The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.8.|.6.|5..|
 |635|..9|...|
 |4..|..7|.1.|
 |---+---+---|
 |.5.|...|...|
 |2..|6.8|..5|
 |...|...|.3.|
 |---+---+---|
 |.9.|8..|..6|
 |...|7..|451|
 |..7|.2.|.9.|
 *-----------*


Play/Print this puzzle online

[Leren]

Code: Select all

*--------------------------------------------------------------*
| 7     8     1      | 3     6     24     | 5     24    9      |
| 6     3     5      | 124  a14    9      | 27    8    b47     |
| 4     2     9      | 5     8     7      | 6     1     3      |
|--------------------+--------------------+--------------------|
| 39    5     8      | 249  d347   24     | 1     6    c247    |
| 2     147   34     | 6    e347-1 8      | 9     47    5      |
| 19    147   6      | 1249  1457  15     | 8     3     247    |
|--------------------+--------------------+--------------------|
| 13    9     34     | 8     145   15     | 27    27    6      |
| 8     6     2      | 7     9     3      | 4     5     1      |
| 5     14    7      | 14    2     6      | 3     9     8      |
*--------------------------------------------------------------*

(1=4) r2c5 - (4=7) r2c9 - (7) r4c9 = (7-3) r4c5 = (3) r5c5 = > - 1 r5c5; stte

Leren

PS Shortened chain as per Phil's advice.

Leren

[pjb]

Code: Select all

 7       8       1      | 3      6      24     | 5      24     9     
 6       3       5      | 124    1-4    9      | 27     8     a47     
 4       2       9      | 5      8      7      | 6      1      3     
------------------------+----------------------+---------------------
d39      5       8      | 249   c347    24     | 1      6     b247   
 2       147    e34     | 6      1347   8      | 9      47     5     
 19      147     6      | 1249   1457   15     | 8      3      247   
------------------------+----------------------+---------------------
 13      9      f34     | 8     g145    15     | 27     27     6     
 8       6       2      | 7      9      3      | 4      5      1     
 5       14      7      | 14     2      6      | 3      9      8     


(4=7)r2c9 - r4c9 = (7-3)r4c5 = r4c1 - (3=4)r5c3 - r7c3 = r7c5 => -4 r2c5; stte

Phil

PS Leren: You could omit 2nd and 3rd terms to make your chain even shorter

[omerosler]

Code: Select all

*--------------------------------------------------------------*
| 7     8     1      | 3     6    b24     | 5    c24    9      |
| 6     3     5      | 124  a14    9      | 27    8    d47     |
| 4     2     9      | 5     8     7      | 6     1     3      |
|--------------------+--------------------+--------------------|
| 39    5     8      | 249  f347   24     | 1     6    e247    |
| 2     147   34     | 6    g347-1 8      | 9     47    5      |
| 19    147   6      | 1249  1457  15     | 8     3     247    |
|--------------------+--------------------+--------------------|
| 13    9     34     | 8     145   15     | 27    27    6      |
| 8     6     2      | 7     9     3      | 4     5     1      |
| 5     14    7      | 14    2     6      | 3     9     8      |
*--------------------------------------------------------------*

(1=4) r2c5 - (4=2) r1c6 - (2=4) r1c8 - (4=7) r2c9 - (7) r4c9 = (7-3) r4c5 = (3) r5c5 = > - 1 r5c5; stte

Leren

Why go through all this trouble?
You have an X-Wing on 1 R67C16;
A double sashimi X-Wing (is it called a 2-skyscrapper?) on 4 in R1C68 R4C6 R5C8;
A locked triple of {249} in middle block R4C46 R6C4;
Double sashimi-Swordfish (is it called a 3-skyscrapper?) on 4: R1C8 R2C5 R5C38 R8C35;
stte

[SteveG48]

Code: Select all

 *-----------------------------------------------------------*
 | 7     8     1     | 3     6     24    | 5     24    9     |
 | 6     3     5     | 124   1-4   9     | 27    8    d47    |
 | 4     2     9     | 5     8     7     | 6     1     3     |
 *-------------------+-------------------+-------------------|
 | 39    5     8     | 249  b347   24    | 1     6    c247   |
 | 2     147   34    | 6     1347  8     | 9     47    5     |
 | 19    147   6     | 1249 a1457 a15    | 8     3     247   |
 *-------------------+-------------------+-------------------|
 | 13    9     34    | 8    a145  a15    | 27    27    6     |
 | 8     6     2     | 7     9     3     | 4     5     1     |
 | 5     14    7     | 14    2     6     | 3     9     8     |
 *-----------------------------------------------------------*


(4=7)r67c56[1/5 UR] - r4c5 = r4c9 - (7=4)r2c9 => -4 r2c5 ; stte

[bat999]

Code: Select all

.----------------.--------------------.--------------.
|  7     8    1  |  3       6      24 | 5   24   9   |
|  6     3    5  |  124    b14     9  | 27  8   b47  |
|  4     2    9  |  5       8      7  | 6   1    3   |
:----------------+--------------------+--------------:
|  3-9   5    8  | a249     347   a24 | 1   6   a247 |
|  2    d147  34 |  6      c1347   8  | 9   47   5   |
| e19    147  6  |  124-9   1457   15 | 8   3    247 |
:----------------+--------------------+--------------:
|  13    9    34 |  8       145    15 | 27  27   6   |
|  8     6    2  |  7       9      3  | 4   5    1   |
|  5     14   7  |  14      2      6  | 3   9    8   |
'----------------'--------------------'--------------'

(9=7)r4c469 - (7=1)r2c59 - r5c5 = r5c2 - (1=9)r6c1 => -9 r4c1,r6c4; stte

[Leren]

omerosler wrote : Why go through all this trouble?

The reason we "go through all this trouble" with these daily puzzles is that we solve them with a restricted set of "rules" that make the puzzle a bit harder to solve.

The idea is to use basic moves, followed by one non-basic move that solves the puzzle except for follow-on singles or basics.

"Basic moves" in this context includes singles, pointing and claiming pairs and triples, naked and hidden pairs, triples and quads.

One of the peculiarities of this system is that basic fish (XWings, SwordFish and Jellyfish) are effectively excluded from consideration, although finned fish, franken fish and mutant fish are acceptable non-basic moves.

Irrespective of whether anyone who is not familiar with this system thinks it is reasonable or not, the fact is that it has proven to be very popular over recent years and is the most active part of this forum.

As Phil pointed out my non-basic move was a bit longer than necessary, so I've shortened it to (1=4) r2c5 - (4=7) r2c9 - (7) r4c9 = (7-3) r4c5 = (3) r5c5 = > - 1 r5c5.

Leren

[omerosler]

Okay, didn't know about that and it sounds like a nice challenge.
Maybe I'll give it a go tomorrow

[Leren]

Okay, didn't know about that and it sounds like a nice challenge.
Maybe I'll give it a go tomorrow

If you do decide to participate, there is one more thing you need to know.

There are two acceptable endings following the non-basic move:

1. stte (which stands for singles to the end) if only follow-on singles are required to complete the puzzle.

2. lclste (which stands for something like locked candidates, locked sets to the end) if at least one non-single basic move is required to complete the puzzle.

You should also be aware of two facts :

Fact 1 : stte endings and lclste endings are considered to be of equal merit.

Fact 2: Nobody really believes Fact 1 !

stte is the Sudoku tragic's equivalent of standing on the bow of the Titanic screaming "I'm king of the world", or somesuch.

lclste is the equivalent of being lucky enough to get on a lifeboat when the Titanic sinks.

Hopefully you can see I'm not being serious here. Anyway, welcome to Dan's daily puzzles and happy hunting !

Leren

[Sudtyro2]

One of the peculiarities of this system is that basic fish (XWings, SwordFish and Jellyfish) are effectively excluded from consideration, although finned fish, franken fish and mutant fish are acceptable non-basic moves.

Hi Leren,
I've missed something completely (rarely happens) . Could you elaborate at bit on the above Fish statement? I didn't realize that basic fish were not acceptable as non-basic moves. That would seem to say that a commonly used elimination, say, from a discontinuous X-Chain loop (AIC) is non-basic. But, elimination(s) from a continuous X-Chain loop, a "Fishy Cycle" (and actually a basic fish) is not acceptable. Help?

SteveC

[Leren]

Hi Steve, I don't know the history of how this came about but it's True - basic fish are effectively eliminated from Dan's daily puzzles. I recall that one of the first times I posted a solution I used a basic fish before the non-basic move, and someone asked me why my PM was different than anyone else's. I quickly got the message.

One reason might be that the daily puzzles are supposed to be just out of reach of newspaper standard puzzles, and since basic fish are commonly used in newspaper standard puzzles they are out.

Recently one of the dailies solved with an XY Wing, which is also commonly used in newspaper puzzles and I considered asking Dan to submit a replacement on the basis that it was too easy. I didn't say anything because others had posted more complex moves ! Similarly, if a puzzle solved with a 2 Strong link move it would be considered to be too easy. That would rule out Skyscrapers, Empty Rectangles and Kites as the non-basic move.

Leren

[SteveG48]

Leren, I don't think Steve was asking why basic fish aren't allowed as basic moves. He was asking why they would be excluded as non-basic one-step solutions to the puzzle after the basic moves are completed. I think they would be allowed- but in the time I've been here I don't think Dan has ever posted a puzzle that could be reduced to singles by a basic fish.

Of course, some folks here consider a finned frankin squirmbag to be a basic fish.

[Sudtyro2]

Leren, I don't think Steve was asking why basic fish aren't allowed as basic moves. He was asking why they would be excluded as non-basic one-step solutions to the puzzle after the basic moves are completed. I think they would be allowed ...

Thx Steve, that is correct. Let me try to clarify...

1. I consider the "basic moves" to be only what Leren listed: singles, pointing and claiming pairs and triples, naked and hidden pairs, triples and quads.
I think those are also equivalent to the first six steps in Andrew Stuart's online solver.

2. Everything else I thought would be non-basic moves, including basic fish and 2-Strong-link moves.

3. But then Leren also states: "That would rule out Skyscrapers, Empty Rectangles and Kites as the non-basic move."

Sorry, but I'm still confused.

SteveC

[Marty R.]

Code: Select all

+-----------+--------------+-----------+
| 7  8   1  | 3    6    24 | 5  24 9   |
| 6  3   5  | 124  14   9  | 27 8  47  |
| 4  2   9  | 5    8    7  | 6  1  3   |
+-----------+--------------+-----------+
| 39 5   8  | 249  347  24 | 1  6  247 |
| 2  147 34 | 6    1347 8  | 9  47 5   |
| 19 147 6  | 1249 1457 15 | 8  3  247 |
+-----------+--------------+-----------+
| 13 9   34 | 8    145  15 | 27 27 6   |
| 8  6   2  | 7    9    3  | 4  5  1   |
| 5  14  7  | 14   2    6  | 3  9  8   |
+-----------+--------------+-----------+


Play this puzzle online at the Daily Sudoku site

(1=5)r7c6-(5=1)r6c6-r6c1=r7c1=> -1r7c6

Leren, is this a valid AIC Type 2?

[Ngisa]

Code: Select all

+-----------+--------------+-----------+
| 7  8   1  | 3    6    24 | 5  24 9   |
| 6  3   5  | 24-1  h14   9  | 27 8  g47  |
| 4  2   9  | 5    8    7  | 6  1  3   |
+-----------+--------------+-----------+
| d39 5   8  | 249  e347  24 | 1  6  f247 |
| 2  147 34 | 6    1347 8  | 9  47 5   |
| 19 147 6  | 1249 1457 15 | 8  3  247 |
+-----------+--------------+-----------+
| c13 9   34 | 8    145  15 | 27 27 6   |
| 8  6   2  | 7    9    3  | 4  5  1   |
| 5  b14  7  | a14   2    6  | 3  9  8   |
+-----------+--------------+-----------+


(1)r9c4 = r9c2 - (1=3)r7c1 - r4c1 = (3-7)r4c5 = r4c9 - (7=4)r2c9 - (4=1)r2c5 => -1r2c4; stte

Clement