Enhancing Believability of Virtual Soccer Players: Application of a BDI-Model with Emotions and Trust - Developing Concepts in Applied Intelligence - page 120

Below, the LEADSTO model for decision making with emotions and trust is
introduced (at a conceptual level) in three steps. In Section 2.1, the basic Belief-
Desire-Intention (BDI) model is briefly introduced. Next, in Section 2.2 and 2.3, this
model is extended with mechanisms to represent the dynamics of emotions and trust,
respectively. For the complete LEADSTO specification, see the M.Sc. Thesis in [6].

2.1 BDI-Model

The BDI-model is a standard paradigm within the Agent Technology domain, which
describes how agents decide to perform actions based on their beliefs, desires and
intentions (e.g., [13]). This model forms the foundation of the model presented in this
paper. See the middle part of the global overview in Figure 1. Here the box indicates
the borders of the agent, the ovals denote components of the agent model representing
different mental states, and the arrows indicate influences between mental states.

emotions

observations beliefs desires intentions actions

trust

Fig. 1. Global overview of the BDI-model with Emotions and Trust.

For instance, an action A is executed when the agent has the intention to perform
this action and it has the belief that certain circumstances in the world are fulfilled
such that there is an opportunity to perform the action. Beliefs are created on the basis
of observations. Moreover, the intention to do a specific type of action is created if
there is some desire to reach state S , and the agent believes that performing this action
will fulfill this desire. Such relations within the general BDI-model can be specified
in formal LEADSTO format as follows (where the timing parameters e, f, g, h, as well
as a parameter Ag indicating which agent has the mental states, have been omitted for
simplicity):

∀ S:STATE ∀ A:ACTION

→

desire(S) ∧ belief(satisfies(A, S)) intention(A)

∀ A:ACTION
intention(A) ∧ belief(opportunity_for(A)) → performed(A)

Note that the beliefs used here depend on observations (see Figure 1), or on common
knowledge. In the remainder of this paper, desires and intentions are parameterized
with a real number I (between 0 and 1) to represent the strength of the mental state.