Purpose of and rationale behind Go Markers U+2686 to U+2689

[Martin J. Dürst]

On 2016/03/10 07:52, Ken Whistler wrote:
> I don't know the answer to this. But I suspect that that the source
> was from one of the collection of fonts associated with the STIX
> project research that led to the collection of mathematical symbols
> additions noted in L2/01-067 (superseded by L2/01-142), as well
> as the earlier mathematical symbols proposals with the bulk of
> the symbols that were added to Unicode 3.2.
>
> Given that context, it is, indeed, most likely that the symbols were
> associated with some publication(s) in game theory, rather than
> with professional Go notations per se. See, for example,
> Mathematical Go: Chilling Gets the Last Point:
>
> http://www.amazon.com/Mathematical-Go-Chilling-Gets-Point/dp/1568810326

I own and have read the actual book. For examples of the characters 
mentioned, please see e.g. pp. 17, 21,.... I think the grey stones in 
the earlier proposal were left out because in the book, there are board 
diagrams with e.g. 1/4 of a stone gray,...

So yes, these symbols are used for for mathematical research of the game 
of Go, and not as far as I know for actual notation. The research is in 
combinatorial game theory, where very weird infinitesimal numbers (e.g. 
greater than 0 but smaller than any positive number!) are often used. 
These numbers are part of the 'Surreal Numbers' introduced in Donald 
Knuth's 1974 book of the same name.

And while I have only seen the symbols in mathematical work, that theory 
can be highly relevant in actual endgames, and at least professional 
players should be aware of it (the theory, not the symbols), because 
often games can be decided by the last point won or lost in the endgame.

> I don't see black/white circles with dots in the bit of that publication
> scanned on Amazon, but it does use a black circle with a delta
> symbol as part of the game notation for discussion, as well as
> black and white circles with numbers, denoting sequences of stone
> placements.

As James said, the circles with numbers are extremely widely used; it's 
the basic way to show games (because stones are not moved around and 
only very rarely removed from the board, the main notation for Go is not 
a list of moves with coordinates (as e.g. in Chess), but just a diagram 
of the final (or intermediate) board position with every move labeled 
with a number. But because these numbers can go up to the 200s, it 
doesn't make sense to register them all as characters (one would need 
over 500!).

Regards,   Martin.

> But to know for sure, you would probably have to get confirmation
> of original sources from Barbara Beeton and/or Patrick Ion,
> who collected together symbol candidates from a multitude
> of print sources back in the 1998 - 2001 time frame.
>
> --Ken
>
> On 3/9/2016 1:17 PM, Ori Avtalion wrote:
>> Unicode includes the following symbols as "Go Markers":
>> * U+2686 ⚆ WHITE CIRCLE WITH DOT RIGHT
>> * U+2687 ⚇ WHITE CIRCLE WITH TWO DOTS
>> * U+2688 ⚈ BLACK CIRCLE WITH WHITE DOT RIGHT
>> * U+2689 ⚉ BLACK CIRCLE WITH TWO WHITE DOTS
>>
>> It is unclear what they are for. I hope someone could explain.
>>
>> 1) I could not find any Go notation that uses dots inside the stones.
>> 2) Why are there no symbols for white/black stones without dots?
>> 3) An earlier proposal [1] suggested additional symbols:
>>    * GRAY CIRCLE WITH GRAY DOT RIGHT
>>    * GRAY CIRCLE WITH GRAY TWO DOTS
>>    * GRAY FILLED CIRCLE WITH WHITE DOT RIGHT
>>    * GRAY FILLED CIRCLE WITH WHITE TWO DOTS
>> what was their purpose? Any why are Go Markers proposed as
>> "Mathematical symbols"? Are they meant for mathematical research of
>> the game of Go and not for actual notation?
>>
>> [1] http://www.unicode.org/L2/L2001/01067-n2318-mathadd4.pdf
>>
>> Thanks in advance!
>>
>>
>
> .
>