Capturing Race (Semeai) in Go: When Two Groups Fight for Air
⏱ Read ~4 min · Updated July 2026 · Part of: Learn Go
A capturing race (對殺, semeai) is the tensest moment in Go: two enemy groups, neither with eyes, share a border and fight for the same outside liberties. One will run out of air first and be captured. Counting right decides who lives.
| English | 中文 | Plain meaning |
|---|---|---|
| capturing race | 對殺 | two eyeless groups fight for air |
| semeai | 對殺（日） | same thing, Japanese term |
| liberty | 氣 | empty neighbor — breath |
| eye | 眼 | surrounded empty point (would end the race) |
1. What a capturing race is
Two groups sit next to each other. Neither can make two eyes, so neither is permanently safe. The only question: who has more liberties, and who can reduce the other to zero first?
🥊 Analogy: two wrestlers in a small room with one air vent. They're not trying to make their own window — they're trying to plug the other's. Whoever suffocates first loses.
2. The basic count
Count each group's liberties (empty points touching it, not shared with the enemy). The group with more liberties generally wins — it can afford to trade one-for-one and still have air left.
🎯 Simple rule: if my group has more liberties than yours, and neither of us makes an eye, I win the race.
3. Shared liberties and eyes complicate it
Real races have two twists:
- Shared liberties — empty points touching both groups. These usually help whoever is already ahead, and the math gets subtle.
- Making an eye mid-race — if one side can form a single eye during the fight, it gains a huge advantage (an eye can't be filled until the group has no other liberties).
That's why strong players read races several moves deep, watching for the moment to make an eye or deny one.
4. Capturing races vs seki
Sometimes a race ends in seki (雙活) — neither side can capture the other, so both live in a frozen draw. This happens when shared liberties mean whoever moves first gets captured. Recognizing "this race is actually seki" saves you from wasting moves.
5. On a 4×4 board
Small boards produce short, sharp races where the count is easy to do out loud. Many 4×4 puzzles are secretly a one-move race: find the move that puts the enemy group in atari while keeping yours alive. Count the liberties, then act.
Try it
Counting a race under pressure is a skill — practice it on short puzzles with instant feedback.
👉 Play brainGO — win your first race
Related guides
- Learn Go: the visual beginner's guide
- What is a "liberty" in Go? — what you count in a race
- Seki (mutual life) — when a race is a draw