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Topic: Short notation for Arimaa games and positions (Read 10483 times) |
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omar
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Short notation for Arimaa games and positions
« on: Dec 25th, 2008, 7:10am » |
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For quite some time now I've been thinking on and off about an easier way to convey Arimaa moves and positions to other humans. The current notation is quite verbose and was specially designed to make it easy for computers to process. While writing comments in games or chatting during a game I felt the need to express the moves more concisely and quickly. Then while proof reading the Arimaa books Karl and Jean wrote it really felt cumbersome to read the notation. I am sure it was much worse for the authors to actually write it. I had a lot of ideas floating around about a new notation and last night I finally wrote them down. Here is the document defining the short notation.
http://arimaa.com/arimaa/learn/shortNotation.html
Hope I covered everything because this was a bit tricky to define. Feedback is welcomed.
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| « Last Edit: Dec 25th, 2008, 7:11am by omar » |
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #1 on: Dec 25th, 2008, 7:51am » |
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Quote:| the 3rd gold rabbit moves west and then north. To find this rabbit scan the rows from left to right starting with the closest row until you encounter the 3rd gold rabbit. |
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This is a bit ambiguous. Do you scan all of the first nearest row left-to-right before starting on the second row, or globally scan from left-to-right and break ties by which row is closest?
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jdb
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Re: Short notation for Arimaa games and positions
« Reply #2 on: Dec 25th, 2008, 8:42am » |
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PGN style piece disambiguation
http://www.drpribut.com/sports/standard.txt
Quote:8.2.3.4: Disambiguation
In the case of ambiguities (multiple pieces of the same type moving to the same
square), the first appropriate disambiguating step of the three following steps
is taken:
First, if the moving pieces can be distinguished by their originating files,
the originating file letter of the moving piece is inserted immediately after
the moving piece letter.
Second (when the first step fails), if the moving pieces can be distinguished
by their originating ranks, the originating rank digit of the moving piece is
inserted immediately after the moving piece letter.
Third (when both the first and the second steps fail), the two character square
coordinate of the originating square of the moving piece is inserted
immediately after the moving piece letter.
Note that the above disambiguation is needed only to distinguish among moves of
the same piece type to the same square; it is not used to distinguish among
attacks of the same piece type to the same square. An example of this would be
a position with two white knights, one on square c3 and one on square g1 and a
vacant square e2 with White to move. Both knights attack square e2, and if
both could legally move there, then a file disambiguation is needed; the
(nonchecking) knight moves would be "Nce2" and "Nge2". However, if the white
king were at square e1 and a black bishop were at square b4 with a vacant
square d2 (thus an absolute pin of the white knight at square c3), then only
one white knight (the one at square g1) could move to square e2: "Ne2".
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jdb
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Re: Short notation for Arimaa games and positions
« Reply #3 on: Dec 25th, 2008, 8:47am » |
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Quote:Movements are specified using the letters to indicate the piece to move and one or more special characters to indicate direction of sequential steps. The direction characters are +, -, <, > for up, down, left and right. For example:
g 5g e+>>-
specifies that the board is viewed from the gold side and the gold elephant takes four steps moving north, east, east and then south. The side to move specifies which color pieces the letters represent. |
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Maybe consider using n,s,e,w for directions. They are already used in the long form notation, which would make it easier for people to switch between reading the two types of notation.
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jdb
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Re: Short notation for Arimaa games and positions
« Reply #4 on: Dec 25th, 2008, 8:53am » |
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Quote:| The side which the board is being viewed from can be specified before the move or by itself on a single line. The value may be: g, s or n to indicate gold, silver or neutral. In case of neutral the gold player is on the left and the silver player is on the right. If the side to view from is not specified at the start of the move then any previously specified view remains in effect. If no view has previously been specified then the gold side is assumed. |
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I recommend having only one view, probably gold. Having multiple views adds considerably to the state information required to read through a move list. It is a lot easier to play through a move list if the view is constant. It also makes the notation simpler.
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #5 on: Dec 25th, 2008, 9:55am » |
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on Dec 25th, 2008, 8:42am, jdb wrote:| PGN style piece disambiguation |
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The PGN piece disambiguation is seldom needed because the destination square is given, and it is unusual for two pieces of the same type to be able to move to the same square. For Arimaa we have the luxury of being able to dispense with the destination square and reduce it to a single character, but that means rabbit moves will constantly need to be disambiguated, in contrast to pawn moves which are almost never ambiguous. Since it is a different issue I'm not sure we should expect PGN-style to work well for us.
For starters, if we want to indicate that the rabbit on the d-file moves forward, PGN disambiguation would notate that rd+, which Omar has already given the meaning of "dog moves forward, pulling rabbit".
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #6 on: Dec 25th, 2008, 10:03am » |
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on Dec 25th, 2008, 8:47am, jdb wrote:| Maybe consider using n,s,e,w for directions. They are already used in the long form notation, which would make it easier for people to switch between reading the two types of notation. |
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Using cardinal directions was my first reaction as well, but on further consideration I find I am much quicker telling right from left than east from west, and even if I forget my right and left, the symbol itself shows the direction > or <. A second issue with compass directions is that the letter 'e' would stand for east as well as elephant, making it harder to read a move like deeeenen unless we insert spaces, lengthening the notation, as compared to d>e>++, which is readable without spaces.
I take your point about switching between notations. I expect to have difficulty using omar's suggested notation at first, but I think it is worth a try. If it is way easier to use once we get used to it, we may even want to deprecate the long notation.
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| « Last Edit: Dec 25th, 2008, 12:30pm by Fritzlein » |
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #7 on: Dec 25th, 2008, 10:07am » |
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on Dec 25th, 2008, 8:53am, jdb wrote:| I recommend having only one view, probably gold. Having multiple views adds considerably to the state information required to read through a move list. It is a lot easier to play through a move list if the view is constant. It also makes the notation simpler. |
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I quite agree that we should stick to a single perspective. Even if other perspectives are defined, it would be just too confusing to use them. I'll wager that if we actually start using this shorthand in the chat room, anyone who uses silver-perspective shorthand will be pilloried.
There's something odd about making Silver reverse right/left and up/down from his perspective, but we have already been forcing that with the old cardinal directions, and gaining advantage of perspective just doesn't seem worth the confusion caused.
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| « Last Edit: Dec 25th, 2008, 12:30pm by Fritzlein » |
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #8 on: Dec 25th, 2008, 10:13am » |
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Quote:g 33g d2>dc+c*d+d*
specifies that the 2nd gold dog goes east and pushes the silver cat north; the cat is removed; the dog continues north and is also removed. |
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As long as we are going for brevity, an asterisk can indicate that a capture was made without specifying the piece captured. The above move would then become d2>dc+*d+*.
Actually, since we are relying on context to determine lots of other things, the context could also determine whether or not there are captures, making the notation d2>dc+d+ sufficient, but I can see why one might want the redundant information. In chess notation the plus sign for check is redundant but generally useful enough to be justified. So I expect my preference will be to indicate a capture with an asterisk, but leave off the letter of the captured piece.
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| « Last Edit: Dec 25th, 2008, 12:32pm by Fritzlein » |
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omar
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Re: Short notation for Arimaa games and positions
« Reply #9 on: Dec 25th, 2008, 12:38pm » |
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on Dec 25th, 2008, 7:51am, Fritzlein wrote:
This is a bit ambiguous. Do you scan all of the first nearest row left-to-right before starting on the second row, or globally scan from left-to-right and break ties by which row is closest? |
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The first case. I changed the wording as follows now:
Quote:| To find this rabbit scan each row one at a time from left to right starting with the closest row and moving toward further rows until you encounter the 3rd gold rabbit. |
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omar
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Re: Short notation for Arimaa games and positions
« Reply #10 on: Dec 25th, 2008, 1:12pm » |
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on Dec 25th, 2008, 8:47am, jdb wrote:
Maybe consider using n,s,e,w for directions. They are already used in the long form notation, which would make it easier for people to switch between reading the two types of notation.
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The reason for going with symbols was because they are more intuitive. I think there is a bit more processing that humans have to do to map a letter to a direction than to map an arrow symbol to a direction. I was originally going to use ^ for up and v for down, but in some fonts they didn't look good, so I went with + and -.
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jdb
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Re: Short notation for Arimaa games and positions
« Reply #11 on: Dec 25th, 2008, 1:32pm » |
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on Dec 25th, 2008, 1:12pm, omar wrote:
The reason for going with symbols was because they are more intuitive. I think there is a bit more processing that humans have to do to map a letter to a direction than to map an arrow symbol to a direction. I was originally going to use ^ for up and v for down, but in some fonts they didn't look good, so I went with + and -.
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I disagree. The standard directions n,s,e,w are burned into people's brains at a young age.
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omar
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Re: Short notation for Arimaa games and positions
« Reply #12 on: Dec 25th, 2008, 1:38pm » |
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on Dec 25th, 2008, 8:53am, jdb wrote:
I recommend having only one view, probably gold. Having multiple views adds considerably to the state information required to read through a move list. It is a lot easier to play through a move list if the view is constant. It also makes the notation simpler. |
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One of the things I didn't like about the regular notation is that if forced a single view from golds side. Sometimes one would want to show the position diagram from silvers view, but then I have to keep reorienting myself to golds view to follow the notation. Allowing the author to select the view for the notation actually makes it easier to read and write it. The view can be selected so that < means my left, rather than my opponents left.
Giving the ability to change the view at the start of each move may be a bit of an overkill. In actual use I think an author will probably only set the view once and use it for all the moves. However the flexibility is there so I can do something like give golds setup from golds view, give silvers setup from silvers view and then switch to a side neutral view for the rest of the moves.
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Fritzlein
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Re: Short notation for Arimaa games and positions
« Reply #13 on: Dec 25th, 2008, 1:44pm » |
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on Dec 25th, 2008, 1:12pm, omar wrote:I was originally going to use ^ for up and v for down, but in some fonts they didn't look good, so I went with + and -.
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Ooh, now that you mention it, I like caret and vee better than plus and minus. I think you should at least list it as an optional replacement. We should see what people like to use.
In general these theoretical arguments are just a lot of guessing, as you specifically found out. You created one notation, Omar, and when I objected that it was cumbersome you defended its merits. Once you actually started to try to use it in practice, you noticed its defects as well and came up with something more compact for a different purpose.
In fact, that's my attitude for giving moves from Silver's perspective as well. My guess is that people will find the confusion from the same move having two (or three) different notations to be much more of a bother than having directions be inverted for Silver, but that's only a guess, and we will see in practice what people prefer.
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| « Last Edit: Dec 25th, 2008, 1:51pm by Fritzlein » |
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omar
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Re: Short notation for Arimaa games and positions
« Reply #14 on: Dec 25th, 2008, 1:45pm » |
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on Dec 25th, 2008, 9:55am, Fritzlein wrote:
For starters, if we want to indicate that the rabbit on the d-file moves forward, PGN disambiguation would notate that rd+, which Omar has already given the meaning of "dog moves forward, pulling rabbit". |
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Using the file will not always be enough to disambiguate since there could be multiple rabbits on the same file that can move forward. The sequential scan will always work and the number will never be more than 8.
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