Agent Theories, Architectures, and Languages: A Survey <s> Rosenschein & Kaelbling -situated automata <s> Researchers using epistemic logic as a formal framework for studying knowledge properties of AI systems often interpret the knowledge formula K(x, φ) to mean that machine x encodes φ in its state as a syntactic formula or can derive it inferentially. By defining K(x, φ), instead, in terms of the correlation between the state of the machine and that of its environment, the formal properties of modal system S5 can be satisfied without having to store representations of formulas as data structures. In this paper, we apply the correlational definition of knowledge to machines with composite structure. In particular, we describe how epistemic properties of synchronous digital machines can be analyzed, starting at the level of gates and delays, by modeling the machine's components as agents in a multi-agent system and reasoning about the flow of information among them. We also introduce Rex, a language for recursively computing machine descriptions, and illustrate how it can be used to construct machines with provable knowledge properties. <s> BIB001 </s> Agent Theories, Architectures, and Languages: A Survey <s> Rosenschein & Kaelbling -situated automata <s> Embedded agents are computer systems that sense and act on their environments, monitoring complex dynamic conditions and affecting the environment in goal-directed ways. This paper briefly reviews the situated automata approach to agent design and explores issues of planning and action in the situated-automata framework. <s> BIB002 </s> Agent Theories, Architectures, and Languages: A Survey <s> Rosenschein & Kaelbling -situated automata <s> Although the concept ofknowledge plays a central role in artificial intelligence, the theoretical foundations of knowledge representation currently rest on a very limited conception of what it means for a machine to know a proposition. In the current view, the machine is regarded as knowing a fact if its state either explicitly encodes the fact as a sentence of an interpreted formal language or if such a sentence can be derived from other encoded sentences according to the rules of an appropriate logical system. We contrast this conception, the interpreted-symbolic-structure approach, with another, the situated-automata approach, which seeks to analyze knowledge in terms of relations between the state of a machine and the state of its environment over time using logic as a metalanguage in which the analysis is carried out. <s> BIB003
Another sophisticated approach is that of Rosenschein and Kaelbling BIB003 BIB001 BIB002 . In their situated automata paradigm, an agent is specified in terms of a logic of knowledge. This specification is then compiled down to a low-level digital machine, which satisfies the intentional specification. The technique depends upon the possibility of giving the worlds in possible worlds semantics a concrete interpretation in terms of the states of an automaton: '[An agent] … x is said to carry the information that p in world state s, written s | = K(x, p) , if for all world states in which x has the same value as it does in s, the proposition p is true.' [76, p36] The authors have developed several software tools to assist in the construction of agents: the Ruler program is used to specify the perception component of an agent; the Gapps program is used to specify the action component. Both of these languages are implemented over a third, LISP-like language, called Rex, which is used to specify simple digital machines. The situated automata paradigm has attracted much interest. However, at the time of writing, the theoretical limitations of the approach are not well understood.