4 – Internal Structures

Internal Structures : Emotional State, Knowledge Base and Autobiographic Memory

Just as the Emotional State leads with what emotional state the agent starts with these components deal with the Memory of the agent at the start of the scenario.

• Knowledge Base: 
  • Stores the agent’s beliefs about the environment
    • Properties of agents and objects
    • Relationships
• Autobiographic Memory:
  • Stores the agent’s recollection of past events and emotions associated with it

In FAtiMA beliefs and events are described by “Well-Formed-Names” (WFN):

• Symbols:
  • Represent constant entities (actions, objects, name of properties, name of relations)
  • Ex: “Sam”, “A1”, “Table”
• Variables:
  • Represent an entity or value that is not specified yet
  • Can be replaced by symbols
  • Ex: “[x]”, “[target]”
• Composed Names
  • Represent properties or relations
  • Ex: “Likes(Emys,Chocolate)”, “Has(Sam, [x])”

Additionally, as we mentioned, we can store past events in the Autobiographic Memory.

Event names represented by a composed name: 

• Event(Action-Start, Player, Smile, John)
• Event(Action-End, Player, Greet(Casual), John)
• Event(Property-Change, World, Weather(Now), Raining)

Above are the 3 types of events present in FAtiMA. Action-Start and Action-End define when a particular action starts and when it finishes. The Property Change events are used to update variables in the beliefs of the agent. They are defined using the following template:

• Action-Start:  Event(Action-Start, Subject, Action, Target)
• Action-End: Event(Action-End, Subject, Action, Target)
• Property-Change: Event(Property-Change, Subject, Property Name, New Value)

The Subject field represents which agent started or finished that event.

Here is what I wrote on Charlie’s beliefs, the last one relates to the state of the conversation Charlie will have with the Player.