The New Sudoku Players' Forum

[ronk]

This MAY cause confusion when naming & referring to fish.......

I propose to back from my initial position of limiting it to finned basic fish & leave it as a sub-category of Finned fish........

(...)

examples of complete long names of fish names:
Finless basic x-wing (your normal everyday x-wing)
Sashimi Finned basic swordfish
Simple finned mutant jellyfish

The terms above all of a sudden make things a bit clearer, I hope everybody agrees to this so that we could get rid of this curse.

I don't agree, probably because I don't see the problem.

1) A finned fish doesn't degenerate when all the fin cells are false.
2) A sashimi fish does degenerate when all the fin cells are false.

It should be obvious from statement 2 that sashimi fish are finned, so saying "sashimi finned" is redundant.

Might a sashimi fish have even more fins than those required to prevent degeneration? Sure, but that shouldn't matter. We don't make a distinction as to whether a finned fish has 1, 2 or 3 fins either.

[tarek]

What you are describing is the situation as per our last agreement. However we only agreed to use the sashimi term for BASIC fish to ease the transition from basic to franken fish......

In the Naming of fish section of the head post, I've put sashimi as a sub category eqivalent to Finned Basic fish & sashimi does not appear anywhere else........

My problem is with the over use of sashimi (even if correct) outside that circle.

My propostion is to -once & for all- attempt to clear this & reach a universal agreement.

Anything that has "fins" should be described as "finned" whethter sashimi or not ---- this argument has merit & was opposed by me because "Sashimi was used at instances replacing the word Finned".

I still oppose the use of "sashimi" to replace "finned". Instead, I propose adding "sashimi" as an additional prefix to describe finned fish.

A finned fish therefore can be a sashimi finned fish or a Simple (or any other more appropriate term) finned fish (the use of the word simple just like finless can be optional & only enforced when using the full long name). "simple" describes the non degenerative pattern while "sashimi" describes the degenerative pattern.

I hope this clarifies matters........

I know that there is no problem at this time (how many people in the world use sashimi when fishing nowadays?) but with the increased use of the terms, I'm predicting problems with nomencalture & therefore all this debate......

tarek

[ronk]

What you are describing is the situation as per our last agreement. However we only agreed to use the sashimi term for BASIC fish to ease the transition from basic to franken fish......

We apparently concluded that the "finned" and "sashimi" adjectives could be dropped. I'll have to go back to review how that transpired.

However, in view of the above, it seems ironic that we're now considering switching from dropping one adjective to adding another. Maybe someone else will weigh in here.

[daj95376]

I should stay out of any discussion on fish, but I would like to comment here anyway. Consider the following example.

Code: Select all

# finned Kraken Swordfish r156\c167
# (8) [r6c5]-[r79c5]=[r79c4]-[r23c4]=[r3c6] => [r3c1]<>8
*-----------------------------------------------------------*
|*4689 #689  #489   | 1     3     7     |*489   5     2     |
| 2     1     3     | 489   5     6     | 7     49    489   |
| 49-8  5     7     | 489   2     48    | 6     1     3     |
|-------------------+-------------------+-------------------|
| 5     3     89    | 7     1     2     | 489   469   689   |
|*89    4     1     | 3     6    *89    | 2     7     5     |
| 7     2     6     | 5    @48   *489   |*89    3     1     |
|-------------------+-------------------+-------------------|
| 1     6789  2     | 468   478   5     | 3     469   4679  |
| 46    67    5     | 2     9     3     | 1     8     467   |
| 3     6789  489   | 468   478   1     | 5     2     4679  |
*-----------------------------------------------------------*


Cells [r1c23] and [r6c5] are outside the cover set. This makes them 'fin' cells to me. However, I view them completely differently. Without cell [r6c5], this PM is clearly a finned Swordfish. Without cells [r1c23], this PM represents a Kraken Swordfish. Now, what's the name of it with all three cells present? That's for you to decide!

Now, what would you call this PM if cell [r1c1] was not in the base set?

(Note: this PM was originally presented in this thread as a finned mutant Jellyfish by Ocean. The original puzzle was from Nick70.)

[ronk]

Consider the following example.
...
# finned Kraken Swordfish r156\c167
# (8) [r6c5]-[r79c5]=[r79c4]-[r23c4]=[r3c6] => [r3c1]<>8
...
Without cells [r1c23], this PM represents a Kraken Swordfish. Now, what's the name of it with all three cells present? That's for you to decide!

Now, what would you call this PM if cell [r1c1] was not in the base set?

For me, in all three cases, it's a swordfish with a remote fin. The remote fin is the overriding feature of the fish. Whether or not there are also non-remote fins and whether or not it's also sashimi seem secondary.

From the viewpoint of the exemplar catalog it's a non-issue. Remotely-finned fish are not being considered for the catalog, partly because the possibilities are endless. In such a case, one can always look for a slightly larger fish without a remote-fin. For example, for your exclusion r3c1<>8 ...

Code: Select all

 4689  689   489   |/1    /3    /7     |*489  /5    /2   
 2     1     3     |*489   5     6     | 7     49   *489 
 49-8  5     7     |*489   2    *48    | 6    /1    /3   
-------------------+-------------------+------------------
 5     3    *89    | 7     1     2     |*489   469  *689 
#89   /4    /1     | 3     6     89    | 2    /7    /5   
 7    /2    /6     | 5     48    489   |*89   /3    /1   
-------------------+-------------------+------------------
 1     6789  2     | 468   478   5     | 3     469   4679
 46    67    5     | 2     9     3     | 1     8     467 
 3     6789  489   | 468   478   1     | 5     2     4679

 (sashimi) mutant jellyfish b2346\r234c7 plus fin r5c1

In the traditional sense, the jellyfish is sashimi because of the naked single in b4 if r5c1<>8.

BTW since we use the term empty rectangle (ER) for the patterns in b3, b4 and b6, perhaps we should have a name for the pattern in b2 also -- like "empty line" (EL).

[Obi-Wahn]

That reminds me of a comment I wanted to give on this example weeks ago, but had to wait for the activation of my account.

The pattern supposed by Ocean was a Finned Mutant (Jellyfish) b1346/r14c17 with fin r2c9. Since I consider the sector connecting the fin with the elimination candidate (r1c7) as just an additional cover sector (in this case b3), this leads to a situation where the same sector is used for both the base and the cover set. In this case this sector can be deleted from both sets, leaving b146/r14c17 where each of the sectors that include the elimination candidate (r1 and c7) can be treated as additional cover sector.
So we have:

Code: Select all

*8 #8 #8 | .  .  . |-8  .  .
 .  .  . | 8  .  . | .  .  8
*8  .  . | 8  .  8 | .  .  .
---------+---------+---------
 .  . *8 | .  .  . |*8  . *8
*8  .  . | .  .  8 | .  .  .
 .  .  . | .  8  8 |*8  .  .
---------+---------+---------
 .  8  . | .  .  . | .  .  .
 .  .  . | 8  8  . | .  .  .
 .  8  8 | 8  8  . | .  .  .

Sashimi Mutant Swordfish b146/r4c17 with fin r1c23


*8 *8 *8 | .  .  . |-8  .  .
 .  .  . | 8  .  . | .  .  8
*8  .  . | 8  .  8 | .  .  .
---------+---------+---------
 .  . *8 | .  .  . |*8  . *8
*8  .  . | .  .  8 | .  .  .
 .  .  . | .  8  8 |#8  .  .
---------+---------+---------
 .  8  . | .  .  . | .  .  .
 .  .  . | 8  8  . | .  .  .
 .  8  8 | 8  8  . | .  .  .

Sashimi Mutant Swordfish b146/r14c1 with fin r6c7


In daj95376's example to eliminate r3c1 you can just replace c6 by b5 in the cover set to remove the remote fin:

Code: Select all

*8 #8 #8 | .  .  . |*8  .  .
 .  .  . | 8  .  . | .  .  8
-8  .  . | 8  .  8 | .  .  .
---------+---------+---------
 .  .  8 | .  .  . | 8  .  8
*8  .  . | .  . *8 | .  .  .
 .  .  . | . *8 *8 |*8  .  .
---------+---------+---------
 .  8  . | .  .  . | .  .  .
 .  .  . | 8  8  . | .  .  .
 .  8  8 | 8  8  . | .  .  .

Finned Franken Swordfish r156/c17b5 with fin r1c23


BTW, I totally agree with ronk that the combination of the adjectivs Sashimi and Finned would only make sense if there could be such a thing as a finless Sashimi fish, which isn't the case. So I don't even see future problems and certainly won't support unnecessarily extended names.
Besides, I can't remember having read that combination before.

From the viewpoint of the exemplar catalog it's a non-issue. Remotely-finned fish are not being considered for the catalog, partly because the possibilities are endless. In such a case, one can always look for a slightly larger fish without a remote-fin.

Of course you can look for it, but will you always find one? I have an example where daj95376 found an exo/remote finned Swordfish but no other fish without remote fins showed up yet.

[tarek]

Excellent catch Obi-Wahn.......

By the way, I also have no problem in keeping things as they are & ammend the the head post to make use of the term sashimi in all fish shapes.........

Now regarding Sashimi (again)......The term is kept to describe Fish where the fish would degenerate if a fin was removed......This means that one of the base sectors should harbour only the fin for that to happen.......I can't see that in your examples....

tarek

[Obi-Wahn]

Now regarding Sashimi (again)......The term is kept to describe Fish where the fish would degenerate if a fin was removed......This means that one of the base sectors should harbour only the fin for that to happen.......

Not necessarily. A sashimi jellyfish for example can degenrate into two x-wings without the fin. In this case all the base sectors still harbour two vertices without the fin.

In my first example removing the fin r1c23 leaves locked candidates (only one vertex) int r13c1 that lead to r5c1<>8 => r4c3=8 => r4c79<>8 => r6c7=8. That's what I would call degenerating.
In the second example removing the fin leaves locked candidates (one vertex) in r4c79 leading to r4c3<>8 => r5c1=8 => r13c1<>8.

I'm thinking about building a matrix for the resulting finless fish, where an asterisk marks vertices that actually contain at least one candidate. For my first example that would be:

Code: Select all

   | r4  c1  c7
---+------------
b1 |     *
b4 | *   *
b6 | *       *


In this matrix you can easily look for singles or smaller fish. If you find one, the fish degenerates without the fin.

There's another thing I'd like to point out. With Sashimi fish you often distinguish between real vertices (which contain a candidate) and virtual vertices (which don't) and discussed wether to mark them in the diagrams, because by adding candidates to the virtual vertices you could turn a sashimi fish into a finned one.
But in fact there is a third kind of vertex that just doesn't exist, because the according base and cover sectors don't overlap. You may call those non existent vertices imaginary vertices. b1/r4 would be an example. Of course that's only possible for Franken or Mutant fish.

[ronk]

I'm thinking about building a matrix for the resulting finless fish, where an asterisk marks vertices that actually contain at least one candidate. For my first example that would be:

Code: Select all

   | r4  c1  c7
---+------------
b1 |     *
b4 | *   *
b6 | *       *


In this matrix you can easily look for singles or smaller fish. If you find one, the fish degenerates without the fin.

The interesting thing about that r146\r4c17 swordfish is that b1 doesn't intersect with r4 or c7 ... so no finned (non-sashimi) version can ever exist. I'm sure there are many many others like that.

[tarek]

[Edited] Rethinking ..........

tarek

[Obi-Wahn]

@ronk: I just edited in my comment about imaginary vertices when you replied to my post.

@tarek: I think I'm well within your definition, because two x-wings are not of the same size as a jellyfish.

The interesting thing about that r146\r4c17 swordfish is that b1 doesn't intersect with r4 or c7 ... so no finned (non-sashimi) version can ever exist. I'm sure there are many many others like that.

Of course there are. For example you can interpret every turbot fish as a sashimi x-wing:

Code: Select all

 .  .  . | .  .  . | .  /  .
 .  .  . | .  *  . | .  #  .
 .  .  . | .  .  . | .  /  .
---------+---------+---------
 .  .  . | .  .  . | .  /  .
 .  .  . | .  .  . | .  /  .
 .  .  . | .  .  . | .  /  .
---------+---------+---------
 .  .  . | .  .  . | .  x  .
 /  /  / | /  x  / | x  /  /
 .  .  . | .  .  . | .  /  .


This sashimi mutant x-wing would be r8c8/c5b9 with fin r2c8. But the missing vertex c8/c5 just doesn't exist, it's imaginary. That's when I realised that turbot fish are really some kind of fish.

Or shall we maybe search for another name for these finned degenerating fish, that can't be completed to real finned ones? Because I know it's hard to imagine the underlying fish pattern.

[tarek]

@tarek: I think I'm well within your definition, because two x-wings are not of the same size as a jellyfish.

Yes, my comment about the base sector having only a fin is not true..........

what I meant is that if the fins were removed then a finless equivalent is not possible (degeneration to smaller fish is not the requirement)---That is what was intended by the term when it was introduced.......

Maybe that all sashimi are degenerative abu the reverse is not true.........

A terms update is needed to clarify this......

Is it just me, because i get the feeling that I'm alone on this ????

tarek

[daj95376]

I nominate that Kraken be dropped from the Shape of Fish category. No one wants to use it, and it makes the definition of fish simpler because every other shape is restricted to a matching number of sectors.

Do I hear a second to my nomination?

[ronk]

Do I hear a second to my nomination?

Not from me, not yet anyway. If we haven't already, I'm certain we'll encounter single-digit deductions that can be explained with fish, but only with the "life support" of at least one strong link -- strong inference, actually.

But I might second a nomination to keep the shape and change the name.

[ronk]

This dilemma is from one of daj95376's puzzles.

Code: Select all

....32.142.17.4.3..93.....79.....4.....671.....6.....36.....32..2.3.86.983.26.... #E084 5

After SSTS and an xyz-wing for r5c2<>5:

 7   6  *58  |-589  3   2   |*589 1   4
 2  *58  1   | 7    589 4   |*89  3   6
 4   9   3   |#158 #158 6   | 2  *58  7
-------------+--------------+------------
 9   7   2   | 58   58  3   | 4   6   1
 3  *48 *458 | 6    7   1   |*58  9   2
 15 *158 6   | 4    2   9   | 7   58  3
-------------+--------------+------------
 6   14  7   | 19   149 5   | 3   2   8
 15  2   45  | 3    14  8   | 6   7   9
 8   3   9   | 2    6   7   | 1   4   5

 sashimi mutant jellyfish r3c7b14\r15c2b3 plus fin r3c45, implies r1c4<>8

Looking at only the 8s:

Code: Select all

 .  . *8 | -8  .  . | *8  .  .
 . *8  . |  .  8  . | *8  .  .
 .  .  . | #8 #8  . |  . *8  .
---------+----------+----------
 .  .  . |  8  8  . |  .  .  .
 . *8 *8 |  .  .  . | *8  .  .
 . *8  . |  .  .  . |  .  8  .
---------+----------+----------
 .  .  . |  .  .  . |  .  .  .
 .  .  . |  .  .  . |  .  .  .
 .  .  . |  .  .  . |  .  .  .

And converting to an exemplar showing the empty cells:

Code: Select all

 X *X  X | ** ** ** | *X  *  *
 /  X  / |  .  .  . |  X  *  *
 /  /  / |  #  #  / |  /  X  X
---------+----------+----------
 /  X  / |  .  .  . |  /  .  .
 X *X  X |  *  *  * |  X  *  *
 /  X  / |  .  .  . |  /  .  .
---------+----------+----------
 .  *  . |  .  .  . |  /  .  .
 .  *  . |  .  .  . |  /  .  .
 .  *  . |  .  .  . |  /  .  .

Only the ** exclusions are valid when a fin cell is true

Based on just the empty cells -- the hidden pattern -- the templates technique indicates r1c89<>8 would also be valid, if there were candidates of course. It's obvious that r1c89=8 would cause cascading locked candidates leaving no candidate available in c7.

I've stared at this diagram for at least an hour now, and can't see an explanation that doesn't use contradiction. Does anyone see one