Tactics 101

These internal shapes reliably produce two eyes. Learn to recognize them and you'll instantly assess whether a group is safe:

• Straight four: Four points in a line — the opponent cannot prevent two eyes
• Bent four in open board: Four points in an L-shape — usually produces two eyes reliably
• Bulky five: A 2×2 square plus one additional point — guaranteed life, cannot be killed
• Rabbity six: A distinctive larger shape — alive with comfortable room to spare

And the shapes that die when the opponent finds the vital point:

• Three in a row: The opponent plays the middle point and the group cannot form two eyes
• Square four (2×2): One of Go's most famous dead shapes — the opponent plays inside and the group dies in ko or unconditionally
• Bent four in corner: A famous special case — what looks like it should live actually dies because of the unique geometry of the corner boundary

When attacking a group that is trying to make two eyes, often the goal is to play the "vital point" (nakade in Japanese) — the single interior move that prevents the group from splitting its internal space into two real eyes. Playing that point forces the group into a single large eye that can be captured.

Each internal shape has a specific vital point. Playing that point kills the group. Knowing these vital points by shape is one of the hallmarks of strong tactical play.

Not all living groups have two eyes. "Seki" (mutual life) occurs when two opposing groups share liberties in a configuration where neither player can safely attack the other without killing themselves first.

In a seki position, neither group's stones are captured, but neither player controls the shared space as territory — the points between them are neutral. Seki positions arise most often in corner fights and require careful reading to recognize. A group in seki is alive, but it's worth knowing its status precisely, because misreading seki can lead to costly mistakes.

Ko is a special position where a single stone has just been captured and the opponent would like to immediately recapture — but doing so would repeat the previous board position, which is forbidden by the ko rule.

Instead, the player who wants to recapture the ko must first play a "ko threat" — a meaningful move elsewhere on the board big enough to demand a response. Once their opponent answers the threat, they can then retake the ko.

Studying life and death problems — called "tsumego" in Japanese, or "gisaeng" in Korean — is considered one of the most effective ways to improve at Go. Regular tsumego practice trains you to:

• Read accurately without touching the stones — seeing sequences entirely in your mind
• Recognize vital points for common shapes instantly
• Calculate status quickly — determining whether a group lives, dies, or is in ko with best play from both sides
• Build pattern recognition that carries into every part of your game

Types of tsumego:

• Kill problems: Find the move that kills the opponent's group
• Live problems: Find the move that makes your own group alive
• Status problems: Determine whether the group is alive, dead, or in ko — no hint given
• Ko problems: Find the sequence that creates or resolves a ko

Even 10-15 minutes of tsumego practice daily builds pattern recognition that improves your reading speed and tactical accuracy across all phases of the game.