Efficient Selectivity and Backup

Operators in Monte-Carlo Tree Search

Presented by Melvin Zhang

Remi Coulom, Computer and Games 2006

http://rusgo.org/crazystone/

http://www.wired.com/2014/05/the-world-of-computer-go/

SelectionPrinciple: Move that look best should be searched deeper, andbad moves should be searched less

SelectionPrinciple: Move that look best should be searched deeper, andbad moves should be searched less

Crazy Stone: Each move i is selected with probabilityproportional to

exp

(−2.4

µ∗ − µi√2(σ2

∗ + σ2i )

)+ εi

Backup/Update

Update the statistics at internal nodes base on result ofsimulation. Affects subsequent selection.

Backup/Update

Update the statistics at internal nodes base on result ofsimulation. Affects subsequent selection.

Crazy Stone: Uses “Mix” operator, linear combination of meanand robust max

meanaverage of child nodes

maxmax of child nodes

robust maxchild node with the most simulation

http://peepo.com/go.html

https://code.google.com/p/magarena/