traditional game playing 2 player adversarial (win => lose) based on search but... huge game...
TRANSCRIPT
traditional game playing
• 2 player
• adversarial (win => lose)
• based on search
• but... huge game trees can't be fully explored
traditional game playing• 2 player• adversarial (win => lose)• fixed rules – no general world kn• based on search but...
huge game trees – can't be fully explored
why study them in AI?• core part of tools & techniques• adversary modelling is important
economics, contingency planning & other areas
trad. game playing
• basics• minimax search routine
• depth 1st to fixed depth• different approaches to copy, cache, states
• static evaluation fn• assesses merit of game states for players• simple +/- numeric value
• alpha-beta pruning• std approach for reducing game trees
alpha – beta … continued
• best & worst cases
• improving alpha-betasimple ordering fns
eg: captures => threats => moves
other strategies (growth, etc)
• eval all nodes & extend treeheuristic growth
quiescence
plausibility effort
• use different eval fns at different stagesstrategy, performance, etc
• library moves (open game / end game)state representations
database lookup
other strategies (pruning)
• eval all nodes & prune treeheuristic pruning
limiting breadth
futility cut-off
• caching stateswhen/why to cache
cache persistence=> library moves?
minimum needs
1. a state representation
2. a static evaluation fn
3. a legal move generator
4. minimax
5. alpha-beta pruning?
uncertainty
1. chance – dice games, etc
2. incomplete kn – cards, etc