# [Computer-go] Practical significance?

Leandro Marcolino leandromarcolino at gmail.com
Wed Nov 28 12:03:36 PST 2012

```Thank you all for your comments!.. :) It helped me to get some very good
insights!.. hehe :) I am not closing the thread, in case someone has more
opinions, etc...

> When you said a "23% difference" did you mean the win-ratio is 61.5:38.5?

Well, basically I mean that in 1000 games, system A1 can win about 300
games (30%) against B, while A2 can win about 530 games (53%) against B. So
I calculate a difference of 23% between A1 and A2. As Ingo noted, this
assumes transitivity, that may not always happen in real life, but as Don
said, it can be a "good" approximation.... In a more strict interpretation,
A2 would be 23% better "when playing against B"...

Thanks,
Leandro

On Mon, Nov 26, 2012 at 4:18 PM, Mark Boon <tesujisoftware at gmail.com> wrote:

> On Mon, Nov 26, 2012 at 1:09 PM, Kahn Jonas <jonas.kahn at math.u-psud.fr>
> wrote:
> >
> > That's not too far from the winrates between Cho Hunhyun and Seo
> > Bongsoo.
> > The latter is far from the glory of the former, but when they were by
> > far the two strongest players in Korea, Seo has won his share of titles.
> >
>
> To be honest, I don't have solid statistics to back it up. Having said
> that, I'd be surprised if the real winning percentage of Cho Hunhyun
> vs. Seo Bongsoo would be 62:38. How often did they play?
>
> I remember in the old days the Go World magazine would publish the
> winning rates of the top players in Japan. If I remember correctly,
> the handful of players dividing the bulk of the titles over a decade
> would still only have a winning rate of about 55% over the whole year.
> Of course this is partly caused by top players playing among top
> players. But they also still play a lot against lower-tier players in
> for example the qualifying rounds of tournaments.
>
> The other thing you have to take into account is this: if a 'weaker'
> player played lots of 5-game matches against a top player, he might
> occasionally win one set. But the qualifying systems of these
> tournaments are so extensive that the weaker player very rarely makes
> it through. So the weaker player doesn't get a lot of shots to try.
> Occasionally it happens that someone wins a title as a one-time off.
> Most titles are divided among a small number of top players while the
> majority of 9p players never win any. But I'm hazarding the guess that
> if you'd pit a top player against a 'weaker' 9p player who never won
> anything major, the winning percentage of the top player would be less
> than 62%. But it's still only a guess, I admit. If someone has
> statistics at hand I'd be interested to see.
>
> Mark
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