No 2 Games Alike?

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Do you think it is possible for 2 games to be exactly alike?

Yes
10
32%
No
14
45%
Maybe
7
23%
 
Total votes: 31

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HermanHiddema
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Re: No 2 Games Alike?

Post by HermanHiddema »

badukJr wrote:
HermanHiddema wrote:Actually, the question was "what is the likelihood". The word possible does not even appear in the original post, the word impossible is used just once.


No, I don't think so
Image

I don't see "What is the likelihood" at all. It is "Do you think it is possible that 2 games are alike?"



I was referring to the Original Post. The first one, the one where hailthorn explains what he means with his question.

My statistics are very flawed. Realistically, the tree of good games is many orders of magnitude bigger. Although there are points where there is an "only move", there are also many points where there are a dozen choices that are equally valid. The concept of miai is not nonsense.


Maybe. Or maybe there is perfect play. We don't know yet. Looking at CrazyStone analysis, typically he strongly prefers only one move most of the time. I think as bots get stronger this becomes very interesting area of research.



Of course there is perfect play. But, given that there are at least 10^(10^48) possible games, and that there are only 723 possible scores (under area scoring, anything from B+361 to W+361), there are a mindblowing number of games that will result in each score. The number of perfect games is extremely high.

I don't know what calculation you used, but assuming every game is a completely independent event, the formula for calculating the probability that two games out of 68000 are the same in a set of 2^41 possible games is:

1 - e^-(68000^2/2^42)

Which is about 0.1%

This is called a Birthday attack in cryptographic terms. The reason that 68000 gets squared here is because each game can match each other game, so there are 68127*68126 pairs of games that might be the same.

Of course, professional games are not independent events. Professionals study each other's games, play the same joseki or fuseki, they copy each other. That makes the probability of matching openings much higher.


Still, don't you think its quite interesting that something that has only a 0.1% chance of happening has happened twice within the set? And maybe more?


No, because the size of the set, 2^41, is complete and utter nonsense. So that number, 0.1% is completely meaningless.

The important thing, the only thing that is of any meaning at all with respect to the 40 move common openings found, is that pro games are not independent. Therefore, applying statistics to calculate the probability of a common opening is impossible.
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Re: No 2 Games Alike?

Post by TMark »

There are two more interesting games (if I can get this to work), which also involved mirror go and Go Seigen. Here's the first:



And the second:



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Re: No 2 Games Alike?

Post by Mef »

TMark wrote:There are two more interesting games (if I can get this to work), which also involved mirror go and Go Seigen. Here's the first:

Best wishes.



I find it interesting that white won the first game, yet was the first to deviate from the original record (and he ends up losing the second game!). Perhaps he felt he found a trap in the post-mortem that he wanted to avoid walking into?
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Re: No 2 Games Alike?

Post by wjamie »

With the number of players in it and the number of repetitions being done in its advantage, I would say that there is probably a few games that have been repeated already, or how they were played.

Though when you think of it vis-a-vis, the idea seems to far fetched but when you get to it statistically, there is a probability, but not something close to having confidence over.
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Re: No 2 Games Alike?

Post by Mef »

wjamie wrote:With the number of players in it and the number of repetitions being done in its advantage, I would say that there is probably a few games that have been repeated already, or how they were played.

Though when you think of it vis-a-vis, the idea seems to far fetched but when you get to it statistically, there is a probability, but not something close to having confidence over.



After giving it some more thought....I think there's actually a reasonable chance there have been two identical games, but I think it would only be possible with an early joseki trap. For instance - four 4-3 points get played, black makes a fatal mistake in the first corner sequence, then resigns. Once you get past early corner sequences, I think the likelihood of unintentional identical games will quickly drop to essentially zero. It's hard enough when two players are intentionally trying to replicate a game to get all the moves in the right order (example - reviewing it after playing) especially once you get into endgame.
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Re: No 2 Games Alike?

Post by mafidufa »

Mef wrote: ...to get all the moves in the right order...


What if you throw this out and simply look for two games with the same end-position? I don't think there are any (other than very early resignations) but it makes for a slightly easier condition to fulfill.
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Re: No 2 Games Alike?

Post by tchan001 »

First move on KGS automatch on 4-4, opp loses connection and game counts as an escape and later as a forfeit.
I think there is a high probability that there would be many more than just 2 of these games around.
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Re: No 2 Games Alike?

Post by Gegenzeit »

Celebrir wrote:I believe even if two game would be completly the same from order of moves and time to used in thinking at every move there would still have been other thoughts ins the players mind. Therefore it's impossible for me to think of 2 games which are alike.
Sorry if that's off the questions but that's what jumps to my mind while thinking about it ;)


That one is actually a very profound thought!
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