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BDI

The philosopher Michael Bratman described humans’ practical reasoning via the “beliefs, desires, intentions” framework, as a way to explain future-directed decisionmaking. Successively, the framework was formalised by means of modal logics, and then turned into an abstract semantic for computational agents: AgentSpeak(L).

Computational agents are autonomous entities situated into an environment they can perceive and affect; they interact either directly or through the environment by means of stigmergy. The classical implementation of BDI agents, based on the Procedural Reasoning System (PRS), is characterized by four main abstractions, namely:

  • Beliefs: a set of facts and rules representing an agent’s epistemic memory, possibly describing its knowledge about the world, itself, and other agents;
  • Desires: a set of goals, representing (possibly partial) descriptions of desirable states of the world the agent is willing to achieve, test, or maintain;
  • Intentions: a set of tasks the agent is currently committed to, in order to satisfy some of its desires;
  • Plans: a set of recipes representing the agent’s procedural memory, hence encoding the know-how about achieving a given intention under certain conditions.

Any instance of the aforementioned abstractions in a BDI agent may vary during its lifetime. For instance, novel beliefs appear in the agents’ minds whenever they receive novel perceptions from their sensors, while stale beliefs simultaneously disappear.

While carrying on an intention, agents may select one or more plans among those supporting the corresponding intention’s accomplishment. Plans may involve the execution of one or more actions – possibly affecting the environment via actuators – or the accomplishment of further sub-goals, which may, in turn, require the execution of further plans as part of the same intention. Finally, agents could even learn entirely new plans, either through reasoning or through information sharing with other agents.

Concerning intentions

Even though Intentions are first-citizen elements in BDI concepts, those are not explicitly represented in agents programs. The purpose of "hiding" this structure is to exacerbate the agent's commitment on acting for reaching its goals.

Source reference: Blending BDI Agents with Object-Oriented and Functional Programming with JaKtA