Contemporary Go Terms: Airport and Toothpaste

Published 25 Jul 2021 by antti (last edited 25 Jul 2021)
tags: tldr, terms

Learning new go terms has a bigger impact on one’s improvement than many players give credit for. While the terms themselves are mere placeholders, they refer to shapes and strategical concepts in the game that are usually worth learning. For instance, imagine not having a term for ‘hane’ or ‘one-space jump’; besides the terms allowing for smooth communication between players, knowing them as concepts also helps us construct higher-level ideas such as ‘you should hane at the head of two stones’ or ‘a one-space jump is never bad’. Terms are the main ingredient in your go skills toolbox.

In this post I would like to introduce two contemporary go terms that are (as far as I know) of Finnish origin, not yet widely known in go circles, yet (I think) valuable to learn: the ‘airport’ and the ‘toothpaste’.

The airport

Every framework wants to be an airport. An airport is a large, box-shaped framework that has turned into territory, with few or no stones inside. The black centre framework in Dia. 1, taken from a teaching game of mine, is a prime example.

Dia. 1
A black airport

For the origin of the term, imagine you are looking at a satellite photo of a tightly-built metropolis, where the airport takes up a large open space – like below, for instance.

Dia. 2
Totally lifelike

An airport is optimal when a player has been able to finish it without the opponent having made use of its potential weaknesses. For example, the original framework may have had cutting points that may have been problematic if the opponent attacked them – however, the opponent did not touch the weaknesses and let the airport-builder fix them while simultaneously securing territory in the airport.

Dia. 3
White’s main aims

Earlier in the game, White slightly reduced the black framework from the outside with 1–2, and then invaded with 3 which eventually led to a white life on the upper side. However, White’s main targets should have been the black cutting points marked ×. Checking Dia. 2, we notice that White has used none of these cuts, and this is a prime reason to why Black was able to surround so much territory in the centre – he was able to omit three defending moves!

Dia. 4
A sample cut

For example, cutting with 1 in Dia. 4 would put much more pressure on Black. Note that Black cannot simply capture White in a ladder with 2–6, as then White will inevitably get a severe ladder-breaker such as 7, aiming for ‘a’ and ‘b’ simultaneously. This way, White will likely get to form a larger living group in the centre, reducing more of Black’s territorial potential than in the game.

Dia. 5
Cut cut cut

If Black instead plays the hanging connection of 4, White may cut again at 5; now Black is clearly too busy helping his stones that he cannot focus on turning the framework into territory. In the close future, White may also aim to get a ladder breaker for the last cutting point at ×.

While it looks like White is ‘attacking’ Black, here, in reality his goal is just to find a good way to start forming life in the centre. Challenging the black stones forming the framework is a good way to do this, since if White can get Black on the defensive, White will inevitably get useful forcing moves that he can use in forming eyes.

Dia. 6
Two airports

This is a game by two students in the ngd online league. White has a kind of an airport in the centre in this game, but, in fact, so does Black on the lower side. This was finally a very close game all the way into late endgame.

Dia. 7
White’s chance

Dia. 7 shows the situation in the middle game. Here, White has been able to form territory around the cutting points at ×, therefore making his stone efficiency good in this part of the board. Black has just connected at 73, and, if White were now to play at ‘a’, he could prevent the lower-side black airport from forming, which would probably put him in the lead. In the game White missed this opportunity, and Black finally got the large lower-side territory we see in Dia. 6.

An airport, then, is a framework turned into territory without the opponent having made use of its weaknesses. In other words, the builder of an airport has managed to form territory at their framework’s cutting points.

The toothpaste

Toothpaste refers to a shape where a player’s stones tightly envelop the opponent’s so that there are basically no shared liberties. This kind of a shape tends to favour the player who is getting enveloped, as the two players in go always play an equal number of moves: the player with the outside stones inevitably ends up with severe cutting points.

Dia. 8
Black’s jōseki mistake
Dia. 9
White is toothpasted

A quintessential toothpaste shape results from the jōseki with 1–8 in Dia. 8, where Black mistakenly plays the hane of 9. (Instead of 9, black ‘a’ and white 9 would conclude the jōseki.)

With 10 and on in Dia. 9, White toothpastes himself: up to 17, White’s stones are tightly enveloped by Black, and White can look forward to the cutting moves at ‘b’ and ‘c’. White ‘b’ already captures at least one black stone.

Dia. 9 also depicts the term rather well: imagine the black stones form a hand that is tightly squeezing a toothpaste tube, with white toothpaste oozing out from both ends of the tube. Afterwards, Black needs to spend a lot of effort cleaning up the mess.

Strategically, then, because a toothpaste shape is bad for the one whose stones are on the outside, you do not want to toothpaste the opponent; you instead want to force the opponent to toothpaste you.

Dia. 10
In Reversi

Incidentally, if you are familiar with Reversi (or Othello), this dynamic is not altogether different with the one in Reversi where you want to have your pieces in the middle of your opponent’s. The reason to this is different, however, since in Reversi the utility comes from having a lot of moves available, while in go it is the resulting cutting points that bring the surrounded player the value.

Although toothpasty shapes come up fairly often in professional games, I suspect Hon’inbō Shūsai was the first real toothpaste master, as he constantly made use of it in his fighting games. See below for a famous example, a 1926 game against Karigane Jun’ichi 7p (the game is also visible in an sgf reader at the end of this article). Sharp-eyed readers may recognise this as the Sai v. Kaga game in Hikaru no Go.

Figure 1 (1–20)
Figure 2 (21–40)

Seeing Black’s attack of 39, White starts a fight on the lower side.

Figure 3 (41–60)

White 48, etc. start a really complicated mêlée on the lower side, denying Black’s group of two eyes.

Figure 4 (61–80)

After 70, Black still cannot form two eyes on the lower side, so he instead has to try to get something out of White’s outer cutting points. However, White has read out that he cannot be easily sealed in, and that the resulting shape is instead toothpaste.

84 at a
Figure 5 (81–100)

Up to 100, the mess spreads all the way into Black’s left-side territory.

13: kō, 14 at a; 16, 19: kō
Figure 6 (101–120)

A high-stakes kō fight seems like a fitting end to this fight.

24 at a, 35 at b
Figure 7 (121–140)

Up to 39, White basically secures the capture of the lower-side stones, and next the game turns to the aftermath of the toothpasting with Black’s cutting points on the outside. Because Black’s centre group is still facing considerable pressure, the game is going well for White regardless of his ugly-looking clump of stones.

As this game by Shūsai and Karigane also suggests, successful toothpasting requires solid reading skills for proper implementation. For maximal effect, you want to have your stones squeezed through the narrowest possible gap, as White did with 90–100 in Figure 5. However, White had to have that part read out much earlier, at move 70 at the latest, as without precise reading the white stones might just have gotten captured outright.

As we can see from the outcome in Figure 7, when applied properly, a proper toothpaste can be really efficient.

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