Joint Graphs¶
Joint graphs are the shared representation that connects world modelling, opponent modelling, and shielding.
A joint graph represents public environment states and joint actions across all agents.
Main Artifacts¶
The active pipeline uses two central graph artifacts:
legal_joint_graph.pkl contains exact legal topology only.
env_transition_graph.pkl contains the same topology plus learned environment transition probabilities and rewards.
Opponent probabilities are not saved as a separate base artifact. They are applied later when inducing the focal-agent MDP for a given opponent model.
Why Joint Actions¶
In multi-agent environments, the next state usually depends on all agents' actions.
A joint action records the combined action choice. The focal agent controls its own component, while the opponent model supplies probabilities for the other agents' components.
Focal MDP Induction¶
Shielding needs a single-agent view for the focal agent.
The graph induction step combines:
- environment transition probabilities,
- opponent action probabilities,
- the focal action being evaluated.
The result is a focal MDP for a specific opponent-model level or mixture of levels. Sound value iteration runs on this induced structure.