When nigiri, is it better to choose odd or even?

Do people generally tend to grab odd or even number of stones?

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Had to look up nigiri.

First hit resulted in:

Then added weiqi to the search:
Nigiri is a Japanese go term (from the Japanese, lit. “grab”, “grasp”, “squeeze”) adopted into English, referring to the procedure common in Japan at the beginning of an even game to decide who will play the black stones; the equivalent of flipping a coin to determine who kicks off a game of football (source: sensei’s library).

Returning to this important philosophical question: don’t think it matters whether you choose odd or even.

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If your hand is so small that it can only grab one stone, then you always grab an odd number of stones.

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This is actually a pet peeve of a go player I know:

I suppose there is an equal number of even and odd numbers, so you might think there is an equal chance of grabbing an even or odd number of stones. But since hand size is limited, we should consider only relatively small number (say ~20 or less stones). And we may also consider that it’s unlikely that people grab 0 stones.

So his hypothesis is that a random small positive number is odd more often than even (because 0 is excluded, which is an even number). So he always guesses odd (because he prefers black).

But ofcourse, I know he tends to guess odd, so I may grab 0 stones on purpose when we nigiri. He knows that now, so he may guess even against me (making an exception to his rule).

Anyway, I think it’s not that simple, because people grabbing only 1 stone may be equally unlikely as people grabbing 0 stones.

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Isn’t it basically like rock, paper, scissors? In the sense that following a deterministic strategy (e.g. always choosing rock or, in the case of nigiri, even) makes you vulnerable to the respective counter-strategy.

So my guess is the optimal strategy is to choose even with probability (1/2 + delta) and odd with probability (1/2 - delta), where the absolute value of delta is close (or equal) to zero.

The worst-case optimal strategy is clearly to choose even / odd exactly 1/2 of the time.

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In case one isnt sure how nigiri works, just grab 2 stones every single time and you look like you actually have some idea what you’re doing xD

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Nigiri is one of the first things I teach children in my club. It’s quite funny that they tend to grab hands full of stones, so it takes them ages to determine if it’s even or odd :laughing:.

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Perhaps it can be computed with a Poisson distribution (see https://math.stackexchange.com/a/2007252)?

P(even) = (1 + exp(−2λ))/2
P(odd) = (1 - exp(−2λ))/2

With a mean (=λ) of 10, I get:

P(even) = 0.50000000103
P(odd) = 0.49999999897

But I guess this assumes that 0 is not a particularly favoured or unfavoured result.

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It’s good that you teach them that, surprising non-zero amount of competent players try to do the grab with the black stones, in tournaments.

I personally grab like 5 pairs to make it quicker but I’ve seen some pros grab a lot of stones. Maybe they do it a bit performatively on camera (similar to the very slow first move), and count out them slowly too.

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Any calculation similar to this assumes that the person who grabs a handful of stones is doing so randomly. But as you have mentioned before, nothing disallows a person from grabbing a specific amount of stones, and it’s not too difficult to count by feeling the stones with your hand. So in a theoretical sense I believe that Nigiri should be treated as a two-player game with imperfect information.

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I think you’re supposed to just grab a “handful” of stones to make it random.

I don’t think it’s meant to be some kind of psychological Rock Paper Scissors type game. I think it’s just supposed to be an alternative to flipping a coin.

Like I don’t think you’re supposed to plan out “I’ll pick out ten stones this time because I think this person will pick odd” or “picking odd is more common so…” or “there’s a higher chance of somebody grabbing an odd number of stones so…”

Although at the end of the day it doesn’t really matter why the person picking even/odd picks what they do, in the same way it probably doesn’t matter with heads/tails ( unless you think it’s biased, which supposedly on some coins heads are slightly more likely).

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Is it actually legal not to grab any stones in nigiri?

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I don’t think there are clear written rules about nigiri. But as it is a Japanese custom, I suppose there is a tradional etiquette to not attempt to grab a specific number of stones. So anything less than about 7 may raise some eyebrows.

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Long time ago, I watched Nick Sibicky vs Andrew Jackson video, and there Nick said that Andrew has an odd-sized hand. I wanna say it’s this video https://youtu.be/Ugfc_0zIOhs?t=165 but they don’t say it as I remember it. So me remembering it and something else reminding me of nigiri prompted the question.

On the topic of pros grabbing stones and hand shape.

Summary

In https://youtu.be/uSqg_12K_Rg?t=476 Fujisawa Rina grabs 25 stones, and Ueno Asami hits 1. In https://youtu.be/i36rIryK4Pk?t=358 (noise warning) Fujisawa Rina grabs 25 stones (it’s hard to see but you can count hand movement or zoom in), and Ueno Asami hits 1. Coincidence? I think not. These are literally the first videos I stumbled upon.


image

And since we’re doing this, at this point, let’s go, Fujisawa Rina doing nigiri.

21 here:

23 here:

21 here:

28 here, crap:

21 here:

25 here:

25 here:

Unclear even here:

Unclear odd here:

16 here:

13 here:

Believe it or not, unclear odd here:

22 here:

24 here, although I’m already tired:

In conclusion:
Odd: 13, 21, 21, 21, 23, 25, 25, 25, 25, unclear, unclear
Even: 16, 22, 24, 28, unclear

11:5 in favor of odd here

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Is it actually possible to grab no stones?

Also

What is zero?
  • Even
  • Odd
  • Both
  • Neither

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I could add some to the descriptions like:
Even because it’s between two odd numbers
Odd because its constituents cannot be paired
Both because both the above are true
Neither because zero duh

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The simple mathematical answer is 0 is even and not odd. Here are the relevant definitions:

For integers q, n we say that q divides n (usually in short written as q | n) if there exists an integer m such that n = q * m.

We call an integer n even if 2 divides n.

We call an integer odd if it is not even.

As a consequence, 0 is even and not odd, as 0 = 2*0 and hence 2 divides 0. In fact every integer divides 0.

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During the smog in 1977 in Paris, car use was restricted so that people with licence plates ending in odd or even numbers drove on alternate days.

“The police did not know whether to stop the zero-numbered licence plates and so they just let them pass because they didn’t know whether it was odd or even,”

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You people are crazy

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Does zero divide zero?

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That’s why we like to play correspondence games…

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