Multipurpose Adversary Planning in the Game of Go

Ph.D thesis by Shui Hu

Presenter: Ling Zhao

Date: November 18, 2002

OutlineMotivationsOverviewBasic structures and conceptsCombining goalsA concrete exampleConclusions

MotivationsGo is a strategy gameComputer Go programs still have

difficulties to convey human’s knowledge

Multi-purpose moves are quite common in human-played Go games

Traditional multi-valued move is too passive!

OverviewHeuristic adversary planningStatic analysis and dynamic look aheadLook for combined goals and the steps

leading to themStrength: actively search for combined

goalsWeakness: only a prototype, hard to

implement in a real system

Basic structures Hierarchy of objects: group, chain,

string, stone Generate goals:1. high level goals are generated by static analysis

(using knowledge base)

2. low level goals are generated by looking ahead

Goal structure (see example next next page)

Knowledge base

Goal Tree

Goal relationsGoal and subgoalsMaster and servant goal

AchievabilityBlack to move, and the goal is to kill white group

Achievable:

Near-achievable:

Decide the achievabilityStart from leaf goalsGenerate goal/counter goal pairsUse look ahead searchPropagate results upwardNote this method can also decide the

achievability of combined goals

CP2 search procedure

g11 : (g11, c11) (g11, c12) (g11,c21) … (g11, c33)g12 : (g12, c11) (g12, c12) (g12,c21) … (g12, c33)

g33 : (g33, c12) (g33, c12) (g33,c21) … (g33, c33)

Interaction of leaf goals If the intersection of moves to realize two near-

achievable goals is not empty, we find some multipurpose moves!

Combine two goals and use the look ahead to decide if the multipurpose moves can make one of the near-achievable moves achievable.

If yes, your multipurpose planning works. The example explains the situation similar to

double threats, and there are more situations.

Example

Goal Tree

Goal Tree

ConclusionsA multipurpose planning framework was

brought outPrototype, can only work on very few

finely designed examplePlanning is weak, and almost the same

as search.