Life In 19x19

Posted: **Sun Jan 11, 2015 11:53 am**

Here is a really excellent review by Andrew Jackson and Ryan Li together on one of his earlier games against the young and upcoming Jeremy Chiu

edit: (wow, using the youtube tags are really NOT obvious)

Posted: **Mon Jan 12, 2015 3:21 am**

DrStraw wrote:
Matti wrote:How will the lower places de decided?
Look at the results grid: http://www.usgo.org/aga-professional-results-2014

I had already looked the results before I asked the question. I only figured it out once I read that one player had withdrawn.

Posted: **Mon Jan 12, 2015 6:50 am**

Nice to hear Ryan's comments on that game. I too didn't see that awesome connect-and-die which made the peep to save that cutting stone in the top left not only kill the left stones but also the middle ones too. Though I think Andrew Jackson should ~~shut up occasionally~~ talk less and let Ryan talk more. Having a co-commentator jump in a lot makes sense when the other is bumbling/struggling with English/talking way over the head of the audience but that wasn't the case here. I was surprised though that when Ryan put in that cutting stone originally there was no mention of atari from the outside to sacrifice and make shape as that seemed to make sense with black's previous jumping move.

Posted: **Mon Jan 12, 2015 11:31 am**

pwaldron wrote:
DrStraw wrote:Well, Ryan Li just won through to the finals. I am not sure that was the best result for him. Now he has to play a best of 5 with one game up. Had he lost and won the third game when it would have been a best of 3 and one game up.

While he was not guaranteed to win a third game in this semifinal, and so had to play to win, he has actually made it harder for himself to win the final, even though he is probably considered to be the favorite as he is already one up.
I was wondering the same thing this morning as I got dressed and I sat down to do the math when I had tea. I had thought that the best-of-five must automatically be better for Ryan, thinking that the probability the better player is more likely to win a best-of-n series as n increases and figuring that winning the first game of any series must be good.

As it turns out, it's not the case for realistic situations. If the probability of Ryan beating Eric in an individual game is less than 65% then he is better off with the best-of-three option. There is a crossover where the best-of-five is better: if Ryan's probability of winning a single game is greater than 65% then he's better with the longer series. Of course in that scenario he wins the series more than 90% of the time, so it's not really relevant.

This isn't to say that Ryan isn't the favourite. He looks to have something like a 60-80% chance of winning a best-of-five assuming he's at least as strong as Eric. With the best-of-three, though, he started at 75% and went up from there. Based on ratings it looks like Ryan has about a 70% chance of winning.

I am not exactly sure what is being claimed. For simplicity I'll assume that we are talking about the relative chances of winning a best of three match or a best of five match, given winning the first game.

Let P be the probability of winning a single game and W(N) be the probability of winning the N game match.

For the best of three match:

W(3) = P + P(1-P) = 2P - P^2

For the best of five match:

W(5) = P^2 + 2P^2(1-P) + 3P^2(1-2P+P^2) = 6P^2 - 8P^3 + 3P^4

If W(5) > W(3) then

3P^4 - 8P^3 + 6P^2 > -P^2 + 2P

And

3P^4 - 8P^3 + 7P^2 - 2P > 0

Or

P(P-1)^2(3P-2) > 0

The crossover point is 2/3.

Posted: **Mon Jan 12, 2015 11:38 am**

Bill Spight wrote: I am not exactly sure what is being claimed.

Had he lost his second game in the semi-finals, there would not have been enough time to play a best-of-5 in the finals, so they would have only played a best-of-3 instead. So he would only have to win the next two games. Otherwise, he has to win the next three. At least one fewer games overall.

Posted: **Mon Jan 12, 2015 11:55 am**

Bill Spight wrote:The crossover point is 2/3.

And that was exactly my point. I doubt (or at least I did when I posted) that Ryan had a 2/3 chance in each game because their AGA ratings were fairly close. Therefore by winning the semifinal quicker I thought he had reduced his chance of winning the final.

Posted: **Mon Jan 12, 2015 12:24 pm**

Uberdude wrote: Though I think Andrew Jackson should ~~shut up occasionally~~ talk less and let Ryan talk more. Having a co-commentator jump in a lot makes sense when the other is bumbling/struggling with English/talking way over the head of the audience but that wasn't the case here.

I often find myself similarly annoyed with radio and talk show personalities, but not so much here. Maybe because I'm only a kyu player and in that regard felt that Andrew brought a lot to the table himself.

If you were able to catch any of the live game commentaries with Andrew and Myungwan Kim 9p (I don't believe the KGS recording was captured), I felt Andrew brought a lot to the table there too. More so than Myungwan Kim's usual co-hosts.

Posted: **Mon Jan 12, 2015 12:50 pm**

There is definitely a place in commentary for someone significantly less knowledgable to act as a foil for the main commentator, and jump in with questions, ask for clarification, ask about alternatives, etc. to provide a voice for the less knowledgable listener who may have the same sorts of questions. If your own skill level is higher than the second commentator's most of their information will seem redundant, but that doesn't mean it's useless to everyone.

Posted: **Wed Jan 14, 2015 2:00 pm**

Uberdude, thanks for the feedback! I'll try and leave more space for my partner in the future... I'm pretty new at this

I think i did a better job when i was commenting with Myungwan, but, not sure.

When i discussed it with Ryan afterwards, he mentioned that he hadn't realized how quiet he was, so i think you make a good point that we can both take to heart

Hopefully we'll improve with practice.

DrStraw: the venue this year was *very* economical. Sure, it's a beach hotel... in Massachusetts in January

. It was -4F in the morning

, and we were practically the only guests... it is also partially supported by the KBA, but that's another story.

Life In 19x19

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