Re: [Computer-go] Komi 6.5/7.5

[Aja Huang]

2015-11-06 9:41 GMT+00:00 Robert Jasiek :

> On 06.11.2015 10:35, Aja Huang wrote:
>
>> another very strong Chinese pro Shi Yue
>>  (No.3 at Go ratings
>> http://www.goratings.org/, current No.2 in China) said he likes to take
>> White with komi 7.5, but with komi 6.5 in his opinion it's 50-50.
>>
>
> He might as well have expressed the opinion that with 5.5 it was 50-50.
> (Chinese pro: area scoring.)


That's a good point. I should have added that both Ke Jie and Shi Yue were
both assuming Chinese rules using area scoring, in which case the score is
almost always odd.

Aja


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Re: [Computer-go] Komi 6.5/7.5

[Robert Jasiek]

On 06.11.2015 10:47, Aja Huang wrote:

area scoring, in which case the score is almost always odd.


Black wins: odd score
White wins: even score

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Re: [Computer-go] Komi 6.5/7.5

[Kahn Jonas]

On 06.11.2015 10:47, Aja Huang wrote:

area scoring, in which case the score is almost always odd.


Black wins: odd score
White wins: even score


Aja means pre-komi. It's always odd (except special seki).
Jonas
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Re: [Computer-go] Komi 6.5/7.5

[Justin Blank]

I have repeatedly seen people assert that komi must be different for
players of different skill levels, and have repeatedly questioned it, but I
have never seen anyone try to substantiate the claim. People who believe it
find it obvious, but I don't. There are two pieces of evidence that I can
think of:

1) that I believe someone played near-random engines against each other,
and the correct komi was different (I cannot find where that was done). But
that's so far from even DDK play that it's pretty useless.
2) I believe the old OGS (DGS?) forums included an analysis of their games
and what the correct komi was. I cannot confidently quote the results. If
those are the old OGS forums, I don't know if they even exist anymore.

The data from go servers are freely available. Does white have a greater
advantage for weaker players? It doesn't seem so--anecdotally when players
posted their KGS stats, they varied a bit, but didn't seem to have a bias
for White.

Of course, that's anecdata...anyone is welcome to prove or disprove this
old claim by analyzing the stats on KGS, or Tygem or wherever else.

On Thu, Nov 5, 2015 at 2:03 AM, Petri Pitkanen 
wrote:

> Let alone we do not have even sufficient understanding of perfect play to
> say what is correct komi in absolute sense. Nor it is it even meaningful
> concept. Correct komi is a komi that produces about 50/50 result. Obviously
> komi that will result in 50/50 for professionals will probably favour white
> in your average weekend tournaments. Just like in chess 1st move advantage
> is clearly less meanigfull for weaker players than top professionals.
>
> So setting komi is not theroretical but statistical issue
>
> 2015-11-05 0:04 GMT+02:00 Hideki Kato :
>
>> The correct komi value assuming both players are perfect.  Or, black
>> utilize his advantage (maybe in an early stage) perfectly.  Actual
>> players, even strong pros, are not perfect and cannot fully utilize
>> their advantages.  As a conclusion, white is favored.
>>
>> Hideki
>>
>> Aja Huang: 

Re: [Computer-go] Komi 6.5/7.5

[Nick Wedd]

Many years ago, when "auction komi" was tried out at a London Open Go
tournament, I collected statistics on what the winning komi bid was among
players of various strengths. There was a positive correlation between
playing strength and komi.  Of course this does not answer the question, it
just shows that strong humans valued the right to play first more than weak
humans did.

I find Hideki Kato's argument intuitively convincing. Suppose "God's komi"
is *n*, so a game between two perfect players using *n* komi ends in jigo.
But when two imperfect players use *n* komi, they will make imperfect
moves, which will reduce the value of sente, and of komi, and Black won't
(on average) be able to recover the *n* points he has paid.

However, there's a powerful counterargument to the above  I can put the
first black stone on the board as well as any professional can. And now,
assuming I am playing an equally weak human, it's White who suffers most
from the imperfection of our subsequent moves.

Nick

On 5 November 2015 at 11:39, Petr Baudis  wrote:

> On Thu, Nov 05, 2015 at 09:03:38AM +0200, Petri Pitkanen wrote:
> > 2015-11-05 0:04 GMT+02:00 Hideki Kato :
> >
> > > The correct komi value assuming both players are perfect.  Or, black
> > > utilize his advantage (maybe in an early stage) perfectly.  Actual
> > > players, even strong pros, are not perfect and cannot fully utilize
> > > their advantages.  As a conclusion, white is favored.
> >
> > Let alone we do not have even sufficient understanding of perfect play to
> > say what is correct komi in absolute sense. Nor it is it even meaningful
> > concept. Correct komi is a komi that produces about 50/50 result.
> Obviously
> > komi that will result in 50/50 for professionals will probably favour
> white
> > in your average weekend tournaments. Just like in chess 1st move
> advantage
> > is clearly less meanigfull for weaker players than top professionals.
>
> I find the notion above really counterintuitive, personally.
>
> Do you have any statistical evidence for this?  I.e. increasing portions
> of white wins in even games as the player rating decreases?
>
> Petr Baudis
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Re: [Computer-go] Komi 6.5/7.5

[Petri Pitkanen]

I do doubt that there is sufficient data available on Go as it is not
popular enough. But lets face it 7 points guaranteed profit is way easier
to utilize than initiative.

For chess it clearly visible quotation from wikipedia
"database between players with similar Elo ratings, commissioned by GM András
Adorján , showed
that as the players' ratings went up, the percentage of draws increased,
the proportion of decisive games that White won increased, and White's
overall winning percentage increased.[15]
 For
example, taking the highest and lowest of Adorján's rating categories of
1669 games played by the highest-rated players (Elo ratings 2700 and
above), White scored 55.7% overall (W26.5 D58.4 L15.2), whereas of
34,924 games played by the lowest-rated players (Elo ratings below 2100),
White scored 53.1% overall (W37.0 D32.1 L30.8)."
A clear difference and even the lowest category is pretty strong. Around
Elo 1500 1st move probably means next to nothing

Why would it be any different in Go? I think 1st move advantage is far less
for weak players Go than in chess, because doing a Null move is far  easier


2015-11-05 13:39 GMT+02:00 Petr Baudis :

> On Thu, Nov 05, 2015 at 09:03:38AM +0200, Petri Pitkanen wrote:
> > 2015-11-05 0:04 GMT+02:00 Hideki Kato :
> >
> > > The correct komi value assuming both players are perfect.  Or, black
> > > utilize his advantage (maybe in an early stage) perfectly.  Actual
> > > players, even strong pros, are not perfect and cannot fully utilize
> > > their advantages.  As a conclusion, white is favored.
> >
> > Let alone we do not have even sufficient understanding of perfect play to
> > say what is correct komi in absolute sense. Nor it is it even meaningful
> > concept. Correct komi is a komi that produces about 50/50 result.
> Obviously
> > komi that will result in 50/50 for professionals will probably favour
> white
> > in your average weekend tournaments. Just like in chess 1st move
> advantage
> > is clearly less meanigfull for weaker players than top professionals.
>
> I find the notion above really counterintuitive, personally.
>
> Do you have any statistical evidence for this?  I.e. increasing portions
> of white wins in even games as the player rating decreases?
>
> Petr Baudis
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Re: [Computer-go] Komi 6.5/7.5

[Christoph Birk]

On Nov 5, 2015, at 4:44 AM, Nick Wedd  wrote:
> However, there's a powerful counterargument to the above  I can put the first 
> black stone on the board as well as any professional can. And now, assuming I 
> am playing an equally weak human, it's White who suffers most from the 
> imperfection of our subsequent moves.

But White already got the komi ….
Christoph


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Re: [Computer-go] Komi 6.5/7.5

[Petr Baudis]

On Thu, Nov 05, 2015 at 09:03:38AM +0200, Petri Pitkanen wrote:
> 2015-11-05 0:04 GMT+02:00 Hideki Kato :
> 
> > The correct komi value assuming both players are perfect.  Or, black
> > utilize his advantage (maybe in an early stage) perfectly.  Actual
> > players, even strong pros, are not perfect and cannot fully utilize
> > their advantages.  As a conclusion, white is favored.
> 
> Let alone we do not have even sufficient understanding of perfect play to
> say what is correct komi in absolute sense. Nor it is it even meaningful
> concept. Correct komi is a komi that produces about 50/50 result. Obviously
> komi that will result in 50/50 for professionals will probably favour white
> in your average weekend tournaments. Just like in chess 1st move advantage
> is clearly less meanigfull for weaker players than top professionals.

I find the notion above really counterintuitive, personally.

Do you have any statistical evidence for this?  I.e. increasing portions
of white wins in even games as the player rating decreases?

Petr Baudis
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Re: [Computer-go] Komi 6.5/7.5

[Stefan Kaitschick]

I agree with Robert. 7 is still a hot candidate for all board sizes.

Stefan
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Re: [Computer-go] Komi 6.5/7.5

[Petri Pitkanen]

Wrong kind of information if the issue is komi(or white win rate) vs
streng. EGD seems to have something but with grabby interface. So to get
any meaninfull data one would have request

Nothing as useful as chess-results
http://www.chess-results.com/tnr184639.aspx?lan=1=2=1=821 exists
where a relatively simple webspider could collect the information. It has
been done for players over 2000 and it shows that value of tempo increases
with players skill. Really no reason to doubt that in go. But no easy way
of getting the data exist.

KGS information would be useful but would need to be collected by the site
operator.  Webspider could overload the system and no interface exist that
would be usefull for collecting the data





2015-11-05 18:26 GMT+02:00 Michael Alford :

> On 11/5/15 7:19 AM, Petr Baudis wrote:
>
> On Thu, Nov 05, 2015 at 02:42:20PM +0200, Petri Pitkanen wrote:
>>
>
> I do doubt that there is sufficient data available on Go as it is not
>>> popular enough.
>>>
>>
>>How much data is enough?
>>
>
> May I suggest Remi's excellent goratings.org for data?
>
> Michael
>
> --
>
> http://en.wikipedia.org/wiki/Pale_Blue_Dot
>
>
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Re: [Computer-go] Komi 6.5/7.5

[Justin Blank]

Of course. You always use win rate, never margin for that type of analysis.

On Nov 5, 2015, at 9:57 AM, Darren Cook  wrote:

>> Of course, that's anecdata...anyone is welcome to prove or disprove this
>> old claim by analyzing the stats on KGS, or Tygem or wherever else.
> 
> Don't forget the distortion due to people knowing the komi, and playing
> to win, rather than playing to maximize their score.
> 
> Darren
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Re: [Computer-go] Komi 6.5/7.5

[Erik van der Werf]

We know the true values for some small boards that were solved, and what
some strong human players believed those values should be before they were
solved. I think that for all cases the humans where either correct, or
under-estimating. I don't remember any over-estimations.

Here are some cases where humans underestimated:

size human migos
2x11   4  6
3x75 21
4x61  8
4x74 28
5x62  4

For more results see: http://erikvanderwerf.tengen.nl/mxngo.html

Perhaps this can be considered an indication that weaker players tend to
benefit less from the first player advantage.

Best,
Erik


On Thu, Nov 5, 2015 at 3:35 PM, Justin Blank  wrote:

> I have repeatedly seen people assert that komi must be different for
> players of different skill levels, and have repeatedly questioned it, but I
> have never seen anyone try to substantiate the claim. People who believe it
> find it obvious, but I don't. There are two pieces of evidence that I can
> think of:
>
> 1) that I believe someone played near-random engines against each other,
> and the correct komi was different (I cannot find where that was done). But
> that's so far from even DDK play that it's pretty useless.
> 2) I believe the old OGS (DGS?) forums included an analysis of their games
> and what the correct komi was. I cannot confidently quote the results. If
> those are the old OGS forums, I don't know if they even exist anymore.
>
> The data from go servers are freely available. Does white have a greater
> advantage for weaker players? It doesn't seem so--anecdotally when players
> posted their KGS stats, they varied a bit, but didn't seem to have a bias
> for White.
>
> Of course, that's anecdata...anyone is welcome to prove or disprove this
> old claim by analyzing the stats on KGS, or Tygem or wherever else.
>
> On Thu, Nov 5, 2015 at 2:03 AM, Petri Pitkanen  > wrote:
>
>> Let alone we do not have even sufficient understanding of perfect play to
>> say what is correct komi in absolute sense. Nor it is it even meaningful
>> concept. Correct komi is a komi that produces about 50/50 result. Obviously
>> komi that will result in 50/50 for professionals will probably favour white
>> in your average weekend tournaments. Just like in chess 1st move advantage
>> is clearly less meanigfull for weaker players than top professionals.
>>
>> So setting komi is not theroretical but statistical issue
>>
>> 2015-11-05 0:04 GMT+02:00 Hideki Kato :
>>
>>> The correct komi value assuming both players are perfect.  Or, black
>>> utilize his advantage (maybe in an early stage) perfectly.  Actual
>>> players, even strong pros, are not perfect and cannot fully utilize
>>> their advantages.  As a conclusion, white is favored.
>>>
>>> Hideki
>>>
>>> Aja Huang: 

Re: [Computer-go] Komi 6.5/7.5

[Petr Baudis]

On Thu, Nov 05, 2015 at 02:42:20PM +0200, Petri Pitkanen wrote:
> I do doubt that there is sufficient data available on Go as it is not
> popular enough.

  How much data is enough?  The games from KGS alone ought to be in
millions, and even EGD must carry at least tens of thousands of serious
tournament games.  A trend ought to be visible there, if you want to
substantiate that argument.

> But lets face it 7 points guaranteed profit is way easier
> to utilize than initiative.

  But is it?  I'm not that strong myself (EGF 2k) but I'm fine with
initiative.  It depends on playing style as much as anything.  But
others in this thread made my argument better.

Petr Baudis
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Re: [Computer-go] Komi 6.5/7.5

[Kahn Jonas]

Of course. You always use win rate, never margin for that type of analysis.


Problem is, this is not relevant unless we have games with different
komi.
The winrate depends as much on the width of the distribution as on the
median. Hence for weak players, it may go closer to 50%, even if the
value of the komi that would be right gets farther away. More or less
the only relevant information at fixed komoi would be if the winrate is
more than 50% above (or below) a certain level, and less than 50% below
(or above) it.

Jonas
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Re: [Computer-go] Komi 6.5/7.5

[Petri Pitkanen]

and in Go one move advantage need that your 1st pro-level mode works
together with your subsequent non-pro-moves

2015-11-05 14:55 GMT+02:00 Christoph Birk :

>
> On Nov 5, 2015, at 4:44 AM, Nick Wedd  wrote:
> > However, there's a powerful counterargument to the above  I can put the
> first black stone on the board as well as any professional can. And now,
> assuming I am playing an equally weak human, it's White who suffers most
> from the imperfection of our subsequent moves.
>
> But White already got the komi ….
> Christoph
>
>
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Re: [Computer-go] Komi 6.5/7.5

[Hideki Kato]

The correct komi value assuming both players are perfect.  Or, black 
utilize his advantage (maybe in an early stage) perfectly.  Actual 
players, even strong pros, are not perfect and cannot fully utilize 
their advantages.  As a conclusion, white is favored.

Hideki

Aja Huang: 

Re: [Computer-go] Komi 6.5/7.5

[Petri Pitkanen]

Let alone we do not have even sufficient understanding of perfect play to
say what is correct komi in absolute sense. Nor it is it even meaningful
concept. Correct komi is a komi that produces about 50/50 result. Obviously
komi that will result in 50/50 for professionals will probably favour white
in your average weekend tournaments. Just like in chess 1st move advantage
is clearly less meanigfull for weaker players than top professionals.

So setting komi is not theroretical but statistical issue

2015-11-05 0:04 GMT+02:00 Hideki Kato :

> The correct komi value assuming both players are perfect.  Or, black
> utilize his advantage (maybe in an early stage) perfectly.  Actual
> players, even strong pros, are not perfect and cannot fully utilize
> their advantages.  As a conclusion, white is favored.
>
> Hideki
>
> Aja Huang: 

Re: [Computer-go] Komi 6.5/7.5

[Erik van der Werf]

I think he's right. I'm fairly sure 7.5 is a second-player win on 9x9,
and for larger boards intuitively it makes sense that the komi should
be the same or lower. Also, we know that perfect komi is an integer,
for area scoring the likely candidates are 5 and 7, and for territory
scoring (and some unlikely area scoring cases) we also have 6. The
fraction is just deciding who shall have the advantage in breaking
ties.

Erik


On Wed, Nov 4, 2015 at 1:59 PM, Aja Huang  wrote:
> Hi all,
>
> As you might know the Chinese professional player Ke Jie is like an erupting
> volcano, triumphant in many domestic and international Go competitions.
>
> In the interview at
>
> http://sports.sina.com.cn/go/2015-11-04/doc-ifxkhqea3033663.shtml
>
> Ke Jie said in his opinion on 19x19 komi 6.5 or 7.5 favors White. That seems
> consistent to MCTS's behavior? i.e. on the empty board, with komi 7.5,
> Black's win rate is usually between 46% and 48% meaning White is ahead. As
> the current top pro, Ke Jie's viewpoint is very interesting. :)
>
> Aja
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Re: [Computer-go] Komi 6.5/7.5

[Robert Jasiek]

On 04.11.2015 13:59, Aja Huang wrote:

Ke Jie said in his opinion on 19x19 komi 6.5 or 7.5 favors White.


Go theoretical considerations (see Joseki 2 - Strategy, chapter 4.4.1) 
estimate the per move value of the first move as ca. 14 points, so 
suggest the komi 7.


Pro game statistics, with the exception of Japanese 2 day games, suggest 
that 6.5~7.5 is closer to 50% than 5~6.



That
seems consistent to MCTS's behavior? i.e. on the empty board, with komi
7.5, Black's win rate is usually between 46% and 48% meaning White is
ahead.


No, this first of all means that MCT should study 7 more.

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