1789   123578  | 58     5789   349     | 2349   34579  2347    |
| 2378   789    4       | 1      5789   39      | 6      3579   237     |
|-----------------------+-----------------------+-----------------------|
| 248    3      28      | 58     12     7       | 145    6      9       |
| 5      679    279     |b69     4      12      | 13     137    8       |
| 1     d46789  789     | 3      58    c69      | 45     2      47      |
|-----------------------+-----------------------+-----------------------|
| 3-4    5      6       |a49     1239   8       | 7      1349   234     |
| 3478  e1478   1378    | 679-4  12369  12      | 123489 1349   5       |
| 9      2      1378    | 47     13     5       | 1348   134    6       |
*-----------------------------------------------------------------------*

(4=9) r7c4 - r5c4 = (9-6) r6c6 = (6-4) r6c2 = (4) r8c2 => - 4 r7c1, r8c4; lclste

Leren

[ArkieTech]

Code: Select all

*-----------------------------------------------------------------------*
| 37     79     3579    | 2      5679   3469    | 349    8      1       |
| 6      1789   123578  | 58     5789   349     | 2349   34579  2347    |
| 2378   789    4       | 1      5789   39      | 6      3579   237     |
|-----------------------+-----------------------+-----------------------|
| 248    3      28      | 58     12     7       | 145    6      9       |
| 5      679    279     |b69     4      12      | 13     137    8       |
| 1     d46789  789     | 3      58    c69      | 45     2      47      |
|-----------------------+-----------------------+-----------------------|
| 3-4    5      6       |a49     1239   8       | 7      1349   234     |
| 3478  e1478   1378    | 679-4  12369  12      | 123489 1349   5       |
| 9      2      1378    | 47     13     5       | 1348   134    6       |
*-----------------------------------------------------------------------*

(4=9) r7c4 - r5c4 = (9-6) r6c6 = (6-4) r6c2 = (4) r8c2 => - 4 r7c1, r8c4; lclste

Leren

als m-wing?
(4=6)r57c4-r5c2=(6-4)r6c2=4r8c2 => -4r7c1,r8c4; lclste

[Marty R.]

Code: Select all

+-------------------+-----------------+-------------------+
| 37   79    3579   | 2    5679  3469 | 349    8     1    |
| 6    1789  123578 | 58   5789  349  | 2349   34579 2347 |
| 2378 789   4      | 1    5789  39   | 6      3579  237  |
+-------------------+-----------------+-------------------+
| 248  3     28     | 58   12    7    | 145    6     9    |
| 5    679   279    | 69   4     12   | 13     137   8    |
| 1    46789 789    | 3    58    69   | 45     2     47   |
+-------------------+-----------------+-------------------+
| 34   5     6      | 49   1239  8    | 7      1349  234  |
| 3478 1478  1378   | 4679 12369 12   | 123489 1349  5    |
| 9    2     1378   | 47   13    5    | 1348   134   6    |
+-------------------+-----------------+-------------------+


Play this puzzle online at the Daily Sudoku site

Elimination of the same 4.

4r8c2=(4-6)r6c2=r6c6-(6=9)r5c4-(9=4)r7c4=>r7c1<>4

[daj95376]

_

My solver found three chains to crack this puzzle ... and they were essentially equivalent.

Code: Select all

 +-----------------------------------------------------------------------------------------+
 |  37       79       3579     |  2        5679     3469     |  349      8        1        |
 |  6        1789     1235789  |  58       5789     349      |  2349     34579    2347     |
 |  2378     789      4        |  1        5789     39       |  6        3579     237      |
 |-----------------------------+-----------------------------+-----------------------------|
 | G248      3        28       |  58       12       7        |  145      6        9        |
 |  5       e679      279      | d69       4        12       |  13       137      8        |
 |  1       f46789    789      |  3        58       69       |  45       2        47       |
 |-----------------------------+-----------------------------+-----------------------------|
 | b34       5        6        | c49       1239     8        |  7        1349     234      |
 | a3478    a1478g    1378     |  4679     12369    12       |  123489   1349     5        |
 |  9        2        1378     |  47       13       5        |  1348     134      6        |
 +-----------------------------------------------------------------------------------------+
 # 123 eliminations remain

                        c           d      e           f         G
                   (4=9)r7c4 - (9=6)r5c4 - r5c2 = (6-4)r6c2 = (4)r4c1  =>  r7c1<>4
                        c           d      e           f         g
                   (4=9)r7c4 - (9=6)r5c4 - r5c2 = (6-4)r6c2 = (4)r8c2  =>  r7c1,r8c4<>4
    a       b           c           d      e           f         g
 (4)r8c12 = r7c1 - (4=9)r7c4 - (9=6)r5c4 - r5c2 = (6-4)r6c2 = (4)r8c2  =>  r8c478<>4


[SteveG48]

Code: Select all

.----------------------.-------------------.---------------------.
| 37    79     bc3579  | 2   bd5679  be3469| aL349    8     1    |
| 6     1789   1235789 | 58    5789   349  | 2349    4579  k2347 |
| 2378  789    4       | 1     5789   39   | 6       3579  k237  |
:----------------------+-------------------+---------------------:
| 248   3      28      | 58    12     7    | 145     6      9    |
| 5     679    279     | g69   4      12   | 13      137    8    |
| 1     46789  789     | 3     58     f69  | 45      2      47   |
:----------------------+-------------------+---------------------:
| I34   5      6       | h49    1239   8   | 7       1349   j234 |
| 3478  1478   1378    | 4679  12369  12   | 123489  1349   5    |
| 9     2      1378    | 47    13     5    | 1348    134    6    |
'----------------------'-------------------'---------------------'


I think I've got the notation right. The idea is to show that r1c7 must be a 4, because deleting a 4 also deletes all the 3's on row 1. I've underlined where the 3's are deleted:
-4r1c7 = (379)r1c127 - (379)r1c356 = (5)r1c3 - (5=6)r1c5 - (6)r1c6 = (6-9)r6c6 = (9)r5c4 -(9=4)r7c4 -(4=3)r7c1 -(3)r1c1|r7c9 = (3)r23c9 - (3)r1c7 => r1c7 = 4.
stte

[SteveG48]

"Leren
(4=9) r7c4 - r5c4 = (9-6) r6c6 = (6-4) r6c2 = (4) r8c2 => - 4 r7c1, r8c4; lclste

Leren

It took me a few days to figure out stte. This time I'll just ask: lclste?

[ArkieTech]

It took me a few days to figure out stte. This time I'll just ask: lclste?

Locked Cells Locked Sets To End

[daj95376]

It took me a few days to figure out stte. This time I'll just ask: lclste?

Some people feel the need to qualify the degree of difficulty in the remaining "basic" steps of the solution. I've never seen an "official" ordering on these steps, so I treat everything that ends in "...le" as extraneous.

FYI: The semi-Official (and unordered) Basic Steps

Code: Select all

*) Naked/Hidden Single

*) Locked Candidate (types) 1 & 2

*) Naked/Hidden Pair/Triple/Quad Subsets


Note: some people would like to include the X-Wing in the above list, but it's never been generally accepted.


I find "Locked Cells Locked Sets To End" to be a long-winded way of saying "Basics to End". Even "lclste" is the same number of letters as "Basics".

[Marty R.]

I find "Locked Cells Locked Sets To End" to be a long-winded way of saying "Basics to End".

I agree. But it's apparently important to some--correct me if I'm wrong--who seems to believe that a solution followed by "stte" is superior to a solution followed by "lcstte."

To me, basics are basics and I pay no attention to the letters after the solution, but it does no harm and those to whom it's important get to see what they want.

[SteveG48]

It took me a few days to figure out stte. This time I'll just ask: lclste?

Locked Cells Locked Sets To End

Thanks, all.

[DonM]

It took me a few days to figure out stte. This time I'll just ask: lclste?

Locked Cells Locked Sets To End

Thanks, all.

For a number of years, the standard ending for solutions was 'stte' or just 'ste' (singles to the end). I am not sure when and where 'lclste' was added, but there is a vagueness about it that doesn't fit with the objective of giving specific solution information. It's sort of like 'after my last notated chain', there may be a few line-box locked cells, a naked triple (or even a quad) and maybe a hidden pair or two- you figure out.' In other words, if 'lclste' means basic methods, then there can be any number of them, not to mention that there may be confusion on the part of the solver as to what constitutes 'basic methods'.

If one is comparing two solutions and they are equal in all other respects (ie. for instance, both consist of one basic chain), the one with 'stte' will ordinarily be the more efficient ie. better solution than the one with 'lclste'. In the case of 'stte' the puzzle falls apart with cascading singles. In the case of 'lclste', it doesn't.

IMO, a true single-stepper is a single chain that ends in 'stte'. One that ends in 'lclste' means that there are more than one step. It just makes sense.

[Marty R.]

IMO, a true single-stepper is a single chain that ends in 'stte'. One that ends in 'lclste' means that there are more than one step. It just makes sense.

I'm trying to learn here, not argue. If it ends with "lclste" there's more than one step. So what is that step? The way I've learned is that a "step" means an advanced move, i.e., a move other than subsets and Locked Candidates. Such as two-stepper, three-stepper and the like. So what would that extra step be called when there's an "lclste" at the end?

What would we lose if everyone stopped putting "stte" and "lclste" after their solutions?

[DonM]

IMO, a true single-stepper is a single chain that ends in 'stte'. One that ends in 'lclste' means that there are more than one step. It just makes sense.

I'm trying to learn here, not argue. If it ends with "lclste" there's more than one step. So what is that step? The way I've learned is that a "step" means an advanced move, i.e., a move other than subsets and Locked Candidates. Such as two-stepper, three-stepper and the like. So what would that extra step be called when there's an "lclste" at the end?

What would we lose if everyone stopped putting "stte" and "lclste" after their solutions?

I understand what you're saying (I think) ie. 'In the end, just what is a step?'. Back in the good old days when we just used 'stte', occasionally, usually due to human error, a solver would declare 'stte', but there was actually one or more locked cells/locked set steps intruding before the 'stte'. That would be pointed out to the solver by the others because it reflected a less efficient solution than was being implied.

I have a problem with the concept that seems to be implied in some posts above (and previously in the past) that basic steps that may follow after a main chain or main move are inconsequential. What if one of those steps is a naked quad? Is that a minor step? Is that a step that any manual solver would pick up quickly? Even triples can be hard for a manual solver to pick up in some puzzles. Besides, basic steps, after all, are called steps.

Repeating myself: In my book if a solver provides a main move that then falls apart with singles, that is simply better than another main move, similar in complexity, that doesn't fall apart until various locked cells/locked sets are solved. And if just one or two of those basic moves are left, then that solution is better than if 3 or 4 basic moves are left and so on.

[Leren]

Steve G48 wrote : -4r1c7 = (379)r1c127 - (379)r1c356 = (5)r1c3 - (5=6)r1c5 - (6)r1c6 = (6-9)r6c6 = (9)r5c4 -(9=4)r7c4 -(4=3)r7c1 -(3)r1c1|r7c9 = (3)r23c9 - (3)r1c7 => r1c7 = 4.

The only elimination I can see here is r1c7 <> 3

Leren