Liberty (version 36)

Liberty has two different, but related meanings in English.

The first is an empty point adjacent to a single stone or chain of stones. This is the primary meaning, and the number of liberties in this sense is straightforward to count for any chain of stones.

OTF: Liberties  

As you can see in this diagram,

• a stone which is not on the first line has at most four liberties
• a stone on the first line which is not in the corner has at most three liberties
• a stone in the corner has at most two liberties

OTF: White's liberties  

The group of three white stones has three liberties.

The second sense, important for tactics, is a play required to capture a single stone or chain of stones. This sense may be extended to discussion of groups of several chains, to help answer the question 'how many plays does it take to capture that group?' This is actually a considerably more advanced question, which cannot so simply be answered by inspection.

When a single stone or a chain of stones loses its last liberty, it is captured and is immediately removed from the board. Since suicide is forbidden under the usual rules, this happens when the opponent's play fills the final liberty of a chain that was already in atari.

Sometimes it takes more plays to capture a stone or chain of stones than its number of adjacent empty points. There can be problems of access to the liberties. That's to say: a chain isn't always such that you can put it in atari by the direct method of filling in liberties one by one. Preliminary approach moves may be required.

Example: letter E  

How many liberties does this shape have left? There are 13 liberties (primary sense) marked with circles. But Black will need an approach play at one of a and b to put White into atari successfully without losing two stones. Therefore White's chain has one more (secondary) liberty than meets the eye.

Often therefore an approach move is counted in as a 'liberty' in the second sense. The other typical reason is that filling liberties inside, as shown for example on the attrition method page, requires repeated plays under the stones, that is, on points that become vacant when the opponent captures.

Further secondary liberties examples.

Comments:

• Liberty in Chinese is 气 ("Qi" in pinyin), which means "breath". The thought is that stones need breathingspace and that once the last breathing space is removed, the stones die.
• This is the same "Qi" as the one considered to be beneficial in terms of Feng Shui.
  

Bill: Is breath also ambiguous? Or does it only refer to adjacent points? :-)

unkx80: This 气, or breath as you call it, can be as ambiguous as liberty.

! Further reading

Give me liberties: a path to all subjects where liberties count.

Authors

• MortenPahle (10k)
• DieterVerhofstadt (WME on 30/10/2002)
• Bill Spight
• Zhang Hu
• Charles Matthews