The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |.43|..6|...|
 |...|8.7|.3.|
 |98.|5..|.2.|
 |---+---+---|
 |...|...|..3|
 |.9.|312|.8.|
 |1..|...|...|
 |---+---+---|
 |.2.|..3|.17|
 |.1.|2.5|...|
 |...|1..|54.|
 *-----------*


Play/Print this puzzle online

[SteveG48]

Code: Select all

 *--------------------------------------------------------------------*
 |a7-5    4      3      | 9      2      6      | 8     g57     1      |
 | 2      56     1      | 8      4      7      | 69     3     f569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 *----------------------+----------------------+----------------------|
 | 45678  567    2      | 67     589    489    | 1      5679   3      |
 |b4567   9     d4567   | 3      1      2      | 47     8     e456    |
 | 1      3      45678  | 67     589    489    | 2      5679   4569   |
 *----------------------+----------------------+----------------------|
 |b568    2     c5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


(5)r1c1 - r57c1 = r7c3 - r5c3 = r5c9 - r2c9 = r1c8 => -5 r1c1

[pjb]

Code: Select all

 57     4      3      | 9      2      6      | 8      57     1     
 2     *56     1      | 8      4      7      | 69     3     *569   
 9      8      67     | 5      3      1      | 47     2      46     
 ---------------------+----------------------+---------------------
 45678  67-5   2      | 67     589    489    | 1      5679   3     
*4567   9     *4567   | 3      1      2      | 47     8     *456   
 1      3      45678  | 67     589    489    | 2      5679   4569   
 ---------------------+----------------------+---------------------
 568    2      5689   | 4      689    3      | 69     1      7     
 467    1      4679   | 2      679    5      | 3      69     8     
 3      67     6789   | 1      6789   89     | 5      4      2     


Sashimi X-Wing of 5s at r2c29, r5c139 => -5 r4c2; stte

Phil

[SteveG48]

Code: Select all

 *--------------------------------------------------------------------*
 | 57     4      3      | 9      2      6      | 8      57     1      |
 | 2     a56     1      | 8      4      7      | 69     3      69-5   |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 *----------------------+----------------------+----------------------|
 | 45678 b567    2      | 67     589    489    | 1      5679   3      |
 |c4567   9     c4567   | 3      1      2      | 47     8     d456    |
 | 1      3      45678  | 67     589    489    | 2      5679   4569   |
 *----------------------+----------------------+----------------------|
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


(5)r2c2 = r4c2 - r5c13 = r5c9 => -5 r2c9 ; stte

[SteveG48]

Hmm. When you look at the grids, my second solution is remarkably like Phil's, but you wouldn't guess it from the two descriptions!

[tlanglet]

Code: Select all

 *--------------------------------------------------------------------*
 | 57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 |----------------------+----------------------+----------------------|
 | 45678  567    2      | 67    *589    489    | 1     *5679   3      |
 | 4567   9      4567   | 3      1      2      | 47     8      456    |
 | 1      3      45678  | 67    *589    489    | 2     *5679   4569   |
 |----------------------+----------------------+----------------------|
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


In the past, I believe this pattern was called a Kraken x-wing(5); it is an "almost" x-wing. However viewing it as a Kraken column will hopefully prevent any terminology issues.

5r1c8-r1c1=5r2c2 => r4c2<>5
||
5r4c8 => r4c2<>5
||
5r6c8-r6c5=5r4c5 => r4c2<>5

[ArkieTech]

Code: Select all

 *--------------------------------------------------------------------*
 |*57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 |----------------------+----------------------+----------------------|
 | 45678  567    2      | 67     589    489    | 1      679-5  3      |
 |*4567   9     *4567   | 3      1      2      | 47     8     f456    |
 | 1      3      45678  | 67     589    489    | 2      679-5  4569   |
 |----------------------+----------------------+----------------------|
 |*568    2     *5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*
Finned Swordfish 5r157c138,fr5c9 => -5r46c8

[Marty R.]

Identical Sashimi to Phil's.

[Marty R.]

Code: Select all

 *--------------------------------------------------------------------*
 | 57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 |----------------------+----------------------+----------------------|
 | 45678  567    2      | 67    *589    489    | 1     *5679   3      |
 | 4567   9      4567   | 3      1      2      | 47     8      456    |
 | 1      3      45678  | 67    *589    489    | 2     *5679   4569   |
 |----------------------+----------------------+----------------------|
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


In the past, I believe this pattern was called a Kraken x-wing(5); it is an "almost" x-wing. However viewing it as a Kraken column will hopefully prevent any terminology issues.

5r1c8-r1c1=5r2c2 => r4c2<>5
||
5r4c8 => r4c2<>5
||
5r6c8-r6c5=5r4c5 => r4c2<>5

Ted, this is also what I learned as a "Fin Transport", whereby any number that would be eliminated by the X-Wing and sees the cell to which the fin was transported can be eliminated. The fin (r1c8) is transported to r2c2 which meets the conditions for a Fin Transport which eliminates the 5 from r4c2.

[DonM]

Code: Select all

 *--------------------------------------------------------------------*
 | 57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 |----------------------+----------------------+----------------------|
 | 45678  567    2      | 67    *589    489    | 1     *5679   3      |
 | 4567   9      4567   | 3      1      2      | 47     8      456    |
 | 1      3      45678  | 67    *589    489    | 2     *5679   4569   |
 |----------------------+----------------------+----------------------|
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


In the past, I believe this pattern was called a Kraken x-wing(5); it is an "almost" x-wing. However viewing it as a Kraken column will hopefully prevent any terminology issues.

5r1c8-r1c1=5r2c2 => r4c2<>5
||
5r4c8 => r4c2<>5
||
5r6c8-r6c5=5r4c5 => r4c2<>5

Yes, it has been called a Kraken x-wing which is unfortunate because it really is a simple pattern, yet Kraken was also used for various AAIC nets. For newer solvers who are not familiar with it:

Ordinarily, the (5)r1c8 fin of the x-wing would not allow the exclusion of (5)r4c2, but because the fin (5)r1c8 'sees' (5)r4c2 through the conjugate pair (5)r2c9->(5)r2c2, you have this situation: If the fin is true, (5)r4c2 will be eliminated, but if the fin is not true, then the x-wing is true and (5)r4c2 will still be eliminated.

Great find Ted- these are not that easy to pick up and they aren't all that common (though not as uncommon as one might think).

IMO, this is a 'what-is' pattern: All you have to do is declare the x-wing, the fin and the conjugate pair and the given exclusion is thus supported.

[tlanglet]

Code: Select all

 *--------------------------------------------------------------------*
 | 57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 |----------------------+----------------------+----------------------|
 | 45678  567    2      | 67    *589    489    | 1     *5679   3      |
 | 4567   9      4567   | 3      1      2      | 47     8      456    |
 | 1      3      45678  | 67    *589    489    | 2     *5679   4569   |
 |----------------------+----------------------+----------------------|
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *--------------------------------------------------------------------*


In the past, I believe this pattern was called a Kraken x-wing(5); it is an "almost" x-wing. However viewing it as a Kraken column will hopefully prevent any terminology issues.

5r1c8-r1c1=5r2c2 => r4c2<>5
||
5r4c8 => r4c2<>5
||
5r6c8-r6c5=5r4c5 => r4c2<>5

Yes, it has been called a Kraken x-wing which is unfortunate because it really is a simple pattern, yet Kraken was also used for various AAIC nets. For newer solvers who are not familiar with it:

Ordinarily, the (5)r1c8 fin of the x-wing would not allow the exclusion of (5)r4c2, but because the fin (5)r1c8 'sees' (5)r4c2 through the conjugate pair (5)r2c9->(5)r2c2, you have this situation: If the fin is true, (5)r4c2 will be eliminated, but if the fin is not true, then the x-wing is true and (5)r4c2 will still be eliminated.

Great find Ted- these are not that easy to pick up and they aren't all that common (though not as uncommon as one might think).

IMO, this is a 'what-is' pattern: All you have to do is declare the x-wing, the fin and the conjugate pair and the given exclusion is thus supported.

Don,

Thanks for the background info. I have always felt that the use of the term "Kraken" was funny and not appropriate. Today, I am of the opinion that the term "almost" is applicable to all patterns, AICs, etc. when one (or more) extra digit is involved.

Ted

[daj95376]

There have been various descriptions over the years for a Fish with a fin cell that doesn't directly see an elimination.

I proposed direct and indirect classifications -- depending upon whether or not a fin cell did or didn't directly see an elimination, respectively.
(All of the logic was restricted to the candidates for the fish value.)

RonK proposed: (All of the logic was restricted to the candidates for the fish value.)

Code: Select all

endo-  fin cell:  A cell inside  the intersection of two or more  Base  sectors
exo-   fin cell:  A cell outside the intersection of the Base and Cover sectors
remote fin cell:  A cell that only sees an elimination cell indirectly through the fish pattern


I was never comfortable with "indirectly through the fish pattern" -- as exemplified by Ted's use of r1c1 and r2c2. However, others adopted the remote classification for any indirect fin cell -- so I now use remote for consistency.

If you reference TUFG ...

Shape of Fish:

1. Basic: N row sectors x N column sectors or vv.
2. Franken: N (rows+Nonet) sectors x N (columns+Nonet) sectors or vv.
3. Mutant: N sectors x N sectors (That is not Basic nor Franken)
4. Kraken: Any fish (1-3) that requires life support (information from outside the pattern)

IIRC, RonK talked Mike Barker into starting his own thread for Kraken Fish when Mike used values other than the fish value to link an indirect fin cell to an elimination cell.

Bottom Line IMO: most people are going to use whatever description they remember.

[eleven]

Sashimi X-Wing

Kraken x-wing

Finned Swordfish

Much noise on a (grouped) skyscraper puzzle

[David P Bird]

Code: Select all

 *----------------------*----------------------*----------------------*
 | 57     4      3      | 9      2      6      | 8     *57     1      |
 | 2      56     1      | 8      4      7      | 69     3      569    |
 | 9      8      67     | 5      3      1      | 47     2      46     |
 *----------------------*----------------------*----------------------*
 | 45678  567    2      | 67    *589    489    | 1     *5679   3      |
 | 4567   9      4567   | 3      1      2      | 47     8      456    |
 | 1      3      45678  | 67    *589    489    | 2     *5679   4569   |
 *----------------------*----------------------*----------------------*
 | 568    2      5689   | 4      689    3      | 69     1      7      |
 | 467    1      4679   | 2      679    5      | 3      69     8      |
 | 3      67     6789   | 1      6789   89     | 5      4      2      |
 *----------------------*----------------------*----------------------*

Using the XWIng as a Boolean node in an AIC we get a simple un-branched chain:

(5)r4c2 - (5#2)Xwing:c58\r46 = (5)Fin:r1c8 - (5)r1c1 = (5)r2c2 - (5)r4c2 => r4c2 <> 5

In other non-fish discussions a Kraken node is considered to be a hub for 3 chain segments as an excuse to allow unconfined branching. In that light I find it inconsistent to use the term to describe what to me is a perfectly ordinary elimination from an AIC with an embedded fish pattern.

The hub in question is the Potential Elimination cell r4c2. It would be a conventional Kraken node if it connected to say another fin cell at r8c8 through a second chain. (The rule being that any PE cell that would make all fin cells false must be false.)

This anomaly for the Kraken Fish term goes back a long way though.

[pjb]

Whether or not one likes the term 'kraken x-wing', interestingly there is a second one there (with same outcome as Steve's first solution):

Code: Select all

 7-5    4      3      | 9      2      6      | 8     c57     1     
 2      56     1      | 8      4      7      | 69     3     b569   
 9      8      67     | 5      3      1      | 47     2      46     
 ---------------------+----------------------+---------------------
 45678  567    2      | 67     589    489    | 1      5679   3     
*4567   9     *4567   | 3      1      2      | 47     8     a456   
 1      3      45678  | 67     589    489    | 2      5679   4569   
 ---------------------+----------------------+---------------------
*568    2     *5689   | 4      689    3      | 69     1      7     
 467    1      4679   | 2      679    5      | 3      69     8     
 3      67     6789   | 1      6789   89     | 5      4      2     


x-wing r57c13, fin r5c9, transport viar2c9 abd r1c8 => -5 r1c1
Phil