The New Sudoku Players' Forum

[SpAce]

I'm sure all of you remember the Pure Swordfish Collection http://forum.enjoysudoku.com/a-pure-swordfish-collection-t5775.html

Nice! One thing caught my eye in the rules:

Code: Select all

7. NEEDS a Swordfish to solve after applying the following set of techniques:
   ...
   7.11. BUG+1

Now that would be an interesting puzzle!

PS. Is there a current list of such collections for other techniques anywhere? There's this, but it's obviously not very comprehensive or up-to-date. It would be awesome to have a single point of reference to find lots of good examples of any pattern. It would help both manual solvers and software builders.

[denis_berthier]

I'm sure all of you remember the Pure Swordfish Collection http://forum.enjoysudoku.com/a-pure-swordfish-collection-t5775.html

Yes, sure, I remember. A reference for all of us. But I don't remember seeing in it puzzles with so many Subsets.

[mith]

Added an improved version, at least by the swordfish count.

[SpAce]

Code: Select all

        \7      \23567    \2367                            \5       \2356
.------------------------.------------------------.--------------------------.
| 56789  2389-7  8-23567 | 1489-367  13489  14679 | 14579   2489-5   1489-25 |
| 1      89*7    8*567   | 489*67    489    2     | 3       489*5    489*5   | *567
| 789    4       8^23-7  | 189^3-7   5      179   | 179     6        189^2   | ^23
:------------------------+------------------------+--------------------------:
| 4589   6       48^3-5  | 489^2     7      459   | 459     1        ^23     | ^23
| 2      19*7    14*57   | 149*6     149    3     | 8       49*5     49*56   | *567
| 4589   1389    148-35  | 1489-26   12489  14569 | 4569    23       7       |
:------------------------+------------------------+--------------------------:
| 4678   128-7   9       | 5         23     147   | 146     348      1468-3  |
| 48     5       148^2   | ^23       6      149   | 149     7        1489^3  | ^23
| 3      1*7     14*67   | 149*7     149    8     | 2       49*5     149*56  | *567
'------------------------'------------------------'--------------------------'

Step 1. Five Lightsaberfishes:

15x15 {23r348 567r259 \ 236c349 5c389 7c234} => 22 elims

individuals: Show

(2)r348\c349 => -2r1c39,r6c4
(3)r348\c349 => -3r16c3,r1c4,r7c9
(5)r259\c389 => -5r146c3,r1c89
(6)r259\c349 => -6r1c3,r16c4,r7c9
(7)r259\c234 => -7r17c2,r13c34

Or:

(2)c258\r167
(3)c258\r167
(5)c167\r146
(6)c167\r167
(7)c167\r137

Code: Select all

  \8                 \48      \4                     \4     \48
.------------------.-------------------------.----------------------.
|  56     23   8   | ^149     ^1349    67    | 57    ^249   ^149    | ^4
|  1      79   56  | ^4679-8  ^489     2     | 3     ^4589  ^459-8  | ^4
|  79     4    23  | *38       5       179   | 179    6     *28     | *8
:------------------+-------------------------+----------------------:
| *4589   6    34  | *289-4    7       459   | 459    1      23     | *8
|  2      179  57  | ^1469    ^149     3     | 8     ^459   ^4569   | ^4
|  459-8  38   14  |  19-48    1289-4  14569 | 4569   23     7      |
:------------------+-------------------------+----------------------:
|  467-8  28   9   |  5        23      147   | 146    38-4   1-48   |
| *48     5    124 |  23       6       149   | 149    7     *1389-4 | *8
|  3      17   67  | ^1479    ^149     8     | 2     ^459   ^14569  | ^4
'------------------'-------------------------'----------------------'

Step 2. Jedi(scum)fish + Lightsaberfish:

7x7 {4r1259 8r348 \ 4c4589 8c149} => 12 elims; stte

(The Jedi without her lightsaber yields btte.)

individuals: Show

(4)r1259\c4589 => -4 r46c4,r6c5,r7c89,r8c9; btte (alone)
(8)r348\c149 => -8 r67c1,r26c4,r27c9; stte (both)

Or:

(4)c1367\r4678
(8)c258\r267

[mith]

Nice. Yeah, with the jellyfish only five swordfish + basics are needed (at least, I haven't found a way to do it with four). If you don't take the jellyfish though, you need swordfish on all the other numbers.

[SpAce]

Nice.

Thanks! I've never been much of a fisherman, but these have been super easy to spot. I think it helps tremendously to know that there are fishes to be found. In normal puzzles I rarely bother to look for them, unless the puzzle has very weak chaining potential. Thus I'm very likely to miss even basic Swordfishes, unless they're also X-Chains. That's why fish-focused exercises like these are very welcome.

Yeah, with the jellyfish only five swordfish + basics are needed (at least, I haven't found a way to do it with four). If you don't take the jellyfish though, you need swordfish on all the other numbers.

Indeed. I took the pure Swordfish route first. Very nice design! I only noticed the 4-Jellyfish on my second round when writing up the solution, and somewhat surprisingly it gave a bit shorter path, so I took it.

[mith]

https://www.youtube.com/watch?v=V38qsL1cmFs&t=60s

[SpAce]

https://www.youtube.com/watch?v=V38qsL1cmFs&t=60s

Congratulations! It was a nice puzzle.

I'm just surprised the cryptic guy thought it was really hard. (I only watched the beginning so I don't know how he actually solved it. I can't think of anything more boring than watching sudoku videos )

[mith]

He didn't actually solve it on the video. My assumption is that he found the initial swordfish and the resulting pairs/triples, but didn't spot one of the subsequent fish. It's a lot to keep track of without full candidate markings (for the videos, they tend to only mark candidates locked in two places in a box, or cells restricted to two or three candidates; ordinarily for a fish they would color the cells to keep track of it, but that's not practical here.)

I'll have to send him another for redemption.

[Pupp]

https://www.youtube.com/watch?v=12lPDRFXhYs&t=535s

I also started a new thread about this, since this is new technique and I wanted it to get more noticed than a thread that is a "puzzle" thread. It just happens that Cracking the Cryptic used this particular puzzle in his video.

[mith]

You might want to read the first reply in this thread

[mith]

Tatooine Sunset is going to appear in CTC's book (that they are doing through kickstarter), hopefully along with a brand new puzzle from me (I've been working on that this week, thus the lack of new forum posts). Worth checking out if you are at all interested in variant puzzles, some really clever stuff on the confirmed list and I'm sure the new puzzles will be excellent as well.