RobertJasiek/Efficiency

fewest number of plays  

Black achieves the task with 6 plays. This is efficient.

greater number of plays  

Black achieves the task with 7 plays. This is inefficient, because Black spends one play too many, which he would better play elsewhere.

Example 2 for same number of black plays: Suppose the task is to live while making the most territory. Each diagram needs 6 black stones played.

efficient  

Black has played 6 stones to get life with 4 points. This is efficient.

inefficient  

Black has played 6 stones to get life with at most 3 points. This is inefficient.

Territory efficiency

The territory efficiency of a player's territory region is his current territory there divided by his number of stones played to achieve it. ^[2]

Example 3

territory efficiency 0.67  

Black has 4 points made by 6 stones played. His territory efficiency is 4/6 ~= 0.67. This is inefficient.

Example 4

territory efficiency 1  

Black has 6 points made by 6 stones played. His territory efficiency is 6/6 = 1. This is better than in Example 3. In relation, Black has made territory more efficiently.

Example 5

territory efficiency 1.83  

Black has 11 points made by 6 stones played. His territory efficiency is 11/6 ~= 1.83. This is more efficient than in Examples 3 and 4.

Movement speed

Efficiency is the optimal compromise between safety and speed of local movement. ^[3]

This more specialised description of efficiency has, however, its merits for related application.

Example 6