Bit arithmetic on Unicode characters?

Garth Wallace gwalla at
Sat Oct 8 20:02:56 CDT 2016

On Sat, Oct 8, 2016 at 9:31 AM, Philippe Verdy <verdy_p at> wrote:

> Markup for rotation is highly underdeveloped, and in this case for chess
> it has its own semantics, it's not just a presentation feature, possibly
> meant for playing on larger boards with more players than 2, and
> distinguished just like there's a distinction between white and black, or
> meant to signal some dangerous positions or candidate target positions for
> the next moves.

Not exactly. Rotation of chess piece symbols is not a presentation feature
(at least as I understand the term), and isn't meant for use with
multiplayer games. The rotated pieces are used in chess problems,
specifically heterodox or "fairy chess" problems, where they stand in for
non-standard pieces. A rotated rook, for instance, means "a piece that is
not a rook but is similar in some respects"; which piece it represents
specifically depends on context. Conventionally, the upside-down queen
represents a "grasshopper" and the upside-down knight a "nightrider", but
otherwise they are assigned on a problem-by-problem basis. This practice
dates back to the early 20th century and was originally so that problem
composers wouldn't have to cut new type for every new piece they invent but
is now traditional.

I also see some additions like florettes, and elephants needed for
> traditional Asian variants of the game, plus combined forms (e.g.
> tower+horse) which are quite intrigating.
> There are also variants rotated 45 degrees.

The florettes are also used in problems, as are the equihoppers (the symbol
that looks a bit like a bow tie or spindle). The compound symbols are found
in problems and in several common variants such as Capablanca Chess and
Grand Chess. The jester's cap is similar. The elephant and fers are used in
shatranj or medieval chess.

> All those are not just meant for display on the grid of a board but in
> discussions about strategies. There are also combining notations added on
> top of chess pieces (e.g. numbering pawns that are otherwise identical, but
> in plain text you can still use notations with superscript digits or
> letters, distinguished clearly from the numbering of grid positions, or by
> adding some other punctuation marks).

I haven't encountered that. It's rarely necessary to differentiate
individual pawns in notation: their moves are so limited that it's usually
obvious which pawn is moving, and there is a standard method of
disambiguating moves by starting square if needed.

> I still don't see in these images the elephants (or other pieces like
> unmovable rocks or rivers, or special pieces added to create handicaps for
> one of the player). I've also seen some chess players using special queens
> by putting a pawn on top of a nother falt pawn, with more limited movements
> than a standard queen. There are also bishops/sorcerers/magicians, eagles,
> dragoons, tigers/lions, rats, dogs/foxes, snakes,
> spiders, soldiers/archers, canons, walls/fortresses, gold/treasures...
> Chess games have a lot of variants with their supporters. Modern movies are
> also promoting some variants.

There are elephants in the proposal, using a shape found in medieval
manuscripts. Rocks and rivers are board features and not found in notation.

> 2016-10-08 17:24 GMT+02:00 Ken Shirriff <ken.shirriff at>:
>> Looking at the image, the idea of the proposal is to include chess piece
>> symbols in all four 90° rotations? Wouldn't it be better to do this in
>> markup than in Unicode? I fear a combinatorial explosion if Unicode starts
>> including all the possible orientations of characters. (Maybe there's a
>> good reason to do this for chess; I'm just going off the image
>> <>
>> .)
The proposal covers this. These have a well-established use in chess
notation, which doesn't apply to non-chess symbols. Markup would be the
wrong way to do this. It's not like, say, electronic schematics where a
diode symbol may be found in any orientation but still always represents a
diode: a rotated queen symbol is specifically *not a queen* but another
piece entirely.

Currently, fairy chess problemists rely on font hacks and PDFs (even for
relatively short texts).
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