The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|.9.|.5.|
 |7.8|63.|..2|
 |.4.|5..|6..|
 |---+---+---|
 |.6.|85.|...|
 |.75|..9|.26|
 |...|7.6|81.|
 |---+---+---|
 |.1.|.8.|.6.|
 |.83|.67|5..|
 |5..|...|.7.|
 *-----------*


Play/Print this puzzle online

[SteveG48]

Code: Select all

 *------------------------------------------------------------*
 | 6     2-3   12    | 24    9     8     | a137   5     1347  |
 | 7     5     8     | 6     3     14    | a19    49    2     |
 | 1239  4     129   | 5     7     12    |  6     8     13    |
 *-------------------+-------------------+--------------------|
 | 12    6     124   | 8     5     24    | a79    3     79    |
 | 8     7     5     | 3     1     9     |  4     2     6     |
 | 239  d239   249   | 7    c24    6     |  8     1     5     |
 *-------------------+-------------------+--------------------|
 | 249   1     7     | 29    8     5     |  239   6     349   |
 | 249   8     3     | 129   6     7     |  5     49    149   |
 | 5   bc29    6     | 1249 b24    3     | a129   7     8     |
 *------------------------------------------------------------*


(3=1279)r1249c7 - 2r9c25 = (29)r6c5,r9c2 - (2|9=3)r6c2 => -3 r1c2 ; stte

[eleven]

Same as almost x-wing.

Code: Select all

 *--------------------------------------------------------------*
 |  6     a2-3   12    |  24     9    8    | b137   5    1347   |
 |  7      5     8     |  6      3    14   | b19    49   2      |
 |  1239   4     129   |  5      7    12   |  6     8    13     |
 |---------------------+-------------------+--------------------|
 |  12     6     124   |  8      5    24   | b79    3    79     |
 |  8      7     5     |  3      1    9    |  4     2    6      |
 |  239   #239   249   |  7     #24   6    |  8     1    5      |
 |---------------------+-------------------+--------------------|
 |  249    1     7     |  29     8    5    |  239   6    349    |
 |  249    8     3     |  129    6    7    |  5     49   149    |
 |  5     #29    6     |  1249  #24   3    | b129   7    8      |
 *--------------------------------------------------------------*

2r1c2 = xwing 2r69c25 - (2=1973)r1249c7 => -3r1c2, stte

[SpAce]

Code: Select all

.------------------.-------------------.------------------.
| 6     a[2]3  12  | a2[4]     9    8  | b137    5   1347 |
| 7       5    8   |  6        3    14 |  19     49  2    |
| 1239    4    129 |  5        7    12 |  6      8   13   |
:------------------+-------------------+------------------:
| 12      6    124 |  8        5    24 |  79     3   79   |
| 8       7    5   |  3        1    9  |  4      2   6    |
| 239     239  249 |  7        24   6  |  8      1   5    |
:------------------+-------------------+------------------:
| 249     1    7   |  29       8    5  | b239    6   349  |
| 249     8    3   |  129      6    7  |  5      49  149  |
| 5       9-2  6   |  129-4  c(24)  3  | c1(2)9  7   8    |
'------------------'-------------------'------------------'

(24=3)r1c24 - (32)r17c7 = (24)r9c75 => -2,4 r9c24; stte

[SpAce]

Same as almost x-wing.
2r1c2 = xwing 2r69c25 - (2=1973)r1249c7 => -3r1c2, stte

That's a very nice solution. Personally I'd just get rid of the text and the wasteful ALS:

(2)r1c2 = c25\r69 - r9c7 = (23)r71c7 => -3 r1c2; stte

That way it's using just two digits and one fewer cell, making it objectively more efficient and subjectively prettier and more readable. Also, since a standard fish notation (UFG) exists, why not use it? I think it's perfectly suited for chaining purposes, being unambiguous and mostly very simple and concise (for finned fishes I prefer the shorter obi-notation). I'd be using it all the time if I ever spotted useful almost fishes

[SteveG48]

Also, since a standard fish notation (UFG) exists, why not use it?

One reason would be that a lot of people don't know it. I understood Eleven's notation perfectly. I understood what you wrote only because of the context. My bad, I suppose.

[SpAce]

Also, since a standard fish notation (UFG) exists, why not use it?

One reason would be that a lot of people don't know it. I understood Eleven's notation perfectly. I understood what you wrote only because of the context. My bad, I suppose.

Well, yes and no. Few regulars (who've all been around many times longer than myself) seem to be aware of the UFG notation, so it's not unexpected at all. SteveC is the notable exception, though I'm not sure if his kraken 1-fishes make the best case for it It's just a bit surprising, considering how long the UFG has been around and how much good work has been devoted to it. That kind of underscores my point, though. If no one uses that notation, then no one ever learns to (even) read it, even though it's very easy. One of my pet peeves with Hodoku is that it almost does but not quite (it skips the '\' for some reason), even though it's otherwise very UFG compliant.

Why should anyone learn it? Because it's far superior to any ad hoc fish notations I've seen. It actually makes sense and communicates perfectly what a fish is all about (base and cover sets), in a concise manner that fits well within Eureka. The '\' differentiates it nicely so there's no confusion with other patterns. Unlike my prior experimenting with the 3D-notation, it's not hard to read at all. If you see '\' you know it's a fish, and the rest tells you everything about it, unambiguously and without lengthy words. What's not to like?

Sure, eleven's notation was very understandable because it used a word, but without it the mere cell pattern didn't make any sense from a fish point of view (not differentiating between base and cover sets, and listing them in the wrong order anyway). "X-Wing" is a short single word and the simplest fish, so I'm not too bothered by it, but proper fish names can also be awfully long and complicated. The right place for them is in the intro to the solution (e.g. "almost x-wing", just like eleven did), not in the chain itself. That should be enough to warn the reader to expect seeing fish notation in the chain.

In general, I hate all extra text within chains unless it's for a pattern that actually requires it. I don't see any reason for it with fishes, because a perfectly good notation exists that covers every base (no pun intended). It's the same reason (to a lesser extent) as why I don't like the superfluous 'HP' markers etc. It's just clutter, kind of like trivial comments in a program when the code is (or should be) mostly self-documenting. Yet, even if one insists on using the fish name in the chain, why not use the UFG notation for the cell pattern anyway (for basic fishes it's trivial)? I'd be fine with that compromise.

Last but not least, fishes are one of the very few things that actually need their own notation, because some of them can't be expressed as chains/loops (or even nets easily).

PS. I suggested the same first here. 100% of the feedback was positive