Exchange

    Keywords: Go term

An exchange has two meanings in Go - either the comparison of the same number of Black and White plays (usually one) or the sudden redistribution of territory. The former is defined here; for definition/examples of the latter, see furikawari.


Exchanges can be good or bad. Bad exchanges are usually aji keshi, as they use up the aji with little benefit (or none at all). Sometimes it is hard to know whether an exchange is good timing or whether it unnecessarily removes ko threats. Easy to spot exchanges where the first player has the prerogative to make the exchange are called kikashi.

[Diagram]
Exchange  

The prime example of an ambiguous exchange - whether W1/B2 is good or not depends on the rest of the board. White's goal is to make W1/B2 a good exchange (do more work with W1 than Black can do with B2).

[Diagram]
Good exchange  

This W1/B2 is a good exchange. White will have little chance to cut at B2, and W1 will help White's next play(s) to reduce/invade the Black formation on the top. It also breaks ladders that may result in contact fights with black+circle.

[Diagram]
Good exchange  

Here B1/W2 is a good (albeit necessary) exchange for life after B3. Without B1 the Black group is dead (see J group).

[Diagram]
Good exchange  

The peep B1/W2 is a good exchange, helping to make the outside stones heavy before connecting under at B3. Black will make better use of the wall White gave by invading the corner.

[Diagram]
Bad exchange  

Here B1/W2 is definitely bad. Black loses a liberty and activates a White cut at a, while Black gains nothing and loses a ko threat.

[Diagram]
Bad exchange  

B1/W2 is a raw peep. Black makes very little use of the black+circle stones. Cutting at W2 would have definitely been better.

[Diagram]
Bad exchange  

B1/W2 is also bad, removing a liberty from Black's stones and giving up the opportunity to play directly at W2 later, should Black have the good fortune to play at a.


Bill: I do not think that the meaning described here is specific to go. Rather, it is an ordinary meaning of the English word. Once again, we have a word with more than one meaning. Why privilege either one?

kb: The Chinese term for exchange (交换) means both and is an ordinary meaning in that language as well. The old page pointed directly to furikawari, which is not the only meaning of the word "exchange" as used in Go. I have no idea whether furikawari is "privileged" in Japanese as per your implied definition. :(

Bill: It is a good idea to add the other meaning of exchange. It was missing from the original page. But why devote this page to only one meaning of the word? Why not give both meanings, and, if necessary, link to other pages that say more? I doubt if furikawari needs its own page. However, your discussion of good and bad exchanges deserves its own page, don't you think? Something like Exchanges -- good and bad? You really are writing an essay, not just explaining a term. :)


Exchange last edited by tapir on January 13, 2012 - 22:31
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