Control room agents: an information-theoretic approach
John Andrew van der Poll, Willem Adrian Labuschagne, Petra Laura Van Der Westhuizen · 2007
In this thesis, a particular class of agent is singled out for examination. In order to provide a guiding metaphor, we speak of 'control room agents'. Our focus is on rational decision-making by such agents, where the circumstances obtaining are such that rationality is bounded. Control room agents, whether human or non-human, need to reason and act in a changing environment with only limited information available to them. Determining the current state of the environment is a central concern for control room agents if they are to reason and act sensibly. A control room agent cannot plan its actions without having an internal representation (epistemic state) of its environment, and cannot make rational decisions unless this representation, to some level of accuracy, reflects the state of its environment. The focus of this thesis is on three aspects regarding the epistemic functioning of a control room agent: (1) How should the epistemic state of a control room agent be represented in order to facilitate logical analysis? (2) How should a control room agent change its epistemic state upon receiving new information? (3) How should a control room agent combine available information from different sources? In describing the class of control room agents as first-order intentional systems having both informational and motivational attitudes, an agent-oriented view is adopted. The central construct used in the information-theoretic approach, which is qualitative in nature, is the concept of a templated ordering. Representing the epistemic state of a control room agent by a (special form of) templated ordering signals a departure from the many approaches in which only the beliefs of an agent are represented. Templated orderings allow for the representation of both knowledge and belief. A control room agent changes its epistemic state according to a proposed epistemic change algorithm, which allows the agent to select between two well-established forms of belief change operations, namely, belief revision and belief update. The combination of (possibly conflicting) information from different sources has received a lot of attention in recent years. Using templated orderings for the semantic representation of information, a new family of purely qualitative merging operations is developed. Keywords. control room agents, semantic information theory, nonmonotonic logic, templated orderings, epistemic logic, epistemic entrenchment, epistemic states, AGM postulates, iterated, revision, templated revision, templated update, social choice theory, information fusion, content-based merging.