Go and Tsumego Glossary: Life and Death, Seki, Ko, Atari, and More

Go and tsumego commentary is full of distinctive terms like life and death, seki, ko, and the ladder. Once you know what they mean, problems and explanations become far easier to follow, so here is a glossary of the words that come up most often. Browse to whatever term you need; each topic is explored in depth in the related columns at the bottom of the page.

Tsumego (life-and-death problem)

A go puzzle in which you read out a forced sequence to decide whether a group lives or dies — "can I capture the target stones, or keep mine from being captured?" TsumeDojo's tsumego currently center on capturing-type problems ("capture the target stones"), all verified by exhaustive search; life and death by eye shape — eyes, seki, ko — is on the future roadmap.

Life and death (shikatsu)

Whether a connected group of stones is alive or dead. With two eyes it can never be captured (alive); if it cannot make eyes it is eventually captured (dead). This is the central theme of tsumego.

Liberty (dame / kokyuten)

An empty point directly adjacent to a stone — the point through which it "breathes" (kokyuten, breathing point). When all of a group's liberties are filled by the opponent, the group is captured. Counting liberties accurately is the basis of tsumego and capturing races.

Atari

The state where a stone or group has only one liberty left. Because filling that last liberty captures it next move, atari is the decision point: connect, run, or capture the opponent first.

Capture (toru / nuku)

Filling all of an opponent group's liberties and removing it from the board. Captured stones are called prisoners (agehama) and, under Japanese rules, reduce the opponent's territory at the end. Capturing-type tsumego trains exactly this "read out the capture" skill.

Eye (me)

An empty point completely surrounded by one player's connected stones. In particular, when a group has two eyes the opponent cannot play in either eye — a stone there would have no liberties and be captured at once (an illegal self-capture point) — so the eyes cannot be filled and the group is safe. Whether you can make eyes decides life and death.

Two eyes (nigan)

Two separate, genuine eyes. The opponent cannot fill both in a single move, so a group with two eyes can never be captured (unconditional life) — the ultimate goal of life and death.

False eye (kakeme)

A point that looks like an eye but does not work as one, because the surrounding stones are not properly connected. A group with only false eyes cannot make two real eyes and cannot live. Telling a real eye from a false eye is a key life-and-death skill.

Seki (mutual life)

A standoff in which, if either side tries to capture, it gets captured first — so neither can play, and both groups live together. It is a special form of life without two eyes; at the end the stones count as alive (though the shared empty points in a seki are not territory).

Ko

A shape where each side could capture a single stone back and forth, repeating the same position forever. To prevent this, the ko rule forbids immediate recapture: the player who was just captured must play elsewhere (a ko threat) before taking back.

Ladder (shicho)

A technique that captures by giving continuous atari, driving the stones in a zig-zag toward the edge until they are caught. If a friendly enemy stone (a ladder breaker) sits in the path, the chase fails.

Net (geta)

A technique that captures without giving direct atari, instead sealing off the escape routes as if casting a net. Unlike a ladder, it works no matter how the opponent responds.

Snapback (uttegaeshi)

Deliberately letting the opponent capture your stone, then immediately recapturing the whole group by exploiting the shortage of liberties that capture creates. A "give one to take many" reversal.

Connect-and-die (oiotoshi)

Driving the opponent into a shape where, because of a shortage of liberties, connecting the threatened stones still loses them all. Even answering the atari does not save them.

Nakade (eye-killing shape)

Playing on the vital point inside the opponent's eye space so the group cannot make two eyes, and is killed (the term also refers to the resulting dead shape). The vital point is fixed by the size and shape of the space — three-space, four-space nakade, and so on.

Shortage of liberties (damezumari)

When your own group runs short of liberties so that you cannot connect or escape and end up captured. In tsumego, forcing the opponent into damezumari is often the decisive move.

Vital point (kyusho)

The single most important point that decides the life, death, or fight in a shape. "The opponent's vital point is your vital point" — the same point is often key both to living and to killing.

Tesuji and territory (tesuji / ji)

Tesuji is a skillful, shape-specific move that gets the most out of a local position (ladders, nets, snapbacks, and the like); tsumego is a treasure trove of tesuji. Territory (ji) is the empty points surrounded by your own stones — at the end, the side with more territory plus prisoners (captured stones) wins.