Adversarial Search
(written 2023)
Two-player, Zero Sum games
- State-machine
- to-move: state \(\to\) player
- actions: state \(\to\) {action}
- result: state \(\times\) action \(\to\) state
- utility: state \(\times\) player \(\to\mathbb{R}\)
- Minimax algorithm:
- maximises utility for the player currently to move
- Tree Search: optimise utility bottom-up
- min nodes and max nodes
- exhaustive research
- Caveats and variations
- Branching factor
- multi-player games - alliances and trust
- co-operative games
- \(\alpha\beta\) pruning
- heuristic searches
- Type A and Type B:
- move generation
- move evaluation
- Monte Carlo Tree Search
- Monte Carlo \(\sim\) Stochastic Simulation
- Balance Exploitation and Exploration
- More Caveats
- Stochastic Games - Chance Nodes
- Partially Observable Games
- the percept sequence is no longer the opponent’s move.
- Limitations - Section 6.7
- Intractible
- Approximations and Assumptions
- Individual moves - no sight of the bigger picture